Ch 53 Population Ecology

Question 1

Density

Answer 1

The number of individuals per unit area or volume

Question 2

Dispersion

Answer 2

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

Question 3

What two factors influence the spacing of individuals in a population?

Answer 3

1) Environmental factors

2) Social factors

Question 4

In most cases, it is 1)___ and 2)___ to count all the 3)___ in a population

Answer 4

1) Impractical
2) Impossible
3) Individuals

Question 5

Sampling

Answer 5

Techniques used to estimate densities and total population sizes

Question 6

Mark-recapture method (definition)

Answer 6

A method for estimating population size by extrapolating from small samples

Question 7

Mark-recapture method (steps)

Answer 7

1) Capture, tag, and release a random sample of individuals in a population
2) Marked individuals are given time to remix into the population
3) Scientists capture a second sample of individuals and note how many of them are marked
4) Population size (N) is estimated

Question 8

Mark-recapture method (Equation)

Answer 8

N = (sn)/x

s = tagged individuals 
n = second captured sample 
x = tagged individuals in second sample

Question 9

The actual density of a population is the result of what?

Answer 9

An interplay between processes that add individuals to a population and those that remove individuals

Question 10

Process that add individuals to a population

Answer 10

1) Births

2) Immigration

Question 11

Process that removes individuals from a population

Answer 11

1) Death

2) Emigration

Question 12

Demography

Answer 12

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

Question 13

Life table

Answer 13

An age-specific summary of the survival pattern of a population

Question 14

How is a life table best made?

Answer 14

By following the fate of a cohort

Question 15

Cohort

Answer 15

A group of individuals of the same age

Question 16

Survivorship curve

Answer 16

A graphic way of representing the data in a life table

Question 17

Survivorship curve: Type I

Answer 17

Few deaths early on in life, most deaths within a small range of time later in life

Question 18

Survivorship curve: Type II

Answer 18

Relatively steady number of deaths throughout life

Question 19

Survivorship curve: Type III

Answer 19

Most deaths occur early on in life

Question 20

For species with sexual reproduction, demographers often concentrate only on ___ in a population

Answer 20

Females

Question 21

Fertility table (fertility schedule)

Answer 21

An age-specific summary of the reproductive rates in a population

Question 22

If immigration and emigration are ignored, a population’s growth rate equals 1)___ ___ minus 2)___ ___

Answer 22

1) Birth rate

2) Death rate

Question 23

A change in population size equals:

Answer 23

Birth + Immigrants - Deaths - Emigrants

Question 24

Mathematical expression for population growth

Answer 24

Births - Deaths

Question 25

Zero population growth (ZPG)

Answer 25

Occurs when the birth rate equals the death rate

Question 26

Exponential population growth

Answer 26

Population increase under idealized conditions

Question 27

Logistic population growth

Answer 27

A model where the per capita rate of increase declines as carrying capacity is reached

Question 28

Carrying capacity

Answer 28

The maximum population size

Question 29

Logistic population growth models are useful for:

Answer 29

Estimating possible growth

Question 30

Life history (definition)

Answer 30

Comprises the traits that affect its schedule of reproduction and survival

Question 31

Life history (traits)

Answer 31

1) The age at which reproduction begins 2) How often the organism reproduces 3) How many offspring are produced during each reproductive cycle

Question 32

Semelparity (Big-bang reproduction)

Answer 32

Reproduce once and die

Question 33

Iteroparity (Repeated production)

Answer 33

Produce offspring repeatedly

Question 34

What kind of environments favor semelparity?

Answer 34

High variable or unpredictable environments

Question 35

What kind of environments favor iteroparity?

Answer 35

Dependable environments

Question 36

R-selection

Answer 36

Selects for life history traits that maximize reproduction Density-independent selection

Question 37

K-selection

Answer 37

Selects for life history traits that are sensitive to population density Density-dependent selection

Question 38

Two general questions about regulation of population growth:

Answer 38

1) What environmental factors stop a population from growing indefinitely? 2) Why do some populations show radical fluctuations in size over time, while others remain stable?

Question 39

Density-dependent birth and death rates are an example of what?

Answer 39

Negative feedback that regulates population growth

Question 40

Factors that affect density-dependent birth and death rates:

Answer 40

1) Competition for resources 2) Territoriality 3) Disease 4) Predation 5) Predation 6) Toxic wastes 7) Intrinsic physiological factors

Question 41

Long-term population studies have challenged what?

Answer 41

The hypothesis that populations are relatively stable over time