POPULATION ECOLOGY

Question 1

What is population ecology?

Answer 1

Population ecology analyzes the factors which affect population size and how any why it changes through time

Question 2

What are the 2 important characteristics of any population?

Answer 2

1. Density
2. Dispersion of individuals

Question 3

What is density?

Answer 3

Density is the number of individuals per unit area or volume

Question 4

What types of sampling techniques can be used to estimate densities and total population sizes?

Answer 4

1. Extrapolation from small samples
2. An index of population size (e.g. bird nests, tracks, fecal droppings)
3. Mark-recapture method

Question 5

What is dispersion?

Answer 5

Dispersion is the pattern of spacing among individuals within the boundaries of a population

Question 6

What is the formula for the mark-recapture method?

Answer 6

Question 7

What are the 3 basic patterns of dispersion?

Answer 7

1. Clumped - individuals aggregate in patches
2. Uniform - individuals are evenly spaced due to direct social interactions
3. Random - position of individuals is independent of others

Question 8

Which is the most common pattern of dispersion?

Answer 8

Clumped

Question 9

What is the most rare pattern of dispersion?

Answer 9

Random

Question 10

What are demographics?

Answer 10

Demographics is the study of factors which affect the growth and decline of populations

Question 11

What is a life-table?

Answer 11

A life-table is an age-specific summary of the survival patterns of a population

Question 12

What is a survivorship curve?

Answer 12

A survivorship curve is a physical representation of a life-table, plotting individual numbers by their percent maximum lifespan

Question 13

What is a type I survivorship curve?

Answer 13

Type I shows low death rates early in life; few offspring with a long parenting period; long life span; death rate increases with age (e.g. humans)

Question 14

What is a type II survivorship curve?

Answer 14

Type II shows constant mortality, death rate constant with age (e.g. squirrels)

Question 15

What is a type III survivorship curve?

Answer 15

Type III shows a high death rate early in life; many offspring with no parenting; short life span; death rate decreases with age (e.g. clams)

Question 16

What is semelparity?

Answer 16

Semelparity are organisms which undergo a “one shot” pattern of ‘big bang’ reproduction, where a large number of offspring are produced and then die

Question 17

When is semelparity favored?

Answer 17

Where survival rate is low for offspring

Question 18

What is iteroparity?

Answer 18

Iteroparity are organisms which produce fewer offspring, but reproduce regularly

Question 19

When is iteroparity favored?

Answer 19

In more stable environments

Question 20

What kind of population growth does the exponential model of growth describe?

Answer 20

Idealized population in an unlimited environment

Question 21

What is the formula for change in population size?

Answer 21

r = B - D

When r < 0, population is shrinking

When r > 0, population is growing

Question 22

What is the formula for the exponential growth model?

Answer 22

dN/dt = B - D = rN

Question 23

What is the shape of the exponential growth model?

Answer 23

J-shaped curve

Question 24

What does the J-shaped curve for exponential growth characterize?

Answer 24

Recovering populations

Question 25

Wha kind of population growth does the logistical model describe?

Answer 25

Resources are typically limited, so population growth is therefore limited by carrying capacity (K)

Question 26

What is carrying capacity (K)?

Answer 26

Carrying capacity (K) is the maximum stable population size a particular environment can sustain without damage to the environment

Question 27

What is the formula for the logistical growth model?

Answer 27

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

Question 28

What is the shape of the logistical growth model?

Answer 28

S-shaped curve

Question 29

What does the logistic growth equation show?

Answer 29

That growth rate decreases as population size approaches carrying capacity because individuals are having to share resources

Question 30

What are density-dependent populations?

Answer 30

Density-dependent populations change population density with birth rates and death rates

Death rates increase with population density whereas birth rates decrease with population density

Question 31

What are density-independent populations?

Answer 31

Density-independent populations don’t experience a change in population density with birth and death rates

Question 32

What are density-dependent factors?

Answer 32

Density-dependent factors increase their effects on a population as population density increases

Question 33

What are density-independent factors?

Answer 33

Density-independent factors are unrelated to population density, and there is no feedback to slow population growth

Question 34

How do you estimate the time for doubling in population size?

Answer 34

Divide the number 70 by the percent for annual population growth

Question 35

The carrying capacity of Earth is hard to estimate, so what concept is used?

Answer 35

Ecological footprints (EFs) which summarize aggregate land and water area required by each person/city/nation to produce all the resources it consumes and to absorb all the waste it generates

Question 36

What are population pyramids useful for?

Answer 36

Population pyramids are useful indicators of the current state of a population structre and are a useful tool for planning, developing, or the delivery of goods and services