Changing population

Question 1

What Limits A Population?

Answer 1

Density-Dependent and Density-Independent Factors

Question 2

What is Density-Dependent?

Answer 2

factors that affect population size In Relation to population density

Question 3

what is Density-Independent

Answer 3

factor that affect population size Regardless of population density

Question 4

What are the Density Independent Factors?

Answer 4

• natural disasters
• pollutants
• extreme temperatures
• events in which the population size doesn’t matter

Question 5

What are the Negative Density dependence Factors?

Answer 5

mostly happens in Big population
- Disease
- Competition (food, shelter, space)
- more individuals = not enough resources

Question 6

What is Law of Constant Final Yield?

Answer 6

No matter how many seeds were sown, the final amount of biomass was the same because
- resources are limited
- increasing amount of seeds doesn’t increase the biomass of plants because they are overcrowded causing their biomass to level off instead

Question 7

What are the Positive Density Dependence

Answer 7

happens in tiny population
Causes Allele effect

Question 8

What is Allele effect?

Answer 8

increase ease of finding a mate, sex rations, reduced inbreeding
- lacks genetic diversity
- when the allele effect ease, rapid growth is seen

Question 9

In graph, Positive Density Dependence would

Answer 9

Increase Breeding pairs = Increase in Population Growth

Question 10

In graph, Negative Density Dependence would

Answer 10

Increase resource competition = Decrease population growth

Question 11

What do methods depend on to quantify population size?

Answer 11

• type of organism
• density of organism
• their environment

Question 12

What is Sub-sampling?

Answer 12

To estimate abundance over large areas
- uses Quadrats and transects
- typically used for sessile (doesn’t move) organism

Question 13

What is Mark-Recapture?

Answer 13

Organism is captured -> mark -> releases in habitat -> repeat and look how many are marked
M/N = R/C

Question 14

What is carrying capacity (K)

Answer 14

• result of Negative density-dependent factors
• no set of numbers which means it depends on the quality of the environment which would eventually level off

Question 15

This equation (1 - (N/K)) in Logistic Growth Model mean

Answer 15

• decline in growth rate as population approaches K

Question 16

This equation (1 - (N/K)): when population is Small

Answer 16

• N/K ~ 0, term in bracket ~ 1
• would grow rapidly as its exponential, not near the carrying capacity

Question 17

This equation (1 - (N/K)): when population is Large

Answer 17

• N/K ~ 1, term in brackets ~ 0
• growth rate approaches 0 so population is slowing down

Question 18

What is Inflection point in Carrying Capacity?

Answer 18

The point of fastest growth after which growth begins to slow

Question 19

What is Overshoot?

Answer 19

population grows beyond carrying capacity
- may occur if habitat carrying capacity decreases

Question 20

What happens when a population overshoot?

Answer 20

when population is still growing but carrying capacity is depleting then it would overshoot
followed by Die-Off (when a massive crash in pop’n)

Question 21

What is Population Cycle?

Answer 21

population would go up and down, repeat overshoot and die-off (due to availability to resources and carrying capacity)

Question 22

What is Delayed Density Dependence?

Answer 22

Delayed b/w environmental change and the time population reproduces
- population is not as responsive so population growth delays
- uses population in THE PAST instead of using the population in the present

Question 23

Size of Oscillations depends on what factors?

Answer 23

• magnitude of time delay [ increase time, decrease in responsiveness which means more likely to overshoot]
• growth rate [ grow rapidly, capacity drops (leads to overshoot as they can’t control pop’n growth) ]

Question 24

What is No Oscillations?

Answer 24

population size is easily reached

Question 25

What is Dampened Oscillation?

Answer 25

population size is mid range, delay, grows quickly and eventually find carrying capacity (level off)

Question 26

What is Stable Limit Cycle?

Answer 26

population size is continuous cycle

Question 27

Energy reserves can cause oscillations because?

Answer 27

they can cushion themselves against carrying capacity

Question 28

High-Energy stores means?

Answer 28

• energy stores keep growing
• overshot and no more reserves

Question 29

Low-Energy stores means?

Answer 29

population grows quickly, overshot (a little bit) and stay near carrying capacity

Question 30

Small population also have high risk of extinction because?

Answer 30

of Demographic stochasticity: random variation in birth and death rates
and of Environmental stochasticity; such as changing in weather

Question 31

Positive Density Dependent factors cause small population to grow quickly only when?

Answer 31

all individuals have equal birth rate and likelihood of dying based on Deterministic model
- so small population have higher extinction probability in Short Term