Population Growth

Question 1

What are population dynamics?

Answer 1

changes in population size over time

Question 2

What are the 3 types of population growth?

Answer 2

• geometric (unlimited)
• exponential
• logistic

Question 3

What kind of reproduction is geometric growth?

Answer 3

discrete or pulsed reproduction

Question 4

What does λ mean in geometric growth equation?

Answer 4

finite rate of increase

Question 5

What kind of reproduction is exponential growth?

Answer 5

overlapping or continuous reproduction

Question 6

What does r mean in exponential growth equation?

Answer 6

intrinsic reproductive rate

Question 7

What is the relationship between λ and r?

Answer 7

r = lnλ
λ = e^r

Question 8

What does λ = 1 mean?

Answer 8

no change

Question 9

What does λ >1 mean?

Answer 9

population increases

Question 10

What does λ <1 mean?

Answer 10

population decreases

Question 11

What does r = 0 mean?

Answer 11

no change

Question 12

What does r > 0 mean?

Answer 12

population increases

Question 13

What does r < 0 mean?

Answer 13

population decreases

Question 14

What does maximum intrinsic growth rate ( r max) vary from?

Answer 14

about 0.001 per day for large mammals to about 1000 per day for viruses and bacteria

Question 15

How is growth compounded for λ?

Answer 15

distinct intervals

Question 16

How is growth compounded for r?

Answer 16

continuously

Question 17

What does replacement level reproduction mean?

Answer 17

just offsets deaths, so population is stable

Question 18

What do abiotic and biotic factors influence?

Answer 18

r

Question 19

What does density independent factors mean?

Answer 19

influence on r is not dependent on population size

Question 20

Are density independent factors often abiotic or biotic?

Answer 20

abiotic

Question 21

What does density dependent factors mean?

Answer 21

influence on r is dependent on population size

Question 22

Are density dependent factors often abiotic or biotic?

Answer 22

biotic (exception water)

Question 23

What does dispersal mean?

Answer 23

movement between patches

Question 24

What is local extinction?

Answer 24

elimination from a patch

Question 25

What is the formula for r in terms of metapopulation dynamics?

Answer 25

r = birth rate - death rate + immigration rate - emigration rate

Question 26

How do high immigration or emigration rates affect metapopulations?

Answer 26

keep population levels low but patches rarely stay unoccupied for long

Question 27

What do source populations enable?

Answer 27

enable sink populations to reestablish if they go extinct

Question 28

What are metapopulations?

Answer 28

set of distinct populations interconnected by dispersal corridors

Question 29

What is environmental stochasticity?

Answer 29

variation in factors that affect population growth

Question 29

What is Levins’ model?

Answer 29

change in colonized patches over time

Question 30

What is the allee effect?

Answer 30

r goes down at low population sizes (population size affects birth and death rates)

Question 31

What is the allele effect often seen in?

Answer 31

social animals because of difficulty in finding mates

Question 32

What is deterministic chaos?

Answer 32

• the “butterfly effect”
• variation so high it cannot be easily distinguished from random fluctuations

Question 33

When is deterministic chaos often seen?

Answer 33

when r is very high

Question 34

What is a population?

Answer 34

a group of organisms of the same species occupying a particular space at a particular time

Question 35

What do both the geometric and exponential growth models assume?

Answer 35

• unlimited resources
• constant birth and death rates

Question 36

What are examples of animals that do geometric growth?

Answer 36

squirrels, elk, wolves

Question 37

What are examples of exponential growth?

Answer 37

aphids, water hyacinth, bacteria

Question 38

How does per capita death rate change as population increases (logistic?)?

Answer 38

starts low, rapidly increases, then levels off

Question 39

What does the logistic growth model assume?

Answer 39

limited resources and continuous reproduction

Question 40

Why do bison populations remain below K?

Answer 40

periodic culling

Question 41

What are four assumptions of Levins’ model?

Answer 41

• all populations have a substantial and equal risk of extinction
• local population dynamics are not synchronized
• habitats are situated close enough so recolonization is possible
• suitable habitat occurs in discrete populations that may be occupied by a breeding population

Question 42

When does a non zero equilibrium patch occupancy rate occur?

Answer 42

when change in colonized patches over time (dp/dt) = 0 and colonization rate is equal to extinction rate