Ecology Flashcards: Survivorship Curves & Food Webs

Questions and Answers

What are survivorship curves?

If we plot out mortality over time, we can see the changing effects of and how this influences the population and its structure.

Which type of survivorship curve is characterized by high age-specific survival probability in early and middle life?

Type I (correct)

Type III

Type II

What causes mortality in populations?

A wide range of reasons including predation, starvation, and disease.

How is mortality linked to population structure?

Mortality may be density dependent. Signup and view all the answers

If density increases and mortality increases, it is density independent.

False Signup and view all the answers

What is the relationship between birth and death rates in populations?

Birth and death rates interact as the population changes. Signup and view all the answers

Which of the following describes r selection strategy?

Numerous young, little investment per individual Signup and view all the answers

What influences population structure between r and K strategies?

r strategy will have a population structure biased to juveniles, while K strategy will be biased to adults. Signup and view all the answers

What are limits to population growth?

Factors like overpopulation, diseases, lack of food, and predators limit population growth. Signup and view all the answers

What is meant by demographic transition?

The interaction of birth and death rates as the population changes. Signup and view all the answers

What is inverse density dependence?

A situation where population may be controlled at high densities but may be driven to extinction at low densities. Signup and view all the answers

What is competition in ecological terms?

Interactions between organisms over limited resources. Signup and view all the answers

Study Notes

Survivorship Curves

Survivorship curves plot mortality rates over time, illustrating population structure changes through development and aging.

Survivorship Curve Types

Type I: High survival rates in early and middle life, rapid decline in later life; common in species with few offspring and high parental care, like humans.
Type II: Intermediate mortality rates regardless of age; observed in some birds and lizards.
Type III: High mortality early in life with lower rates for those that survive; typical of species with many offspring, such as marine invertebrates (e.g., oysters).

Causes of Mortality

Mortality can arise from predation, starvation, and disease; ecological factors impact mortality linked to life history and environmental interactions.

Rates of Death

Mortality rates may be density-dependent; higher population densities can lead to increased mortality due to competition, affecting individual fecundity.

Dependent vs. Independent Mortality

Mortality is considered density-dependent if increased density corresponds with heightened mortality rates.

Birth vs. Death

Population dynamics involve interactions between reproduction and mortality rates, influencing overall population size.

Life History Strategies

Organisms adopt either r-selection (many offspring, low investment) or K-selection (few offspring, high investment), leading to different population structures and growth rates.

Population Effects

r-strategy populations tend to have a high number of juveniles, while K-strategy populations show a bias toward adults, influenced by long development times.

Limits to Population Growth

Populations cannot grow indefinitely due to factors like overpopulation, disease, and resource scarcity, concepts originating from Thomas Malthus and influencing Darwin's natural selection theory.

Demographic Transition

Interaction between birth and death rates alters as populations evolve over time.

Inverse Density Dependence

At low densities, certain populations may face extinction despite high mortality at higher densities; important for the conservation of rare species like flamingos.

Competition

Competition involves interactions between organisms for limited resources, affecting population dynamics and strategies for survival.

Description

Explore key concepts in ecology such as survivorship curves and their types. This flashcard set provides a clear understanding of how mortality rates influence population dynamics and interactions within food webs. Perfect for students studying environmental science or biology.