Populations III: Life Tables

These flashcards cover key concepts regarding population dynamics, life history traits, community interactions, and ecological models as presented in the lecture.

What is the density-dependent growth model?

It describes how population growth rates are influenced by population density.

What equation represents unrestricted growth?

dN/dt = rN.

Define 'Carrying Capacity' (K).

The maximum population size that the environment can sustain.

What occurs at the carrying capacity, K?

Population growth rate (r) becomes zero.

What is the intrinsic growth rate represented by in equations?

r.

How does a continuous-limited environment differ from a continuous-unlimited environment?

Continuous-limited takes into account carrying capacity, while continuous-unlimited does not.

What does the term 'logistic growth' refer to?

Population growth that initially is exponential but slows as the population reaches carrying capacity.

What impact does density-dependent competition have on population growth?

It can limit resources, decreasing growth rate as population density increases.

What is a life table?

A table that shows the survival and reproductive rates of individuals of different ages in a population.

What is meant by net reproductive rate (R0)?

The expected number of offspring produced by an average female over her lifetime.

Define 'generation time' (T).

The average period between the birth of an individual and the birth of its offspring.

What does λ represent in population studies?

The finite rate of population increase; λ > 1 means growing, λ = 1 stable, λ < 1 declining.

What is the significance of the inflection point in population growth?

It is where the rate of population growth is at its maximum.

What assumptions are made in logistic growth models?

No immigration/emigration, constant environmental conditions, no time lags, and linear relationships between birth and death rates.

What is the difference between 'r' and 'K' selection?

'r' selection prioritizes high growth rates in unstable environments, while 'K' selection focuses on stable environments near carrying capacity.

What is the role of predators in ecological systems?

They can control prey populations, affecting the structure and dynamics of communities.

Define exploitative competition.

When one species limits the availability of resources for another species.

What is interference competition?

Direct interaction between species, such as fighting or chemical warfare, influencing resource availability.

What is Gause's Competitive Exclusion Principle?

Two species competing for the same resource cannot coexist indefinitely.

What does the Lotka-Volterra model describe?

The interactions between predator and prey populations.

What are 'Zero Net Growth Isoclines' (ZNGIs)?

The resource levels at which a species neither increases nor decreases in population.

How does apparent competition differ from true competition?

It occurs when two species indirectly affect each other's population through a shared predator.

What is meant by bottom-up control in ecosystems?

When primary producers limit the population sizes of higher trophic levels.

What is a keystone species?

A species that has a disproportionate impact on its environment relative to its abundance.

What are traits of mutualisms?

Interactions where both species benefit, ranging from facultative to obligate relationships.

Define amenity value of biodiversity.

The intrinsic value that biodiversity provides in maintaining ecosystem functions.

What is the significance of interactions in community ecology?

They explain how species coexist, impact population dynamics, and affect community structure.

Explain the term 'trophic cascade.'

An ecological phenomenon triggered by the addition or removal of top predators.

What is direct effect in interspecific interactions?

When two species interact without involving intermediate species.

Describe indirect effects in ecological interactions.

When interactions between two species involve one or more intermediate species.

What are dominant species in an ecological community?

Species that are most abundant or have the highest biomass.

How do food webs differ from food chains?

Food webs depict multiple feeding relationships and energy flows, while chains depict a single linear path.

What role do microbes play in ecosystems?

They help decompose organic matter and recycle nutrients.

What is resource partitioning?

The division of limited resources by species to help avoid competition.

Explain the concept of community structure.

The composition and organization of species within an ecological community.

What effect do invasive species have on local ecosystems?

They can disrupt local species interactions and dynamics, often leading to declines of native species.

How do stable isotopes help in ecological studies?

They provide information about diet and trophic levels based on the carbon and nitrogen ratios.

What is mutualism?

A type of interaction where both species derive benefit from the relationship.

What defines a community in ecology?

An assemblage of populations of different species in a specific area that interact.

What is the role of decomposers in the ecosystem?

They break down dead organic matter, recycling nutrients back into the ecosystem.

Explain the concept of a guild in ecology.

A group of species in a community that exploit the same resources in a similar manner.

What are foundational species?

Species that have a strong role in structuring a community.

What contributes to the diversity of an ecosystem?

The variety of species and their interactions within the community.