gf gause paramecium experiment

Competition between Paramecium species

The fourth example comes from the classic work of the great Russian ecologist G. F. Gause, who studied competition in laboratory experiments using three species of the protozoan Paramecium (Gause, 1934, 1935). All three species grew well alone, reaching stable carrying capacities in tubes of liquid medium. There, Paramecium consumed bacteria or yeast cells, which themselves lived on regularly replenished oatmeal (Figure 8.3a).

When Gause grew P. aurelia and P. caudatum together, P. caudatum always declined to the point of extinction, leaving P. aurelia as the victor (Figure 8.3b). P. caudatum would not normally have starved to death as quickly as it did, but Gause's experimental procedure involved the daily removal of 10% of the culture and animals. Thus, P. aurelia was successful in competition because near the point where its population size leveled off, it was still increasing by 10% per day (and able to counteract the enforced mortality), whilst P. caudatum was only increasing by 1.5% per day (Williamson, 1972).

By contrast, when P. caudatum and P. bursaria were grown together, neither species suffered a decline to the point of extinction - they coexisted. But, their stable densities were much lower than when grown alone (Figure 8.3c), indicating that they were in competition with one another (i.e. they 'suffered'). A closer

... between Paramecium species,...

Figure 8.3 Competition in Paramecium. (a) P. aurelia, P. caudatum and P. bursaria all establish populations when grown alone in culture medium. (b) When grown together, P. aurelia drives P. caudatum towards extinction. (c) When grown together, P. caudatum and P. bursaria coexist, although at lower densities than when alone. (After Clapham, 1973; from Gause, 1934.)

look, however, revealed that although they lived together in the same tubes, they were, like Taniguchi and Nakano's fish and Connell's barnacles, spatially separated. P. caudatum tended to live and feed on the bacteria suspended in the medium, whilst P. bursaria was concentrated on the yeast cells at the bottom of the tubes.

Continue reading here: Competition between diatoms

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Recommended Books

• Gause, G.F. (1934). The Struggle for Existence.
• Gause, G.F. (1935). The Principles of Genetics.
• Clapham, A. (1973). Competition between Paramecium Species: Species Richness.
• Williamson, M. (1972). The Evolution of Competition.

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• The Lotka Volterra equations

Readers' Questions

Which of the following best describes how a swimmer moves through the water?

A swimmer moves through the water by applying thrust or force against the water with their arms and legs, propelling themselves forward. This is usually achieved through a combination of arm strokes and leg kicks. The swimmer's body position and technique play a significant role in minimizing drag and maximizing propulsion.

Which factorsmost influence the populations of paramecia when raised separately?

Several factors can most influence the populations of paramecia when raised separately. These factors include: Nutrient availability: The presence of sufficient nutrients in the environment is essential for the growth and reproduction of paramecia. The availability of food sources such as bacteria or organic matter can limit or promote their population size. Temperature: Paramecia are sensitive to temperature variations. Extreme temperatures, either too hot or too cold, can hinder their growth and reproduction. Optimal temperatures range between 20-30 degrees Celsius. pH levels: Paramecia prefer slightly alkaline or neutral pH levels (around 7-8). Drastic changes in pH can negatively impact their populations and may lead to death or reduced reproductive capabilities. Oxygen and carbon dioxide levels: Paramecia require a well-aerated environment to survive. High oxygen levels are necessary for their metabolic activities, while increased carbon dioxide levels can be detrimental to their population growth. Contaminants and toxins: Presence of pollutants, heavy metals, chemicals, or toxins can be harmful to paramecia populations. Exposure to such substances can lead to reduced reproductive rates or even death. Predation and competition: The presence of natural predators or competing species can impact paramecia populations when raised separately. For example, the presence of larger organisms like rotifers or ciliates that prey on paramecia can limit their population growth. It is essential to maintain optimal conditions for each of these factors to ensure healthy and sustainable paramecia populations when raised separately.

Why does p. aurelia beat p. caudatum?

Paramecium aurelia beats Paramecium caudatum due to its ability to move faster and exhibit more agile swimming behavior. This results in better maneuverability and the ability to catch and consume P. caudatum. Additionally, P. aurelia has a larger size, larger mouth, and longer cilia, which allow it to capture and ingest P. caudatum more effectively. It also has a more efficient food processing system, enabling it to extract nutrients more efficiently from the consumed prey. These advantages contribute to P. aurelia's ability to outcompete and beat P. caudatum for resources in their natural environment.

Which of the following statements best explains the relationship shown on the graph?

It seems that the graph was not provided. Please provide the graph or describe its relationship so that I can assist you accordingly.

Which statement best describes the relationship between network effects and innovation?

The statement that best describes the relationship between network effects and innovation is that network effects can drive innovation. Network effects refer to the increased value or utility that a product or service gains as more people use it. This, in turn, incentivizes companies to innovate and create better products or services to attract and retain users. As more users join a network, there are more opportunities for feedback, collaboration, and the emergence of new ideas, leading to continuous innovation. Additionally, network effects can also create barriers to entry for competitors, encouraging companies to invest in innovative solutions to maintain their competitive advantage.

Which of the following best describes an advanced center differential?

An advanced center differential is a component commonly found in all-wheel drive (AWD) systems. It is designed to distribute power between the front and rear axles, allowing for optimal traction and stability in various driving conditions. It is typically more technologically advanced than a traditional center differential, offering features such as torque vectoring, which can actively vary the power distribution between the axles and even individual wheels to enhance handling and performance.

Which of these statements regarding the industry life cycle is correct?

It is difficult to determine which statement regarding the industry life cycle is correct without knowing the specific statements provided. Could you please provide the statements you are referring to?

Which of the following best describes extinction?

Extinction refers to the complete disappearance or dying out of a species or group of organisms. It occurs when a species cannot adapt to changing environmental conditions, faces competition from other species, or experiences a catastrophic event that leads to its demise. Extinction can occur naturally or as a result of human activities such as habitat destruction, pollution, overhunting, or climate change.

Which of the following best illustrates a line flower?

Unfortunately, you have not provided any options for me to choose from. Could you please provide the options so that I can help you?

Which of these best describes how limited resources can lead to differential reproductive success?

The concept of limited resources relates to the fundamental principle of natural selection. Limited resources can lead to differential reproductive success by creating competition among individuals for access to those resources. In an environment with limited resources, individuals that are better adapted to acquire and utilize those resources have a higher chance of surviving and reproducing. The individuals with advantageous traits have a competitive edge over others, allowing them to outcompete and out-survive their peers. Through the process of natural selection, the advantageous traits become more prevalent in subsequent generations as they are passed down to offspring. This leads to a differential reproductive success, as individuals with these advantageous traits have a higher likelihood of producing more offspring that inherit the beneficial traits. For example, in a population of birds where food resources are scarce, those with longer beaks may be better suited to extract food from certain sources. These birds have a higher chance of survival and reproductive success compared to individuals with shorter beaks. Over time, the population may evolve to have longer beaks as the birds with these traits have a higher chance of passing them onto future generations. Overall, limited resources create selective pressures that favor individuals with traits that enhance their ability to acquire and utilize those resources. This results in differential reproductive success, shaping the traits and characteristics of populations over time.

When two species interact within a habitat, competitive exclusion can be observed if?

one of the species outcompetes the other and successfully occupies all available resources. This can lead to the local extinction of the weaker species. Competitive exclusion occurs when two species have similar ecological requirements and compete for the same resources such as food, space, or mates. If one species is more efficient at utilizing these resources or has a competitive advantage, it can outcompete and exclude the other species from the habitat.

Which of these statements regarding the industry life cycle is true?

It would be helpful to include the options you are referring to in order to provide an accurate response.

Which of the following statements are true concerning electromagnetic radiation fields?

To provide a comprehensive answer, I would need to know the specific statements you are referring to. However, I can provide some general information about electromagnetic radiation fields. Electromagnetic radiation fields are produced by electrically charged particles or changing magnetic fields. This is true. Electromagnetic radiation is created by the acceleration or oscillation of charged particles. Electromagnetic radiation fields consist of waves of electric and magnetic fields. This is true. Electromagnetic radiation consists of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of propagation. Electromagnetic radiation fields can travel through a vacuum. This is true. Unlike sound waves, which require a medium for propagation, electromagnetic radiation can travel through a vacuum, such as empty space. Electromagnetic radiation fields can have different frequencies and wavelengths. This is true. Electromagnetic radiation spans a wide range of frequencies and wavelengths, from radio waves with long wavelengths to gamma rays with short wavelengths. Electromagnetic radiation fields can interact with matter. This is true. When electromagnetic radiation encounters matter, it can be absorbed, reflected, transmitted, or scattered depending on the properties of the material and the characteristics of the radiation. Electromagnetic radiation fields can be harmful to living organisms at certain intensities or frequencies. This is true. At high intensities or certain frequencies, electromagnetic radiation can have harmful effects on living organisms, such as causing tissue damage or increasing the risk of cancer. However, at lower intensities and within certain frequency ranges (e.g., visible light), electromagnetic radiation is generally not harmful. Remember that specific statements may have additional conditions or qualifications, so it is important to review the exact statements to determine their accuracy.

Which of the following statements about competition and rivalry is true?

It is impossible to provide a list of statements without knowing the options mentioned. Could you please provide the options or rephrase your question?

When species compete, they are competing to accomplish the goal of?

survival and reproduction.

Which of the following is a true statement concerning model organisms?

A true statement concerning model organisms is that they are commonly used in scientific research to study biological processes and diseases.

Which of the following statements regarding freshwater fish and saltwater fish is/are true?

Without knowing the statements provided, it is impossible to determine which ones are true. Could you please provide the statements?

Which of the following is a common strategy for successful intraspecific competition?

One common strategy for successful intraspecific competition is resource partitioning. Resource partitioning involves the division of limited resources, such as food, space, or mates, among individuals within the same species. This can be achieved through various mechanisms, including spatial segregation, temporal segregation, or morphological differentiation. By utilizing different resources or occupying different niches, individuals can reduce competition and optimize their chances of survival and reproduction.

Which of the following statements best describes protozoa?

Protozoa are single-celled organisms that belong to the kingdom Protista.

Which of the following protists has a mouthlike opening surrounded by cilia used to consume food?

The protist that has a mouthlike opening surrounded by cilia used to consume food is Paramecium.

Why are paramecium the most complex of the protists?

Paramecium is considered one of the most complex protists due to several reasons: Structure and cellular organization: Paramecium has a complex structure with cilia, or hair-like projections, covering its body. These cilia enable it to move and capture food. It also has a distinct organelle called the contractile vacuole, which helps regulate water balance within the cell. Its overall cellular organization, including specialized structures and organelles, is more advanced compared to other protists. Feeding mechanisms: Paramecium exhibits a sophisticated feeding mechanism. It has a specialized structure called the oral groove, lined with cilia, which helps sweep food particles into the mouth-like opening called the cytostome. It also possesses a food vacuole where digestion occurs. Reproduction: Paramecium has a complex reproductive system. It can reproduce asexually through binary fission, where the cell divides into two new individuals. Additionally, it can undergo sexual reproduction through a process called conjugation, where two individuals exchange genetic material. Behavioral responses: Paramecium is capable of complex behavioral responses, such as avoiding sources of light or harmful substances in their environment. They exhibit a coordinated response to stimuli known as taxis, which allows them to move towards favorable conditions and away from unfavorable ones. Genetic complexity: Paramecium possesses a relatively large and complex genome compared to other protists. It has multiple copies of some genes and exhibits gene regulation, allowing it to respond to different environmental conditions and adapt to changing circumstances. Overall, Paramecium showcases a higher level of structural complexity, specialized organelles, feeding mechanisms, reproductive strategies, and behavioral responses, making it one of the most complex protists.

How does a paramecium regulate its internal water concentration?

Paramecium is a single-celled organism that lives in freshwater environments. It needs to regulate its internal water concentration to maintain proper cell function and prevent excessive water influx or water loss. Paramecium primarily regulates its internal water concentration through a process called osmoregulation. Osmoregulation is the maintenance of a stable balance of water and solutes within the cell's cytoplasm, regardless of the external environment. The main mechanism of osmoregulation in paramecium involves the contractile vacuole. The contractile vacuole acts as a water pump, pumping excess water out of the cell to maintain the cell's internal osmotic pressure. - Water uptake: Paramecium takes in water through a process called endocytosis, where it opens its oral groove and engulfs food particles along with some water. This ingestion of water helps maintain an adequate water volume within the cell. - Contractile vacuole: Excess water that enters the cell is collected in the contractile vacuole. The contractile vacuole periodically fills with water from the surrounding cytoplasm. Once filled, the vacuole contracts and expels the excess water through a pore in the cell membrane called the cytoproct. The contractile vacuole functions as a water-regulating organelle, preventing the cell from filling up with too much water and potentially bursting. - Osmotic adjustment: Paramecium maintains the appropriate solute concentration within its cytoplasm to prevent excessive water influx or loss. It does this through various metabolic processes, such as active transport of ions and molecules across the cell membrane. This helps maintain the osmotic balance and water concentration within the cell. Overall, paramecium utilizes the contractile vacuole and osmotic adjustment mechanisms to regulate its internal water concentration. These processes ensure that the cell can function optimally and survive in its freshwater environment.

Which of the following statements concerning teams is true?

Unfortunately, you have not provided any options or statements to choose from. Could you please provide the statements so I can identify the true one?

What is the disease caused by paramecium?

Paramecium is a type of microscopic single-celled organism that is generally harmless to humans. However, it can be a potential cause of swimmer's itch, also known as cercarial dermatitis. This condition is caused by the larvae of certain parasitic worms that can be carried by paramecium and other similar organisms. When these larvae come into contact with human skin while swimming or wading in contaminated water, they can cause an itchy rash and other allergic reactions.

When yeast are grown on agar which term best describes the appearance of the colonies?

The term "colonial morphology" best describes the appearance of yeast colonies grown on agar.

Which one of these statements best describes the concept of line as it's used in design?

The statement "Line is a visual element that connects two points and creates a sense of movement, direction, and shape in design" best describes the concept of line as it is used in design.

What type of microscope would you use if you wanted to examine the movement of a freshwater protist?

If you want to examine the movement of a freshwater protist, you would typically use a compound microscope. The compound microscope is the most commonly used microscope in biology and allows you to view specimens using two or more lenses. This type of microscope provides high magnification and resolution, enabling you to observe the movement and structure of the protist in detail. You might also consider using a phase contrast microscope or a differential interference contrast (DIC) microscope, as these techniques can enhance the contrast and visibility of unstained protists.

Which of the following best describes a successful individual in evolutionary terms?

A successful individual in evolutionary terms is one that has a higher level of fitness.

What is a relationship between organisms that strive for the same limited resources?

The relationship between organisms that strive for the same limited resources is often referred to as competition. In this relationship, different individuals or species compete against each other for resources such as food, water, shelter, or mates. This competition can be intense, as each organism strives to outcompete others to secure the resources necessary for their survival and reproductive success. The competition can lead to adaptations, such as evolving techniques, physical attributes, or behaviors that enhance an organism's ability to access and utilize these limited resources.

Which statement best describes the evolutionary significance of mutualism?

The evolutionary significance of mutualism is that it provides benefits to both species involved, promoting coevolution and enhancing their chances of survival and reproduction.

Why is paramecium species used to investigate competition?

Paramecium species are commonly used to investigate competition in biology studies for several reasons: Easy to culture: Paramecium species, such as Paramecium aurelia and Paramecium caudatum, are relatively easy to culture in a laboratory setting. They can be maintained in simple growth media and replicated quickly, allowing for large-scale experiments. Rapid reproduction: Paramecium species have a short reproductive cycle, with a generation time of around 24 hours. This enables researchers to observe multiple generations within a reasonably short period, facilitating the study of long-term competition dynamics. High population density: Paramecium species can achieve high population densities in confined environments, making them suitable for studying competition. When resources become limited, Paramecium organisms can compete for availability, leading to observable effects on growth rates, population sizes, and other related parameters. Transparent body: Paramecium species possess a transparent body, which allows for easy microscopic observation of their internal structures and behaviors. This transparency is particularly advantageous when studying the interactions between individuals during competitive encounters. Amenable to manipulation: Paramecium species are amenable to various experimental manipulations, such as controlling their food availability, altering environmental conditions, or even genetically modifying them. These manipulations allow researchers to investigate specific aspects of competition and its underlying mechanisms. Combining these characteristics, Paramecium species serve as valuable model organisms to investigate competition and understand its implications in ecological dynamics and evolutionary processes.

Do paramecium caudatum can rapidly grow compared to the paramecium aurelia?

No, Paramecium aurelia can rapidly grow compared to Paramecium caudatum. Paramecium aurelia has a higher growth rate and reproduces more quickly than Paramecium caudatum. This is due to differences in their life cycle and reproductive strategies.

Which statement about competition is true?

There are multiple statements about competition that can be considered true, depending on the context. Here are a few possible true statements about competition: Competition can drive innovation and improve quality: When businesses or individuals compete with each other, it often leads to the development of new ideas, improvement in products or services, and higher standards within the industry. Competition can benefit consumers: Competition among businesses typically results in lower prices, increased variety of products or services, and better customer service, all of which benefit consumers. Competition can be both healthy and unhealthy: Healthy competition fosters growth, encourages individuals or businesses to strive for excellence, and adds excitement and inspiration to various fields. However, excessive or unfair competition can lead to detrimental effects such as market monopolies, unethical practices, and market imbalances. Competition is a natural part of human interaction: People naturally compete with one another in various aspects of life, including education, sports, career, and personal achievements. Ultimately, the true statement about competition depends on the specific context and the intended meaning behind it.

What do some paramecium have a symbiotic relationship with?

Some paramecium have a symbiotic relationship with certain species of bacteria. These bacteria live inside the paramecium and provide various benefits, such as helping with digestion, providing nutrients, and offering protection against harmful microorganisms. This mutualistic relationship benefits both the paramecium and the bacteria.

Which of the following best describes a symbiotic relationship between two organisms?

A symbiotic relationship is a close and long-term interaction between two different species that benefits at least one of the organisms involved. There are three types of symbiotic relationships: mutualism, commensalism, and parasitism. Mutualism: Both organisms benefit from the relationship. For example, the relationship between bees and flowers. Bees feed on nectar from flowers and, in the process, they transfer pollen from one flower to another, enabling plants to reproduce. Commensalism: One organism benefits while the other is neither harmed nor benefited. For example, a bird building its nest on a tree. The bird benefits from the shelter and stability provided by the tree, while the tree is unaffected. Parasitism: One organism benefits at the expense of the other. For example, ticks feeding on the blood of a host animal. The tick benefits from obtaining nutrients, while the host animal may experience adverse effects such as itching or the transmission of diseases. Therefore, the best answer would depend on the specific relationship being described.

Which of the following is a true statement about the effects of sugar?

a) Consuming excessive amounts of sugar can lead to weight gain and an increased risk of various health issues such as obesity, heart disease, and type 2 diabetes.

Which of the following best describes what it means to compete?

Competing generally refers to actively participating in a competition or contest in order to strive for victory or success. It often involves engaging in a rivalry or contest against others with the goal of outperforming them. Competing requires individuals or teams to demonstrate their skills, abilities, and strengths to differentiate themselves from others and achieve a competitive advantage. It may involve various aspects such as strategy, physical or mental prowess, adaptability, and resilience. Additionally, competition often implies a spirit of fair play, where individuals or teams follow and respect the rules and regulations governing the specific contest or competition.

Which of the following is not a characteristic of paramecium?

There are no options provided in the question, so I cannot determine which characteristic is not applicable to Paramecium. Please provide the options or specify the characteristic you are looking for.

Which of the following statements best describes carrying capacity?

Carrying capacity refers to the maximum number of individuals or amount of resources that an ecosystem or environment can sustainably support over a long period of time without causing detrimental effects to the population or the environment. It takes into consideration factors such as food availability, space, water, and other resources necessary for the survival and reproduction of a population. Essentially, it represents the limit at which an ecosystem's resources can support a population without causing environmental degradation or social disruption.

Which of the following statements describes the process of binary fission?

The correct statement describing the process of binary fission is: Binary fission is the method of asexual reproduction in which a single parent organism divides into two identical daughter cells, each with its own complete set of genetic material.

Which of the following is a true statement about the members of a species?

It would be helpful if you could provide the options you want me to choose from.

Does yeast finally have competition?

Yes, yeast finally has competition in the form of alternative sources of leavening agents or baking products. Some of the alternatives include: Sourdough starter: Sourdough bread is made using a naturally fermented starter, which contains wild yeasts and beneficial bacteria. It acts as a leavening agent, giving the bread its rise and flavor. Baking powder: Baking powder is a chemical leavening agent that consists of a combination of baking soda, cream of tartar, and sometimes cornstarch. It is commonly used in recipes that require a quick rise, like cakes and muffins. Baking soda: Baking soda, or sodium bicarbonate, is another chemical leavening agent that reacts with acidic ingredients like vinegar or lemon juice to produce carbon dioxide and create a rise in baked goods. Self-rising flour: Self-rising flour is a pre-mixed combination of flour, baking powder, and salt. It eliminates the need for yeast as a leavening agent and is commonly used for making biscuits and quick breads. Egg whites: Whipped egg whites can also act as a leavening agent by creating air pockets which expand during baking and give the baked goods a light and fluffy texture. These alternatives provide options for individuals with yeast allergies or those who prefer different flavors and textures in their baked goods. However, traditional yeast is still widely used and preferred for its specific flavor and texture it imparts to bread and other yeast-based products.

Which organelle is found in paramecia cells, but not plant cells?

Paramecium cells contain a variety of organelles, including some that are not found in plant cells, such as cilia, a contractile vacuole, and trichocysts.

Which of the following statements best describes the exclusion principle?

The Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers. This means that each electron in an atom occupies its own unique energy level.

Which of the following statements concerning complex multicellular organisms is true?

Complex multicellular organisms consist of many different types of specialized cells that work together to form the organism's organs and other structures.

Which of the these is not a true statement of the war exclusion?

act The War Exclusion Act was a law that allowed citizens of certain countries to enter the United States.

Which of the following statements is true of a worm?

A worm is a type of malicious software that replicates itself in order to spread to other devices connected to a network.

Which of the following statements is true of both membrane potential responses shown in the graphs?

Both membrane potential responses show a gradual decrease in magnitude over time.

What is the scientific name for paramecium?

The scientific name for paramecium is Paramecium caudatum.

Which of the following statements is true about lakes?

All of the following statements are true about lakes: -Lakes are bodies of fresh or saltwater surrounded by land. -Lakes are important habitats for a variety of plants and animals. -Lakes can provide many recreational activities, including fishing, boating, and swimming. -Lakes can also provide drinking water for people and other animals.

Which of the following statements regarding protozoa is false?

Protozoa are multicellular organisms.

Which of the following statements describing cilia is false?

Cilia can be used to ingest food particles.

Which organelle, within the paramecium, controls sexual reproduction?

The macronucleus controls sexual reproduction in the paramecium.

Which of the following is a true statement regarding engineering controls?

Engineering controls are used to reduce or eliminate workplace hazards by changing the way the job is done or by isolating the worker from the hazard.

Which is not observed in paramecium?

Paramecium, a single-cell microorganism, does not have nervous tissue or a nervous system, so it does not have a brain. Therefore, it cannot experience consciousness, thought, emotion, or cognitive processes, which are usually associated with a brain.

What is the dependent variable responses volume volume days days p. caudatum p. caudatum p. aurelia?

The dependent variable is the p. caudatum and p. aurelia.

Why does parameceum audralias overcome paramecium caudata?

Paramecium audralias is able to survive and compete better than Paramecium caudata due to its ability to tolerate higher temperatures and greater salinity. This makes it better suited to live in the warmer and saltier environment in which it is found. Furthermore, Paramecium audralias has a greater reproductive rate which allows it to out-compete Paramecium caudata.

Which of the following is not a true statement regarding lakes?

"Lakes contain saltwater" is not a true statement regarding lakes. Freshwater lakes are made up of freshwater, not saltwater.

Where does digestion take place in many protozoa?

Digestion in many protozoa takes place inside the cytoplasm of the cell where the food particles are broken down into smaller molecules by hydrolysis and other metabolic processes.

What phylum does paramecium belong to?

Paramecium belongs to the Phylum Ciliophora.

Which of the following statements is true about hunting laws?

? Hunting laws vary by country, state, and local jurisdiction, and they can change from year to year.

What protists move by means of many short, hairlike projections?

called cilia? Ciliates. Examples of ciliates include Paramecium, Euplotes, and Stentor.

Which of the following statements describes the members of a population?

Population members are individuals or groups of individuals who possess certain characteristics in common, including origin, language, ethnicity, gender, age, and occupation.

What structure allows paramecium to move?

Paramecium move by means of cilia, which are tiny hairlike structures that line the surface of the organism. The cilia beat in a coordinated fashion, allowing the paramecium to move forwards, backwards, and turn in any direction.

Which statement describes a species that is at carrying capacity?

A species at carrying capacity is a species that has reached the maximum number of individuals of that species that the environment can sustain.

How do the structures of the paramecium help it survive?

The cilia of the paramecium help it move and find food. Their contractile vacuoles help balance the internal osmotic pressure of the paramecium by pumping excess water out of the cell. The macronucleus controls the behavior and metabolism of the paramecium. The micronucleus is responsible for the sexual reproduction and exchange of genetic material. The gullet, or cytostome, helps the paramecium to ingest food.

What is true about paramecium?

Paramecium is a single-celled organism that is commonly found in freshwater habitats. It is a protozoan, meaning that it is a unicellular organism that is not classified as a plant, animal, or fungus. Paramecium is able to move around, reproduce, and feed on its own. It has a large nucleus and various organelles, making it more complex than bacteria.

Which of the two protists is better adapted to competition?

The answer depends on the type of competition being considered. Some protists may be better adapted to competing for resources, while others may be better adapted to competing for mates.

What classification of protists would include paramecia?

Paramecia belongs to the phylum Ciliophora, which is classified as a type of protist.

How does the contractile vacuole help the paramecium survive in a freshwater environment?

The contractile vacuole helps the paramecium to survive in a freshwater environment by actively pumping and expelling excess water from the cell to maintain a stable osmotic balance. The contractile vacuole works in conjunction with the cell membrane to regulate the amount of water entering and leaving the cell. This helps the paramecium maintain a proper level of hydration, and prevents the cell from becoming over-saturated, which could cause it to burst.

Which of the following is a true statement regarding the cold war?

The Cold War was a period of tension and hostility between the United States and the Soviet Union, and their respective allies, that lasted from the late 1940s to the early 1990s.

Which is a true statement regarding nutrients and energy in an ecosystem?

Nutrients and energy are essential for an ecosystem to function properly and are cycled among the organisms within the system.

Which of the following statements describes true motility?

Motility is the ability of an organism to move spontaneously and actively, using metabolic energy. It is an important factor in a number of biological processes, including cell motility, the movement of organisms, and the transportation of substances within cells.

Which of the following statements describes a worm?

accurately A worm is a type of malicious software that is self-replicating and can spread from one computer to another without user intervention.

What are the defense mechanisms found in paramecia called?

The defense mechanisms found in paramecia are called cilia and mucus. Cilia are tiny hair-like structures on the surface of the cell that help it to move. They also help the paramecium to filter out food particles from its surrounding environment. Mucus is a slimy substance produced by the cell that acts as a barrier between it and any potential predators. Both cilia and mucus play an important role in protecting paramecia from harm.

Where does digestion occur in a paramecium?

Digestion occurs in a paramecium through a complex process of phagocytosis, where the cell engulfs particles of food and breaks them down inside a food vacuole.

Why paramacium aurelia outcompete paramacium caudatum when they are kept in same culture tube?

Paramacium aurelia has larger size, higher motility, and larger ingestion rate than Paramacium caudatum. These attributes enable Paramacium aurelia to outcompete Paramacium caudatum for food and space, allowing it to dominate the culture tube.

What are the three graphs with p aurelia and p caudatum communicating?

Interaction Graph: This graph displays the density of the interactions between P. aurelia and P. caudatum. It shows how the two species interact with each other, such as the type of interactions (predation, competition, etc.), their frequency and the extent to which the two species influence each other in the environment. Species-Specific Abundance Graph: This graph displays the species-specific abundance of P. aurelia and P. caudatum. It shows how the two species are distributed across a given environment, as well as how their individual populations vary over time. Genetic Compatibility Graph: This graph displays the amount of genetic compatibility between the two species. It shows the degree of genetic interchange between the two species and can indicate the potential for hybridization or other genetic mixing.

How to compare two paramecium with each other cultured in different media?

To compare two paramecium cultured in different media, scientists can observe certain biological characteristics, such as size and shape, swimming behavior, feeding behavior, and reproductive behavior. Additionally, scientists can observe and record the differences in their response to certain external stimuli such as light, chemicals, and predator cues. They can also analyze the differences in their ability to survive in different habitats and environments. Finally, scientists can measure the relative growth and lifespan of the two paramecium in different media, and compare the results.

How does nutrition take place in paramecium?

Nutrition in Paramecium occurs through a process of phagocytosis, which is the process of engulfing and taking in particles of food. Paramecium has an oral groove that helps to draw in the food particles, which are then encased in a vacuole, where digestion occurs. Nutrients are then released from the food particles, and are incorporated into the organism’s cells. The digestive vacuoles also act as storage for waste products to be eliminated from the organism.

How does food reach inside the paramecium?

Food reaches the inside of a paramecium by way of its cell membrane. This is a selectively permeable membrane that allows certain substances to pass through while blocking others. The process of food entering the paramecium includes the following steps: 1) The food is taken into the paramecium by a process called endocytosis. In this process, the membrane of the cell will engulf the food and create a vacuole around it. 2) The vacuole then moves towards the center of the cell and fuses with a lysosome, which is an organelle containing digestive enzymes. 3) The digestive enzymes break down the food into simpler molecules that can be absorbed by the cell. 4) The molecules are then transported across the cell membrane and into the cytoplasm. 5) Finally, the molecules are taken up by the cell for energy and used for various metabolic processes.

What is the method of motility of paramecium?

Paramecium uses a type of motility called ciliary locomotion. This involves beating of the cilia, which are hair-like projections on the organism's outer membrane. The cilia beat in a coordinated fashion and create a water current that moves the paramecium through the water.

What type of cell is a paramecium?

Paramecium is a type of single-celled organism classified as a protist. It is a ciliate protozoan, meaning it is covered in hairlike projections called cilia.

Which of the following statements describes a response of predators to prey?

Predators will adjust their hunting strategies in response to changes in the population size of their prey.

Which of the following is a true statement regarding species richness?

Species richness is a measure of the number of species found in a given area.

Which factors contribute most to intraspecific competition?

Availability of resources: The availability of resources such as food, shelter, and space is a major factor that contributes to intraspecific competition. When resources are limited, individuals of the same species are forced to compete for them, resulting in a struggle for survival. Aggression: Aggression can also be a factor in intraspecific competition, especially in animals that establish territories or hierarchies. Aggressive behavior is often used to claim resources or defend them from other individuals. Reproduction: Reproduction is another factor that contributes to intraspecific competition. By competition for a mate, individual reproductive success is ensured. This can result in competition for the best habitat and even fights between males of the same species. Interference: Interference competition can also occur when individuals directly interfere with the activities of other members of the same species. This can involve blocking resources or preventing access to them, as well as physically pushing or intimidating another individual. Mimicry: Mimicry is a form of intraspecific competition in which one individual mimics the behavior of another. This is often used to gain access to resources that the other individual has or to deceive the other individual in some way.

What is true of paramecia?

Paramecia are single-celled organisms that belong to the kingdom Protista. They are found in freshwater, brackish, and marine environments. They are usually about 0.25 to 0.5 millimeters in size and are easily visible under a microscope. Paramecia are free-living organisms that can move independently and feed on bacteria, algae, and other small organisms. They reproduce asexually by binary fission.

Why can't the paramecium change shape?

Paramecium are single-celled organisms, and as such their cell wall and structure is rigid and not able to change significantly. They are also bound by the laws of diffusion, which prevent them from altering their shape even if they wanted to.

When interspecific competition has an outcome called competitive exclusion, _________.?

one species will out-compete the other species and eventually drive the other species out of the environment.

What is the food source for the paramecium bacteria rice agar sugar?

Paramecium bacteria do not feed on rice agar or sugar. They feed primarily on microorganisms, such as bacteria, algae, and protozoa.

What was the food source the bacteria ate other bacteria weak paramecium rice nothing?

Nothing. Bacteria are not known to feed on other bacteria, weak paramecium, or rice.

How does paramecium obtain its food?

Paramecium obtains its food by a process called phagocytosis. In this process, the paramecium uses its oral groove or receptacle to draw in particles, such as bacteria, algae, and other small organisms. It then engulfs the particles with its cell membrane, forming a food vacuole. The cellular organelles within the paramecium, such as lysosomes and endoplasmic reticulum, work together to break down the particles and absorb their nutrients.

Where does paramecium live?

Paramecium live in aquatic environments, such as ponds, lakes, rivers, and oceans. They can also be found in sewage, soil, and other moist environments.

Is paramecium a bacteria?

No. Paramecium is a type of protozoa, not a type of bacteria. Bacteria are a different type of microorganism.

What is the relationship between the two species shown below?

The two species shown below are predator and prey. The predator is consuming the prey.

What happened to p. caudatum in the mixed population on day 14?

On day 14 of the mixed population, the numbers of P. caudatum had declined significantly, indicating that the species was being outcompeted by the other species.

When p. aurelia was grown alone, how long did it take to reach carrying capacity?

When grown alone, it took the protist Paramecium aurelia approximately 4 weeks to reach carrying capacity.

Which of the following could be true of two different species that have a competitive relationship?

One species may outcompete the other for resources. One species may dominate a certain environment while the other is relegated to less suitable habitats. One species may outlive the other due to its greater reproductive success. One species may consume the other as prey. Both species may experience reduced population growth due to the competition.

How does paramecium obtain energy?

Paramecium obtain energy through a process called chemoautotrophic nutrition. This involves taking in inorganic compounds from their environment and converting them into energy through biochemical mechanisms. They use their cilia to absorb inorganic compounds such as ammonia, sulfide, and nitrates which are then broken down by enzymes in the paramecium's cytoplasm. They then convert the products into a usable form of energy.

What can we conclude about p. caudatum from this experiment?

Based on this experiment, it can be concluded that Paramecium caudatum can reproduce asexually, as evidenced by the fact that the single organism cloned itself multiple times. This is a common form of reproduction among members of the Paramecium genus. It can also be concluded that this species has a short life cycle and can adapt to a wide range of environmental conditions.

What is g.f. gause's competitive exclusion principle?

Gause's Competitive Exclusion Principle states that two species competing for the same resources cannot coexist in the same environment if the resources are limited. This is because one species will outcompete the other for resources, and ultimately drive the other species to extinction. This principle states that in a given environment, the number of species will remain constant and that certain species are better adapted to survive than others due to their competitive advantage.

What is the food source for the paramecium?

Paramecia typically feed on bacteria, algae, and small particles of organic matter. They can also absorb nutrients from the surrounding environment, or phagocytose small particles of food.

How does paramecium get energy?

Paramecium obtains energy by consuming bacteria, algae, and other small organic matter. They feed by using their cilia to create a whirlpool of water that pushes food particles into the cell. Once inside, the ingested particles are subjected to a process of digestion by vacuoles and lysosomes, which break down their contents into molecules that can be used by the cell.

Which of the following statements about intraspecific competition is false?

Intraspecific competition is always beneficial to the species.

How does paramecium grow?

Paramecium grows by a process known as binary fission. This is a form of asexual reproduction in which a single organism divides into two daughter cells. During binary fission, the cell replicates its genetic material and then splits into two identical daughter cells. The daughter cells are exact copies of the parent cell and are capable of performing the same functions. The whole process of binary fission takes anywhere from 15 minutes to an hour to complete.

What do paramecium use for defense?

Paramecium use cilia to defend against predators by forming a protective loricae- a curved, jelly-like coating around the cell's surface. This helps to decrease the speed of currents, making it more difficult for predacious organisms to capture them. Additionally, paramecium can use their rapid movement and light-sensing pigment to detect the presence of a potential predator and swim away.

What resource were the mixed paramecium competing for in this study food space water mates?

In the study, the mixed paramecium were competing for resources such as food, space, water, and mates.

When p. caudatum and p. bursaria are grown together:?

When P. caudatum and P. bursaria are grown together, they are known to form a symbiotic relationship. P. bursaria serves as the primary consumer, while P. caudatum feeds off of the organic compounds resulting from the digestion of the algal food source by P. bursaria. This symbiotic relationship allows both species to benefit from the relationship, as they are able to obtain resources they would not otherwise have access to, while also providing protection and shelter for the other species.

What is the relationship between paramecium aurelia and yeast?

Paramecium aurelia and yeast do not have a relationship. They are two distinct organisms from different taxonomic kingdoms. Paramecium aurelia is a single-celled protozoan organism and yeast is a single-celled fungus.

What prevents p caudatum from surviving with p aurelia?

P caudatum and P aurelia are different species which belong in separate genera. Thus, they are not able to physically interbreed, meaning that P caudatum is unable to survive with P aurelia.

Why interspecific competition has an effect on the relative population size of p.caudatum.?

Interspecific competition has an effect on the relative population size of P.caudatum because it competes with other species for the same resources. This competition can lead to a decrease in the size of P.caudatum's population due to decreased access to food, habitat, water, and other resources. Additionally, the competition may also lead to increased competition for other resources such as mates, which can further decrease the overall size of the P.caudatum population.

Why does p. aurelia population grows?

P. aurelia populations grow because of their ability to reproduce asexually through fission and because their environment often contains a variety of beneficial resources, including food and oxygen, which help them to survive and thrive.

Why are there more paramecium cells than didinium cells?

Paramecium cells reproduce much more quickly than didinium cells. Paramecium also has a larger population to start with, while didinium usually only exist in a few isolated locations. In addition, didinium tends to feed on much larger prey than paramecium, so it may be more difficult for didinium to find enough food to sustain its population.

Who is the dominant organism between p. aurelia and p. caudatum?

It is not possible to answer this question definitively as it depends on the specific environment and competition between the two species.

What competitive advantage does paramecium aurelia has over paramecium caudatum?

Paramecium aurelia has several competitive advantages over Paramecium caudatum: Speed: Paramecium aurelia is generally faster in terms of locomotion compared to Paramecium caudatum. This increased speed allows it to quickly move away from predators or capture prey more effectively. Reproduction rate: Paramecium aurelia has a higher reproductive rate, producing more offspring in a shorter period of time. This allows it to quickly repopulate and outcompete Paramecium caudatum in environments with limited resources. Genetic diversity: Paramecium aurelia has higher genetic diversity due to its ability to undergo both sexual and asexual reproduction. This genetic variability provides an advantage in adapting to changing environmental conditions and overcoming challenges. Predator resistance: Paramecium aurelia has developed various defensive mechanisms to protect itself from predators, including cilia movement and the ability to change direction rapidly. These adaptations make it harder for predators to capture and consume Paramecium aurelia compared to Paramecium caudatum. Overall, Paramecium aurelia's advantages in speed, reproduction rate, genetic diversity, and predator resistance give it a competitive edge over Paramecium caudatum in various ecological niches.

Are paramecium aurelia and paramecium caudatum two different species?

Yes, Paramecium aurelia and Paramecium caudatum are two different species. They belong to different genera and can be distinguished by their different shapes. Paramecium aurelia has a slipper-like form with a rounded anterior end and a pointed posterior end, while Paramecium caudatum has a more ovoid form with a tapered anterior end and a contractile vacuole at the posterior end. They also differ in the number of cilia they possess; Paramecium aurelia has a single row of cilia while Paramecium caudatum has two rows of cilia.

Do paramecium use exploitative competition?

No, paramecium do not use exploitative competition. Exploitative competition is a type of competition that occurs between organisms of different species.

What type of competition exist between paramecium aureria and paramecium caudatum?

Competition between Paramecium aureria and Paramecium caudatum exists in the form of resource competition. Both species compete for food, light, and space. They also compete for mates, and may utilize different mating strategies to outcompete one another.

Is p. caudatum and p.aurelia same species?

No, Paramecium caudatum and Paramecium aurelia are two different species within the Paramecium genus.

Why cant p. aurelia p. caudatum coexist?

P. aurelia and P. caudatum cannot coexist because they are competing for the same resources in the environment. P. aurelia is a more aggressive species that is better adapted to its environment, so it is able to outcompete P. caudatum for food and other resources.

Why are p.aurelia better adapted than p caudatum?

P. aurelia is better adapted than P. caudatum because it is more resilient to changes in its environment. P. aurelia has the ability to break down into multiple smaller organisms when there is a decrease in food or space or when the environment becomes hostile. This allows P. aurelia to survive in harsh conditions, whereas P. caudatum cannot break down into smaller organisms and therefore is less able to survive in difficult conditions. P. aurelia also is more tolerant to temperature fluctuations, whereas P. caudatum is more limited when it comes to temperature fluctuations.

What advantages does paramecium aurelia have over paramecium caudatum?

Paramecium aurelia has a number of advantages over Paramecium caudatum, including: Greater resistance to environmental stress. Increased metabolism. Better reproduction rates. More genetic variability. Ability to form diverse cyst types. Ability to form polycultures. Average body size is larger. More flagella per cell. Greater tolerance for crowding. Easier to culture in laboratory settings.

What was the outcome when paramecium caudatum and p. aurelia competed in the same test tube?

When Paramecium caudatum and P. aurelia competed in the same test tube, the P. caudatum population grew more quickly and eventually outcompeted the P. aurelia population.

Why do paramecium aurelia and caudatum have different carrying capacities?

The carrying capacity of a species is determined by a variety of environmental and physiological factors, such as the availability of food and suitable habitat, the number of predators, and the species' physiological limitations. Paramecium aurelia and caudatum may have different carrying capacities because they have different adaptations and tolerances to their environment. For example, Paramecium aurelia is better adapted to living in warmer, more acidic waters, while Paramecium caudatum can tolerate changes in temperature and pH levels more easily.

What is gause experiment of competition in paramaecium aurelia caudatum?

Gause’s experiment of competition in Paramecium aurelia caudatum is an example of how two closely related species may compete for resources in a given environment. Gause used two strains of Paramecium aurelia caudatum, one which was more active and the other which was less active, and placed them together in a flask. He found that the more active strain consistently outcompeted the less active strain and was able to use resources more efficiently. This experiment suggests that competition can influence the evolution of species if resources are limited.

How to determine whether p.aurelia and p.caudatum will be mixed together?

The only way to determine whether P. aurelia and P. caudatum will be mixed together is to conduct laboratory experiments to observe their behaviors in response to each other. Factors such as size, motility, and habitat preferences would need to be considered in order to determine whether the two species can coexist in the same environment. Additionally, studying the physical characteristics of each species and monitoring their interactions would provide useful insights into whether they can be mixed together.

What competition is demonstrated in the paramecium lab?

Competition in the paramecium lab is demonstrated between different species of paramecium. As they compete for resources, such as food and space, the species with the greatest reproductive success will survive and thrive while the other species may become extinct.

What does paramecium caudatum and paramecium aurelia feed on?

Paramecium caudatum and Paramecium aurelia feed on a variety of organic matter, including bacteria, algae, small pieces of plants, and even small protozoans. They also feed on certain inorganic materials, such as mineral particles and diatoms.

Which competition in paramecium cwote dom and paramecium aurelia?

Competition between Paramecium cwote dom and Paramecium aurelia occurs mainly when resources become limited in their environment. The competition is based on competition for food sources such as bacteria, yeasts, and other protists, as well as competition for space in the environment. This competition can be an important factor in determining which species thrives in a given environment.

What is the difference between paramecium aurelia?

Paramecium aurelia is a species of single-celled protists belonging to the genus Paramecium. It is a widely studied organism, used as a model organism in studies of cellular biology and genetics. There is a great deal of variation within the species, and two distinct forms of P. aurelia are recognized. The first form, P. aurelia form I, is commonly referred to as the “solitary” form, while the second form, P. aurelia form II, is commonly referred to as the “social” form. The primary difference between these two forms is that the solitary form lives as isolated cells while the social form lives as colonies that can contain up to several hundred cells. In addition, the social form is capable of asexual reproduction by transverse binary fission, whereas the solitary form cannot reproduce asexually.

How do paramecium Compete?

Paramecium compete for resources such as food, space, and mates. They typically compete with other protists, bacteria, and microorganisms for these resources. To compete, they use various strategies such as predation, outcompeting for resources, and co-existing with other species. They also take advantage of their ability to move around quickly and efficiently to outmaneuver their competitors.

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WLF 448: Fish & Wildlife Population Ecology

Lab 14: competition, i. objectives of lab.

Become familiar with the classic work of G. F. Gause (Gause 1934).

Analyze data from Gause's experiment with 2 species of Paramecium   ( P. caudatum and P. aurelia ) to investigate:

a.  Is there evidence for intra specific competition?

b.  Is there evidence for inter specific competition?

c.  What are the implications for coexistence?

II. Definitions and Concepts

Competition occurs when animals utilize common resources that are in short supply; or if resources are not in short supply, competition occurs when the animals seeking those resources nevertheless harm one another in the process (Birch 1957). Interspecific competition occurs when two or more species experience depressed growth rate or equilibrium population level attributed to their mutual presence in an area (Emlen 1973). neutralism :  neither species is adversely affected by the other's presence amensalism :  individuals of only one species are adversely affected by the other's presence competition :  both species are adversely affected by the other's presence This brings up 3 important points: The interaction between two species will be reciprocal , i.e., causing demonstrable reductions in survival, growth, or fecundity of each species. However, one species often is more negatively affected than the other. A resource is in short supply. Even if animals overlap completely in resource utilization, competition usually does not occur unless a resource is limited in some way. The implication of #2 is that competition is density dependent .

    Types of Competition (Park 1962)

Interference competition – includes aggressive interactions in which one individual actively attempts to exclude another (e.g., blue jay domination of a bird feeder).

Exploitation competition – indirect competition in which one species uses more of the limited resource or uses the resource more efficiently than another species (e.g., cattle and elk on open range).  Exploitative competition can result in depletion of a resource by a species or it may involve some activity that makes the resource virtually valueless to another species.

III. Competition Models

A. intraspecific competition.

Growth rate is affected by the abundance of the same species

        ** Remember for stochastic exponential growth with process noise the model was:

ln[N t+1 /N t ] =  r t = a + F t

 where F t ~ normal (0, sigma 2 )

and Ricker-type density dependence (i.e., intraspecific competition) was:

ln[N t+1 /N t ] =  r t = a + b *N t   + F t

This is the Stochastic Ricker (logistic) Model where a and b  are estimated parameters, and b measures the magnitude of intraspecific competition.

Our estimate of carrying capacity ( K ) is:

B. Interspecific competition

Growth rate is affected by the abundance of another species

ln[N t+1 /N t ] =  r t = a + b *N t   + c *N t (other species) + F t

This is the Stochastic Ricker (logistic) Model with Competition where a , b, and  c  are estimated parameters, b measures the magnitude of intraspecific competition, and c measures the magnitude of interspecific competition.

Our estimate of carrying capacity ( K ) is: K = -[ a + c *N t (other species) ] / b

So, the carrying capacity is dependent on the abundance of the other species.

C. "Zero-growth isoclines" and "Phase-planes" for species 1 and species 2

D. Predicting the outcome of competition:

The expected outcome of competition can be examined by superimposing the phase-plane diagrams for each species

Note: There are 4 possible outcomes based on the 4 ways that the zero-growth isoclines can be arranged:

IV.  References

    1)    Birch, L. C.  1957.  The meanings of competition.  The American Naturalist 91:5-18.

    2)    Emlen, J. M.  1973.  Ecology: an evolutionary approach.  Addison-Wesley, Reading, Massachusetts, USA.

    3)    Gause, G. F.  1934.  The struggle for existence.  The Williams and Wilkens Co., Baltimore, Maryland, USA.

    4)    Park, T.  1962.  Beetles, competition, and populations.  Science 138:1369-1375.

Revised : 29 November 2010

Gause’s Law

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• First Online: 01 January 2022
• pp 2871–2877
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• Vincent Barnett 3  

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Gause’s exclusion law ; Gause’s principle ; Grinnell’s axiom ; The competitive displacement principle ; The competitive exclusion principle

Gause’s law is a principle in the field of population dynamics first outlined by Russian/Soviet biologist G.F. Gause, which states that two species that are competing for the same limited resources cannot coexist at constant population values, that no two species with similar ecological niches can coexist in a state of stable equilibrium, or that realized ecological niches do not intersect. It is otherwise called the competitive exclusion principle (CEP). Three different basic outcomes have been specified: competitive exclusion, local extinction, and niche differentiation.

Introduction

Population dynamics is a field that studies the change in the prevalence of different species over time in relation to four key life-path processes: birth, death, immigration, and emigration. Prior to Gause, after the initial nineteenth-century...

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Barnett, V. (2022). Gause’s Law. In: Vonk, J., Shackelford, T.K. (eds) Encyclopedia of Animal Cognition and Behavior. Springer, Cham. https://doi.org/10.1007/978-3-319-55065-7_2100

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Competitive Exclusion Principle

AUSTRALIAN CURRICULUM ALIGNMENT 

  Relationships and interactions between species in ecosystems include predation, competition, symbiosis and disease

BACKGROUND 

The competitive exclusion principle, or Gause’s law, proposes that two species competing for the same limited resources cannot sustainably coexist or maintain constant population values. Intraspecific competition describes organisms within the same species competing for resources, leading the population to reach carrying capacity. Carrying capacity refers to the maximum population size a species can sustain within its environmental limitations. Interspecific competition describes competition for resources between different species of organisms. Species can be limited by both their carrying capacity (intraspecific competition) and the interspecific competition. When two species compete within the same ecological niche, the competitive exclusion principle predicts that the better-adapted species, even if only slightly better adapted, will drive the other to local extinction. In the 1930s, biologist Georgy Gause explored the idea of interspecific competition in a ground-breaking study of competition in Paramecium . Paramecia are aquatic single-celled ciliates that survive on a diet of bacteria, yeast, algae and other small protozoa. Based on the findings of this experiment and other research, Gause developed the competitive exclusion principle.

In this investigation, students explore how competition affects population growth, and put the competitive exclusion principle to the test. Following a very similar experiment design to Gause’s original Paramecium experiment, students examine two Paramecium species; Paramecium Caudatum and Paramecium Aurelia . These two species make great model organisms to test this principle due to their similarity, and the fact they compete directly for food. However, the two vary in size, with Paramecium Caudatum approximately four times the size of Paramecium Aurelia . Students are tasked with growing the two species both separately and together in a culture medium. The three cultures samples are maintained within the exact same environmental conditions, as Gause's law only applies if the ecological factors are constant. Over three weeks, students observe population growth to determine how competition for resources affects population growth.

PREPARATION  - BY LAB TECHNICIAN

Preparing Cultures

• As soon as your shipment arrives, open the shipping container, remove the Paramecium culture jars, and inspect your culture. Loosen the lids on the containers .
• Aerate the culture using a plastic pipette. To do this, hold the pipette tip into the culture water and squeeze the bulb. Raise the pipette and release the bulb; allowing it to fill with air once again. Repeat this step four more times to assist in replacing the oxygen depleted during shipping. Use a different pipette for each culture to avoid contamination.

Lightly place the lid back on the containers; careful not to screw too tightly. Maintain the culture jar within room temperature (Approx. 21°C), away from direct sunlight. Plan to conduct your experiment with the Paramecium within three days of your shipment arriving. Ensure you have sufficient Paramecium for each student and take into account that some Paramecium may die.

METHOD  - STUDENT ACTIVITY

• State your hypothesis.

Label three clean Petri dishes A, B and C.

• Add 50mL of Paramecium culture medium to each dish. 
• Using a graduated cylinder, transfer 20 mL of Paramecium aurelia into Petri dish A. 
• Transfer10 mL of Paramecium caudatum and 10 mL of Paramecium aurelia into Petri dish B. 
• Transfer 20 mL of Paramecium caudatum into Petri dish C. 
• Add six grains of rice to each dish.
• Cover each of the Petri dishes containing the Paramecium cultures with cheesecloth.
• Store the Petri dishes at a consistent temperature of 24°C on a flat surface where they will not be disturbed. Keep away from direct sunlight.
• Using a fresh sterile pipette, place 1 mL of liquid from each sample in a Sedgewick Rafter cell. 
• Using a compound microscope, count the relative number of Paramecium of each species in each Petri dish. 
• Repeat the count every second day for 3 weeks.

OBSERVATION AND RESULTS

Below is an example of expected results based on initial population density of Paramecium were 10 per 1 mL. This is to be used as a guide only as individual results will vary. 

• Plot your results as a line graph.
• Plot the growth of each species in Petri dish C on the same axes, with time (every 2 days) on the x-axis and population size (Paramecium per 1 mL) on the y-axis.
•   Combine your results with the rest of the class to get class results.
•   Plot the class results as a line graph.
•   Describe what has occurred in populations A, B and C. Identify whether the populations increased or decreased or remained stable.

INVESTIGATIONS

Was your hypothesis supported? Provide reasons.

• What are the advantages and disadvantages of this counting technique?
• What are some limitations in the experiment design? Suggest how it might be improved.
• Compare the population sizes of each Paramecium species in the separated (A and B) and mixed cultures (C). What do the results reveal about how competition affects population growth?
• Do your results support or refute the competitive exclusion principle? Provide evidence from your results.
• Did the trends in the class results differ from your own results?

EXTENSION EXERCISES

Exponential growth describes population growth that is unlimited. Logistic growth describes growth rates that are limited by a number of factors, including predators and food scarcity as well as competition for food and habitat. Which type of growth was exhibited in the Paramecium populations containing only one of the species? Determine the carrying capacity of the organism in this model environment.

TEACHING NOTES

Demonstrate the correct method of preparing the Paramecium cultures in the petri dish before students begin the procedure.  

• Students may be tempted to add too much rice to each petri dish; however, inform students that 6 grains of uncooked rice will be sufficient.
• Ensure students understand the importance of following the exact same procedure for each culture, to generate the most accurate results possible. Instruct students to add the exact same measurement of cultures to each petri dish; add the same number of rice grains; use the same method for counting; and maintain the culture within the same environmental conditions. Environmental conditions include access to light and temperature.  
• There are quieting solutions, such as Protoslo®, available that will allow you to slow the organism’s movement without damaging them. This makes it easier for students to count the Paramecium culture under the microscope.  

Time Requirements

• 50 mins  

Material List

• Pure cultures of Paramecium Caudatum  
• Pure cultures of Paramecium Aurelia  
• Paramecium Culture Medium  
• Grains of rice  
• 3 Deep Petri Dishes  
• Sedgewick Rafter Cell
• Graduated Cylinder
• Mosquito Net/Cheese Cloth
• Sterile Plastic Pipettes
• Compound Microscope

 Safety Requirements

Wear appropriate Personal Protective Equipment (PPE), including gloves and lab coat.  

• Paramecia are harmless to humans, but swamp or pond water may contain pathogens. Wash hands thoroughly before and after handling living specimens.

||Biology||Classroom Practicals||Biodiversity||Year 11&12||

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Research Article

Gause's Principle and the Effect of Resource Partitioning on the Dynamical Coexistence of Replicating Templates

Affiliations Department of Plant Systematics, Ecology and Theoretical Biology, Institute of Biology, Eötvös University, Budapest, Hungary, Department of Plant Systematics, Ecology and Theoretical Biology, Research Group of Ecology and Theoretical Biology, Eötvös University and The Hungarian Academy of Sciences, Budapest, Hungary, Parmenides Center for the Conceptual Foundations of Science, Munich/Pullach, Germany

Affiliation Parmenides Center for the Conceptual Foundations of Science, Munich/Pullach, Germany

* E-mail: [email protected]

• András Szilágyi, 
• István Zachar, 
• Eörs Szathmáry

• Published: August 22, 2013
• https://doi.org/10.1371/journal.pcbi.1003193
• Reader Comments

Models of competitive template replication, although basic for replicator dynamics and primordial evolution, have not yet taken different sequences explicitly into account, neither have they analyzed the effect of resource partitioning (feeding on different resources) on coexistence. Here we show by analytical and numerical calculations that Gause's principle of competitive exclusion holds for template replicators if resources (nucleotides) affect growth linearly and coexistence is at fixed point attractors. Cases of complementary or homologous pairing between building blocks with parallel or antiparallel strands show no deviation from the rule that the nucleotide compositions of stably coexisting species must be different and there cannot be more coexisting replicator species than nucleotide types. Besides this overlooked mechanism of template coexistence we show also that interesting sequence effects prevail as parts of sequences that are copied earlier affect coexistence more strongly due to the higher concentration of the corresponding replication intermediates. Template and copy always count as one species due their constraint of strict stoichiometric coupling. Stability of fixed-point coexistence tends to decrease with the length of sequences, although this effect is unlikely to be detrimental for sequences below 100 nucleotides. In sum, resource partitioning (niche differentiation) is the default form of competitive coexistence for replicating templates feeding on a cocktail of different nucleotides, as it may have been the case in the RNA world. Our analysis of different pairing and strand orientation schemes is relevant for artificial and potentially astrobiological genetics.

Author Summary

The dynamical theory of competing templates has not yet taken the effect of sequences explicitly into account. One might think that complementary sequences have very limited competition only. We show that, despite interesting sequence effects, competing template replicators yield to Gause's principle of competitive exclusion so that the number of stably coexisting template species cannot exceed the number of nucleotide species on which they grow, although one of the findings is that plus and minus strands together count as one species. Thus up to four different templates/ribozymes can constitute the first steps to an early, segmented genome: we suggest that other mechanisms build on this baseline mechanism.

Citation: Szilágyi A, Zachar I, Szathmáry E (2013) Gause's Principle and the Effect of Resource Partitioning on the Dynamical Coexistence of Replicating Templates. PLoS Comput Biol 9(8): e1003193. https://doi.org/10.1371/journal.pcbi.1003193

Editor: Claus O. Wilke, University of Texas at Austin, United States of America

Received: February 13, 2013; Accepted: July 5, 2013; Published: August 22, 2013

Copyright: © 2013 Szilágyi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: Financial support has been provided by the European Research Council under the European Community's Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement no [294332] ( http://erc.europa.eu ) and the Hungarian National Office for Research and Technology (NAP 2005/KCKHA005) ( http://www.nih.gov.hu ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

We explicitly take into consideration the concentration of up to four different building blocks (“nucleotides”, with the aim that the model should be general enough to deal with different number of bases and base-pairing modes [13] – [15] ) and a large number of competing different sequences, in order (i) to present, at least in part, the missing theory of competing template replicators having different sequences and (ii) to answer the question whether Gause's principle holds for such replicators.

During the forthcoming analysis we deliberately introduce some simplifications. We assume that template replication rates depend on nucleotide concentration linearly (there are no cooperative effects) and that the dynamics of these abiotic resources are not periodically forced, for example. We neglect replicase enzymes and assume that template and replica separate irreversibly upon completion of elongation. The kinetic effects are simplified to the extent that the elongation rate of template polymerization depends only on the identity of the inserted nucleotide and nothing else. We know that this is a crucial simplification but already with this rule different sequences may assume very different kinetic phenotypes. In agreement with this, we neglect secondary and tertiary structures.

Some of the effects that we show in this paper are far from trivial. Our calculations show the effect of resource partitioning on template coexistence and shed more light on early molecular evolution, which surely was affected by sequence effects of template replicators.

To understand the mechanism of coexistence of template replicators ( sequences ) we formulated the dynamics of polynucleotide replication. Here we only explain the necessary basics of our formalism, for the mathematical model see Models Section, for further details see Text S1 . Template replicators are assumed to be single-stranded with double-stranded replication intermediates (as for RNA). As a simplification, metabolism responsible for replication is restricted to the common pool of shared monomers, which are either fed from within (protocells) or from the outside (flow reactor).

First, we investigate the more realistic but also more complex systems that can only be solved numerically and later we gradually traverse to simplified systems that can be handled fully analytically. Such systems, though simplified, provide powerful rules about the mechanisms of coexistence which still can be translated and applied to the realistic cases. Accordingly, first we numerically analyze the complementary replication of templates corresponding RNA replication. Second, we deal with the simpler homologous replication where monomers pair with identical types (non-complementary base-pairing); we also introduce parallel strand polarity as opposed to antiparallel polarity (like in case of RNA replication). The difference between complementary and non-complementary pairing and parallel and antiparallel strand polarity is given in Fig. 1 . Third, as a further simplification of the previous system, we assume uniform degradation rates for replication intermediates and even identical elongation rates for the different monomer types to obtain analytical results.

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

Reverse (top left) and direct palindromes (bottom middle) yield two identical templates with complementary and homologous pairing, respectively, just like homologous pairing with parallel polarity. Note, that in case of reverse palindromes, it is not necessary for the sequence itself to be palindromic to make the two strands identical. Cases of complementary pairing with antiparallel polarity (top left and middle) and homologous pairing with parallel polarity (bottom right) are discussed in the main text; homologous pairing with antiparallel polarity (bottom left and middle) is discussed in Text S1 . The remaining case (top right) is not discussed here.

https://doi.org/10.1371/journal.pcbi.1003193.g001

Complementary replication

https://doi.org/10.1371/journal.pcbi.1003193.t001

https://doi.org/10.1371/journal.pcbi.1003193.t002

https://doi.org/10.1371/journal.pcbi.1003193.g002

Non-complementary (homologous) replication

Non-uniform degradation rates.

As there is no complementary pairing or polarity, any sequence pair consists of two identical sequences, thus the maximum number of coexisting species on two different resources is expected to be two. With the applied restrictions, the system still remains overly complex for an analytical approach (see the next two sections for an analytically tractable simplification). According to our exhaustive numerical results, we have found no case where more than two sequences could coexist, supporting our hypothesis. We have numerically integrated ODE systems until convergence or extinction of one of the sequences. The numerical methods and routines are the same as before. We have analyzed the coexistence of two sequences in two different ways (for parameters see Text S1 ):

First, the results of our investigations according to method M3 can be found in Table 3 . It can be observed that approximately half of the sequences coexist, independent of the sequence length, while increasing length decreases the mean stability (defined as the mean of leading eigenvalues). We have always found coexistence to be locally asymptotically stable.

https://doi.org/10.1371/journal.pcbi.1003193.t003

https://doi.org/10.1371/journal.pcbi.1003193.t004

https://doi.org/10.1371/journal.pcbi.1003193.g003

https://doi.org/10.1371/journal.pcbi.1003193.g004

Uniform degradation rates.

We have demonstrated numerically, that more than two arbitrary sequences are able to coexist, though in a structurally unstable way: any perturbation of the degradation rates destroys coexistence, rendering the system to a simpler one where only one or two sequences coexist on the two monomers. Thus Gause's principle is not violated.

Uniform degradation rates and identical rate constants.

To sum up, according to the coexistence condition ( Eq. (15) ), the front part of the sequence ( head ) weighs more concerning the coexistence than the rear ( tail ). This is because during replication, earlier intermediates are present in larger concentrations than intermediates closer to the final step of the replication (for details, see Text S1 ). Consequently, monomers included earlier (i.e. into the head) are needed in higher concentrations than monomers incorporated into the tail. Thus the head influences competition more strongly than the tail.

In this paper we have provided the foundations of the hitherto missing theory of template replication where replication intermediates and different sequences are explicitly taken into account. Under the assumption of fixed stable steady state densities for resources and competitors Gause's principle [1] fully rules over replicator dynamics: coexistence of more replicators than the number of limiting resources (nucleotides) is not asymptotically stable. We have found, however, that template and copy (or plus and minus strands) count as one replicator, since they are stoichiometrically coupled.

We have found cases of coexistence where Gause's principle seems to be violated in that two sequences can coexist with exactly the same nucleotide composition but adequately different sequences: this is a version of the stage-structure effect on coexistence found in theoretical ecology [16] . The part of a sequence that is replicated earlier has a stronger effect than that replicated later, since replication intermediates corresponding to positions in the front are more abundant, hence they influence competitive dynamics more strongly. We have demonstrated the trend that the stability of coexistence in terms of the leading eigenvalue decreases with sequence length. This may be considered bad news; however we should not forget that a good share of ribozymes [18] and aptamers [19] is smaller than 100 nucleotides, for which one still would get acceptable local stability values. (Note that the smallest known ribozyme consists of 5 nucleotides [20] .)

Recently there has been an upsurge in interest in exo/astrobiology. It is in this context that we have deliberately presented results for homologous pairing also, even with parallel orientation of the strands. Although such configurations are not unheard of even in our world, we wanted to see how such features would in general affect dynamical coexistence of template replicators.

We have obtained the fitness landscapes through a distribution of elongation and degradation rates. The main reason behind this is tractability: although the 2D structures as phenotypes of RNA molecules can be calculated for most cases, this does not automatically yield phenotypes in terms of replication rates. We are temporarily satisfied with the phenotype richness that our local rules provided (see Fig. S3 ). What is more, we predict that the main finding that Gause rules over competitive coexistence of template replicators in stable steady state would not be violated even with more complex fitness landscapes.

Reaction and dynamics

The extension of the dynamics for more sequence pairs (i.e., to more than one copy and template) is straightforward. The dynamics of the intermediates is independent for each pair and the dynamics of the monomers provides the coupling between the equations of different pairs of sequences. Because of the cross-coupling of equations, no analytical solution was found (some analytical results will be presented for simplified cases). For the numerical integration of the ODE system to find steady-state solutions we have used the CVODE code from the SUNDIALS project of the Lawrence Livermore National Laboratory [27] .

Non-complementary replication and uniform degradation: An analytical approach

Supporting Information

https://doi.org/10.1371/journal.pcbi.1003193.s001

https://doi.org/10.1371/journal.pcbi.1003193.s002

https://doi.org/10.1371/journal.pcbi.1003193.s003

https://doi.org/10.1371/journal.pcbi.1003193.s004

https://doi.org/10.1371/journal.pcbi.1003193.s005

https://doi.org/10.1371/journal.pcbi.1003193.s006

https://doi.org/10.1371/journal.pcbi.1003193.s007

https://doi.org/10.1371/journal.pcbi.1003193.s008

Supporting text with sections on 1) Parameters for methods M1, M2, M3 and M4; 2) Analysis of non-complementary pairing with antiparallel polarity; 3) Analysis and analytical results of non-complementary pairing and uniform degradation rates; 4) Proofs; 5) Discussion of the fitness landscape; 6) Examples of coexistence of longer sequences.

https://doi.org/10.1371/journal.pcbi.1003193.s009

Acknowledgments

Comments by Drs I. Scheuring and B. Könnyű are gratefully acknowledged.

Author Contributions

Conceived and designed the experiments: AS IZ ES. Performed the experiments: AS IZ ES. Analyzed the data: AS IZ ES. Contributed reagents/materials/analysis tools: AS IZ ES. Wrote the paper: AS IZ ES.

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[Analysis of G.F. Gause experimental time-series by means of continuous-time models]

• PMID: 22590906

Four population dynamics models, namely Verhulst, Gompertz, Rosenzweig, and Svirezhev ones, have been used to approximate two well-known time-series of Paramecia aurelia and P. caudatum population size (Gause, 1934). The parameters are estimated for each of the models by the least-square method (with global fitting) in two different ways: with and without an additional upper bound for a parameter value. In the latter (traditional) case, when the deviations of theoretical (model) trajectories from experimental time-series have been tested for normality (Kolmogorov-Smirnov test, Shapiro-Wilk test) with zero average, and for the presence/absence of serial correlations (Durbin-Watson criteria), the best results are obtained for the Gompertz and Verhulst models. In the former, more realistic, case (when we impose an additional constraint that the parameter meaning the carrying capacity of the environment has to be greater than any element in the sample), the best results are observed for the Gompertz model. Under this constraint, the canonical technique for deviation analysis can be applied in a restricted version only.

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