Biology Competition Concepts

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Questions and Answers

What can abiotic conditions affect in competitive interactions?

The reproductive rates of all species involved

The feeding habits of herbivores

The carrying capacity of a species (correct)

The genetic diversity of competitive species

Which of the following best describes the trade-off seen in Chthamalus and Semibalanus barnacles?

Chthamalus is more resilient to desiccation (correct)

Semibalanus survives better when resources are limited

Chthamalus is a better competitor for space

Semibalanus can withstand harsh abiotic conditions

How do disturbances such as fires affect competitive interactions?

They always favor larger fire-resistant plants

They can prevent certain plants from outcompeting others (correct)

They increase the overall competition among all species

They have no effect on species composition

What is a common outcome when predators are present in an ecosystem?

The most competitive organisms are often preyed upon more Signup and view all the answers

What was the result of adding predatory newts to tanks with tadpoles in the study?

Docile peepers survived better when many predators were present Signup and view all the answers

What effect do herbivores have on competition, as demonstrated by studies on goldenrod?

Insect outbreaks can increase the survival of other plant species Signup and view all the answers

Why might certain species not reach their carrying capacity in a competitive environment?

Abiotic factors or interspecific interactions may hinder them Signup and view all the answers

What is a potential consequence of fire suppression in ecosystems?

Reduction in species that thrive in fire-heavy environments Signup and view all the answers

How can the outcomes of competition be altered?

By abiotic conditions, disturbances, and interspecific interactions Signup and view all the answers

What defines competition among individuals in an ecosystem?

An interaction that has a negative impact on both individuals Signup and view all the answers

Which type of competition occurs within the same species?

Intraspecific competition Signup and view all the answers

Which of the following is considered a renewable resource?

Sunlight Signup and view all the answers

What is the main idea behind Liebig's law of the minimum?

A population increases until the supply of the most limiting resource restricts it. Signup and view all the answers

Which of the following scenarios exemplifies the competitive exclusion principle?

One species dominates when competing for the same limited resource. Signup and view all the answers

In the context of resource competition, what is meant by apparent competition?

Competition that arises from shared predation Signup and view all the answers

What term describes competition between different species?

Interspecific competition Signup and view all the answers

How can abiotic conditions influence competition outcomes?

By altering species interactions and resource availability Signup and view all the answers

What is a characteristic of non-renewable resources?

They are typically fixed in quantity. Signup and view all the answers

Which of the following resources could be considered a limiting factor for population growth?

Oxygen for terrestrial animals Signup and view all the answers

How does competition for renewable resources typically affect species?

It reduces both the abundance and the rate of resource supply. Signup and view all the answers

In the experiment with small balsam (Impatiens parviflora), what condition was observed to be limiting at low light intensity?

Light availability Signup and view all the answers

What can be inferred about closely related species according to Darwin's hypothesis?

They tend to occupy different habitats to reduce competition. Signup and view all the answers

How does a population's growth relate to the most limiting resource according to Liebig’s law?

Growth is ultimately restricted by the most limiting resource. Signup and view all the answers

What does the variable $K$ represent in the logistic growth equation?

Carrying capacity Signup and view all the answers

How do you define the competition coefficients $eta$ and $eta$ in the context of interspecific competition?

They convert between the population sizes of competing species. Signup and view all the answers

When species 1's isocline is higher than species 2's isocline, what is the expected outcome?

Species 2 will become extinct. Signup and view all the answers

In a situation where the isoclines of two species cross and both carrying capacities (K1 and K2) are outermost points, what can be expected?

One species will persist while another goes extinct. Signup and view all the answers

What does the zero population growth isocline for species 1 indicate?

Equilibrium is reached when $N_1 = K_1 - \alpha N_2$. Signup and view all the answers

What best describes the situation of coexistence in competitive species?

Interspecific competition is weaker than intraspecific competition. Signup and view all the answers

In the given example, if rabbits require twice as much food as squirrels, how are their competition coefficients represented?

$\alpha = 0.5$ and $\beta = 2$. Signup and view all the answers

What could be the result if two species have overlapping niches but compete for two resources?

One species will dominate the other. Signup and view all the answers

What does a logistic growth model indicate when $dN/dt = 0$?

The population is experiencing zero growth. Signup and view all the answers

How would the competition coefficient $eta$ affect a species competing with another?

It determines how one species impacts the growth of the other. Signup and view all the answers

If species 1 and species 2 have different growth dynamics but a shared resource, how does their interaction typically result?

One species will usually outcompete the other. Signup and view all the answers

Which factor is crucial in determining if species can coexist when competing for resources?

Interspecific competition must be less than intraspecific competition. Signup and view all the answers

When modeling interspecific competition, why is it necessary to adjust for both species in the carrying capacity equations?

To reflect the reality of multi-species interactions. Signup and view all the answers

What happens to the populations of two species competing intensely for the same limited resource?

Their populations may decline due to limited resources. Signup and view all the answers

Study Notes

Competition in Biology

Competition occurs when individuals experience limited resources.
Competition is an interaction between two individuals that negatively impacts both.
Competition occurs when resources are limited, (e.g., food, mates, nesting sites).
Two categories of competition are intraspecific (within a species) and interspecific (between species).
Resources are anything an organism consumes/uses that increases the growth rate of a population when it becomes more available. Examples include sunlight, water, nutrients (N/P/K for plants), food, water, and space.
Non-consumable factors are not resources, for example, temperature.
Renewable resources are constantly regenerated (e.g., sunlight).
Non-renewable resources are not regenerated (e.g., space).
Renewable resources can originate from outside the ecosystem where a competitor lives.
Competition can reduce resource abundance but not the rate of resupply.
Resources do not respond to the rate of consumption.
Examples of renewable resources are dead leaves falling into a stream, and the nitrogen cycle in terrestrial systems.
Sometimes, the supply rate of a renewable resource generated within an ecosystem is indirectly affected by competitors.
Liebig's law of the minimum states that a population's increase is limited by the scarcest resource relative to demand.
Although consumers reduce resource abundance, not all resources limit consumer populations.
If we know the minimum amount of resource required for a population to grow we can predict the best competitor.
Examples are diatoms and silica.
Synedra can persist with lower amounts of silica, outcompeting Asterionella.
When two species compete for a single limiting resource, the species that can persist at the lowest resource level will win.
Liebig's law assumes each resource has an independent effect on population growth, but this is not always the case in nature.
At low light intensity, light is limiting, but at high intensity, nutrients are limiting.
Species limited by the same resource cannot coexist; one will persist, the other will die. This is the competitive exclusion principle.
Darwin hypothesized that competition is most intense between closely related species as they share similar traits and consume similar resources. Closely related species often occupy different habitats.
The hypothesis is that closely related species compete for the same resource, natural selection favors differences in habitat use, so a competitive advantage is preferred in a specific habitat while a disadvantage is experienced in a competitor's habitat.
A first test of this hypothesis was performed by Arthur Tansley in 1917.
Competition can also occur between distantly related species if they consume a common resource.
Examples are desert ants and rodents.
The theory of competition is an extension of the logistic growth model.
Several equations model competition for a single resource and interspecific competition.
Competition coefficients are needed in the equations of population growth to predict these interactions.
Competition can occur through exploitation, interference, or apparent competition.
Exploitation competition is when individuals consume a resource driving its abundance down to the point where other individuals cannot persist. This is an indirect interaction.
Interference competition is when competitors defend a resource but do not immediately consume it. This is a direct interaction.
Apparent competition is when species appear to compete for a resource but limit each other due to some other mechanism.
Competition among species can influence the outcome of competition.
Abiotic conditions such as availability of water, nutrients, light, and temperature can alter outcomes of competitions.
Disturbances such as frequent low-intensity fires can change community compositions.
Herbivores or predators have a trade-off between competitive ability and avoidance of predators/herbivores that influence the outcome of competitions.
Two types of competition between organisms are allelopathy and apparent competition. Allelopathy occurs when organisms release chemicals to inhibit the growth of competitors. Apparent competition occurs between species when a parasite/predator negatively affects species that share a resource.

Additional Concepts

Competition for multiple resources: organisms often compete for more than one resource, creating overlapping niches.
Coexistence: Two ways to see coexistence are when isoclines cross or when interspecific competition is weaker than intraspecific competition.

Concept Checks

What does the competitive exclusion principle predict about the outcome of two species competing for the same resource?
Which likely has a stronger impact on population abundance/growth, intraspecific competition or interspecific competition? Why?
How can abiotic conditions alter the outcome of competition?
What is the underlying trade-off that allows predators and herbivores to reverse the outcome of competition?
In the competition equations of population growth, why do we need to include competition coefficients?
Under what conditions do we predict stable coexistence of two species competing for two resources?
How is interference a form of competition?
Why is allelopathy considered a form of interference competition?

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Description

Explore the fascinating dynamics of competition within biology. This quiz covers the types of competition, the impact of limited resources, and how various resources affect population growth. Test your understanding of intraspecific and interspecific interactions.