Lecture 9 - RH

Question 1

How does the mark-recapture method work?

Answer 1

Capture sample of animals, mark them, release them

Capture another sample later and observe proportion that are marked

Extrapolate to an estimate of the total population size

Question 2

What is the formula for the mark-recapture method?

Answer 2

Animals marked in 1st sample / total population size

=

Marked animals caught in second sample / total caught in second sample

Question 3

What are the assumptions for the mark-recapture method?

Answer 3

Marked and unmarked animals are captured randomly

Marked and unmarked animals have the same mortality rate

Marked animals are neither lost nor overlooked

Question 4

What are some other limitations of the mark-recapture method?

Answer 4

“area” boundary is not easy to define

Estimating density in mobile animals is complicated by home ranges overlapping trapping area.

Question 5

How can death, birth and migration patterns be examined using the mark-recapture method?

Answer 5

Counting can be performed multiple times.

Question 6

What does the rate of growth of a population depend on?

Answer 6

Age structure and fertility

Question 7

How do births and deaths vary with age?

Answer 7

Most females give birth in a certain age range

Most deaths occur at a certain age range

These ranges vary among species

Question 8

What is survivorship?

Answer 8

Percentage of the cohort that is still alive after a set time

Question 9

What is the mortality rate?

Answer 9

A probability of dying in each year

Question 10

What is fecundity?

Answer 10

Offspring per female each year

Question 11

What is the difference between an opportunistic and equilibrium life strategy?

Answer 11

Opportunistic organisms reproduce while young and live short lives and produce many small offspring. (eg. flies)

Equillibrium organisms live long lives with large body sizes and reproduce at older ages with parents taking care of young. (eg. mammals)

Question 12

What kind of dynamics do populations of opportunistic and equilibrium species follow?

Answer 12

Equilibrium species have very stable and consistent population density

Opportunistic species densities fluctuate with conditions

Question 13

What is a population viability analysis?

Answer 13

Analysis of whether a population is viable or threatened

Question 14

What is causing the decline of Eastern Barred Bandicoot?

Answer 14

Habitat loss from clearing of 99% of native vegetation

Predation by foxes cats and dogs

Altered by fire regimes

Rabbit traps

Road kills

Question 15

What is the carrying capacity of a population?

Answer 15

The maximum size of a population that can be sustained

Question 16

What can population viability analysis tell us about a population?

Answer 16

The probability that a population will go extinct in the near future.

Question 17

What is the general formula for population growth rate?

Answer 17

dN/dt = rN

Question 18

What is rmax?

Answer 18

The maximal population growth rate intrinsic to a population

Question 19

What limits exponential growth of populations?

Answer 19

Density dependent factors such as intra and inter - specific competition for resources

Density independent factors such as natural or unnatural events

Question 20

What does the “self-thinning” rule assert?

Answer 20

The more plants that are there the lighter individual plants become

Question 21

What is K in the second population growth model?

Answer 21

The carrying capacity and the y intercept on the r vs N graph

Question 22

What is the growth model that takes into account the carrying capacity of a population?

Answer 22

dN/dt = rmax (1 - N/K)N

Question 23

What happens to an invertebrate population’s growth graph?

Answer 23

It overshoots past the carrying capacity and oscillates

Question 24

What is the time-lag model?

Answer 24

model in which the birth rate depends on density in previous generation

Question 25

Is the carrying capacity a constant?

Answer 25

Not necessarily. Can crash such as in animals that consume all the available resources

Question 26

What is the difference between r-selected strategies and k-selected strategies?

Answer 26

r-selected strategies involve opportunistic species. They have been naturally selected to depend on high population growth rates to survive.

K-selected growth rates are seen in equilibrium species which try to maintain themselves at a good population number

Question 27

What does fishing do to fish populations?

Answer 27

It destabilizes them causing risk of extinction

Question 28

What are the hypotheses regarding the reason for fluctuating fish populations following fishing? Which hypothesis has matched field data better?

Answer 28

1. Variable fishing pressure having a direct effect on fish numbers (no evidence for this hypothesis)
2. Age truncation reduces number of older individuals and young are too vulnerable
3. Age truncation changes demographic parameters such as (intrinsic growth rate)

hypothesis 3 matched field data most adequately