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Questions and Answers
What is the focus of community ecology?
What is the focus of community ecology?
- The investigation of evolutionary relationships between species.
- The analysis of global climate patterns and their impact on ecosystems.
- The examination of patterns and processes within communities of interacting species. (correct)
- The study of individual organisms and their behaviors.
How do species interactions primarily influence biological communities?
How do species interactions primarily influence biological communities?
- By influencing species survival, reproduction, and population dynamics. (correct)
- By establishing long-term climate patterns.
- By dictating the physical structure of the habitat.
- By determining the rate of nutrient cycling in the ecosystem.
Which outcome is characteristic of competition between two species?
Which outcome is characteristic of competition between two species?
- Both species are negatively affected. (correct)
- One species benefits, while the other is unaffected.
- One species benefits, while the other is harmed.
- Both species experience increased population growth.
What differentiates intraspecific competition from interspecific competition?
What differentiates intraspecific competition from interspecific competition?
How do interactions with other species impact a species' niche?
How do interactions with other species impact a species' niche?
Which factor is accounted for when comparing the realized niche to the fundamental niche?
Which factor is accounted for when comparing the realized niche to the fundamental niche?
What is the primary conclusion drawn from Connell's experiment with barnacles?
What is the primary conclusion drawn from Connell's experiment with barnacles?
In the Lotka-Volterra competition models, what does the term 'K' represent?
In the Lotka-Volterra competition models, what does the term 'K' represent?
What does the competitive exclusion principle state?
What does the competitive exclusion principle state?
How does niche partitioning allow species to coexist?
How does niche partitioning allow species to coexist?
What does the term 'alpha' ($\alpha$) represent in the Lotka-Volterra competition model?
What does the term 'alpha' ($\alpha$) represent in the Lotka-Volterra competition model?
Why is understanding species interactions important in community ecology?
Why is understanding species interactions important in community ecology?
What is the ecological definition of a 'community'?
What is the ecological definition of a 'community'?
What does it mean if the competition coefficient (alpha or beta) is equal to 1?
What does it mean if the competition coefficient (alpha or beta) is equal to 1?
How does biodiversity relate to natural selection and species interactions?
How does biodiversity relate to natural selection and species interactions?
What is a 'niche' in ecological terms?
What is a 'niche' in ecological terms?
In the context of species interactions, what does '0' typically represent as an effect on a species?
In the context of species interactions, what does '0' typically represent as an effect on a species?
What conditions must be met for two species to coexist, according to isocline analysis?
What conditions must be met for two species to coexist, according to isocline analysis?
What is indicated when a population's size (N) is equal to its carrying capacity (K)?
What is indicated when a population's size (N) is equal to its carrying capacity (K)?
How is the fundamental niche of a species defined?
How is the fundamental niche of a species defined?
What is a zero-growth isocline in the context of population ecology?
What is a zero-growth isocline in the context of population ecology?
According to the Lotka-Volterra competition models, If $\alpha$ is 0, what does this imply?
According to the Lotka-Volterra competition models, If $\alpha$ is 0, what does this imply?
The Lotka-Volterra equations are used for what purpose?
The Lotka-Volterra equations are used for what purpose?
If $\alpha > 1$, what does this say about interspecific competition?
If $\alpha > 1$, what does this say about interspecific competition?
Imagine a scenario where two species are competing for the same resources. After sometime, it is observed that Species A is thriving while Species B is on the verge of extinction. Which outcome of competition is this?
Imagine a scenario where two species are competing for the same resources. After sometime, it is observed that Species A is thriving while Species B is on the verge of extinction. Which outcome of competition is this?
Species A benefits from an environment but has no effect on Species B. What type of species interaction is this?
Species A benefits from an environment but has no effect on Species B. What type of species interaction is this?
In population ecology, what generally causes a transition from exponential to logistic growth?
In population ecology, what generally causes a transition from exponential to logistic growth?
What is the formula for the zero growth isocline of a competition equation for Species 1 to which pop size (N) is zero?
What is the formula for the zero growth isocline of a competition equation for Species 1 to which pop size (N) is zero?
What is the formula for the zero growth isocline of a competition equation for Species 1 to which alpha ($\alpha$) is zero?
What is the formula for the zero growth isocline of a competition equation for Species 1 to which alpha ($\alpha$) is zero?
What do competition coefficients describe?
What do competition coefficients describe?
If $\alpha = 0$, what does that mean?
If $\alpha = 0$, what does that mean?
What does Exponential growth describe?
What does Exponential growth describe?
What is a key component of Logistic growth models?
What is a key component of Logistic growth models?
What does INTRAspecific competition describe?
What does INTRAspecific competition describe?
If $\beta = 1$:
If $\beta = 1$:
The outcome is a stable equilibrium, and the end result is:
The outcome is a stable equilibrium, and the end result is:
Which of the following describes the outcome of Competition?
Which of the following describes the outcome of Competition?
Flashcards
Ecological Communities
Ecological Communities
Groups of populations of different species interacting within a given area.
Community Ecology
Community Ecology
The study of patterns and processes within ecological communities.
Species Interactions
Species Interactions
Interactions between species that influence survival, reproduction, and population dynamics.
Competition
Competition
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INTRAspecific competition
INTRAspecific competition
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INTERspecific competition
INTERspecific competition
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Niche
Niche
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Competitive Exclusion Principle
Competitive Exclusion Principle
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Competitive exclusion
Competitive exclusion
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Niche partitioning
Niche partitioning
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Fundamental niche
Fundamental niche
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Realized niche
Realized niche
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Lotka-Volterra Equations
Lotka-Volterra Equations
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Exponential growth
Exponential growth
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r
r
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Logistic Model
Logistic Model
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Carrying capacity (K)
Carrying capacity (K)
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Competition coefficients
Competition coefficients
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Alpha (α)
Alpha (α)
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Beta (β)
Beta (β)
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Zero-Growth Isocline
Zero-Growth Isocline
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Study Notes
- Communities consist of different species populations in a given area.
- Community ecology studies the patterns and processes within these communities.
Species Interactions
- Species interactions influence survival and reproduction, as well as population dynamics.
- Species interactions act as agents of natural selection and drive biodiversity.
Types of Species Interactions
- Competition has a negative effect on both species involved (-/-).
- Antagonism (predation, parasitism) has a positive effect on one species and a negative effect on the other (+/-).
- Mutualism has a positive effect on both species (+/+).
- Commensalism has a positive effect on one species and no effect on the other (+/0).
- Amensalism has a negative effect on one species and no effect on the other (-/0).
Types of Competition
- Intraspecific competition occurs between individuals of the same species.
- Interspecific competition occurs between individuals of different species.
Niche Concept
- Niche refers to the range of environmental conditions a species needs to survive and reproduce.
- Interactions with other species can alter a species' niche.
Competitive Exclusion Principle
- The competitive exclusion principle states that two or more species using the exact same niche cannot coexist.
- Niche partitioning allows species to share resources.
Fundamental vs. Realized Niche
- Fundamental niche: The complete range of conditions under which an organism could theoretically exist.
- Realized niche: The portion of the fundamental niche a species actually occupies, considering interactions with other species.
Connell's Barnacle Experiment
- Joseph Connell performed an experiment with Balanus and Chthamalus barnacles.
- When Chthamalus was removed, Balanus did not invade (limited by dessication).
- When Balanus was removed, Chthamalus was able to live in the lower tidal zone (limited by competition).
Lotka-Volterra Competition Models
- Mathematical models describe species interactions and their graphical representations.
- dN1/dt = r1N1[(K1 - N1 - αN2)/K1] models species 1.
- dN2/dt = r2N2[(K2 - N2 - βN1)/K2] models species 2.
- These were independently proposed by Alfred J. Lotka in 1925 and Vito Volterra in 1926.
Exponential Growth Model
- Exponential growth is density-independent.
- dN/dt = rN represents exponential growth.
- dN/dt is the rate of population growth over time.
- r is the intrinsic growth rate (births minus deaths).
- N is the population size.
Logistic Growth Model
- Logistic models add a "brake" based on carrying capacity; growth is density-dependent.
- (K – N)/K ~ 1 when N is low relative to K.
- (K – N)/K ~ 0 when N approaches K.
- (K – N)/K is negative when N exceeds K.
Competition Coefficients
- Competition coefficients quantify how much one species negatively affects another.
- α (alpha) represents the effect of species 2 on species 1.
- β (beta) represents the effect of species 1 on species 2.
- If α = 0, species 2 has no effect on the population growth of species 1.
- If α = 1, individuals of species 2 have the same effect on species 1 as another individual from species 1.
- If 0 < α < 1, species 2 reduces the growth of species 1, but less than species 1 would inhibit itself (Intraspecific competition is greater).
- If α > 1, species 2 reduces the growth of species 1 to a greater extent than species 1 would inhibit itself (Interspecific competition is greater).
- If β = 0, species 1 has no effect on the population growth of species 2.
- If β = 1, individuals of species 1 have the same effect on species 2 as another individual from species 2.
- If 0 < β < 1, individuals of species 1 reduce the growth of species 2, but less than species 2 would inhibit itself (Intraspecific competition is greater).
- If β > 1, individuals of species 1 reduce the growth of species 2 to a greater extent than species 2 would inhibit itself (Interspecific competition is greater).
Zero Growth Isocline
- When dN/dt = 0 , and pop. size (N) = K
- A set of values for N1 and N2 at which population growth rate for the given species is zero.
- Species 1: K1 = α N2 + N1
- Species 2: K2 = β N1 + N2
Possible Outcomes of Competition
- Four possible outcomes of competition
- Outcome 1: Species 1wins
- Outcome 2: Species 2 wins
- Outcome 3: Either Species Wins
- Outcome 4: Stable coexistence
- When Species 1 is above Species 2 , Species 1 will drive the other to extinction.
- When Species 1 is below Species 2, the opposite is true.
- When the lines cross, only one will survive.
- The outcome can be coexistence, which results in a stable equilibrium
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