Chapter 53: Population Ecology Flashcards Preview

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Flashcards in Chapter 53: Population Ecology Deck (35)
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1

What is a population?

A group of individuals of the same species that occupy the same general area

2

What 4 factors influence population?

Density
Dispersion
Structure
Growth Rate

3

What is density?

The number of individuals per unit area or volume

- density is the result of an interplay between processes that add individuals to a population and those that remove individuals

4

What is dispersion?

The pattern of spacing among individuals within the boundaries of the population

5

______ and ______ affect population size.

Births; deaths

6

What are the 3 types of dispersion?

1. Clumped dispersion
2. Uniform dispersion
3. Random dispersion

7

What is clumped dispersion?

When organisms aggregate (group) in patches

- this is due to resource availability and behavior

8

What is uniform dispersion?

When organisms are evenly distributed

- this is due to social interactions such as territoriality (claiming territory)

9

What is random dispersion?

When the position of each organism is independent of other organisms

- this is due to the absence of strong attractions or repulsions

10

What is demography?

The study of vital statistics of a population and how they change over time

11

What factors affect demography?

1. Population size
2. Density and Distribution
3. Age Structure, Sex Ratio
4. Birth, Death, Immigration and Emigration

12

What is age structure?

The relative number of individuals at each age

13

What is immigration?

The influx of new individuals from other areas

14

What is emigration?

The movement of individuals out of a population

15

What is a life table?

An age specific summary of the survival pattern of a population

16

What is the best way to construct a life table?

Follow the fate of a cohort, a group of individuals of the same age.

17

What is a Type I species?

Species that invest a lot of energy into caring for their young
- have low death rates early in life

E.g., humans and large vertebrates

18

What is a Type II species?

Species that have an equal probability of dying at any age

E.g., mammals and birds

19

What is a Type III species?

Species that invest little energy raising their young
- high death rages among offspring

E.g., fish, invertebrates, plants

20

What are the 3 types of population growth models?

1. Constant Growth
2. Exponential Growth
3. Logistic Growth

21

What is constant growth?

When the population continues to grow constantly

22

What is exponential growth?

The increase of a population in an ideal, unlimited environment.

Equation:

^N/^t = rN

^N = change in population size
^t = change in time
If r>0 = increasing population
If r<0 = decreasing population
N = current population size

23

What is the intrinsic rate of increase (r)?

The rate at which the population increases

24

What is per capita rate of increase?

A population's growth rate, which equals the birth rate minus the death rate.

^N/^t = B - D

^N = change in population size
^t = change in time

25

What is expected of exponential growth?

It cannot continue on forever.

It has a 'Carrying Capacity' (K) (limit).
Either:
- the population will crash
- slower population growth

26

What is the J-shaped curve?

An exponentially growing population that is rebounding after being reduced.

27

What is logistic growth?

A population's change over time in response to feedback from the environment or its own population density. (S curve!)

Equation:

dN/dt = rN (K-N)/K

dN = rate of change in population size
dt = rate of change in time
If r>0 = increasing population
If r<0 = decreasing population
N = current population size
K = carrying capacity

28

What are density-dependent factors?

Factors that cause a change in the population size that are related to the population density.

E.g., if you have a small density of 20 birds in a large forest, their population will continue to increase because they have plenty of resources. However, if you have a large density of 6,000 birds in a smaller forest, the birds will compete for their resources and the population may start to decline.

29

What are density-independent factors?

Factors that cause a change in the population size that are unrelated to the population density.

E.g., if you have a population of 20 deer, or 50 deer, or 100 deer, and there's a fire, it doesn't matter how many deer you started with, what matters is that the population got affected regardless of how many there were.

30

The effects of density-dependent factors _________ as the population density ______.

Increases; rises