Unit 3 Lecture 18

Question 1

What is population ecology?

Answer 1

How population sizes change over time and space
- immigration move into populations and emigration move out of populations

Question 2

What are two major goals of population growth?

Answer 2

1. Use math to describe the dynamics of population change
2. Use this to try to predict what will happen to populations

Question 3

Recall, population growth rate is a proxy for _____ but also sets up pressure for ____

Answer 3

fitness; selection

Question 4

One should assume that if a population is growing then that population is what?

Answer 4

More fit

Question 5

Population growth also sets up pressure for selection because overtime what happens?

Answer 5

The fitness is going to start to level off because we are going to reach the carrying capacity of the population, there’s going to be more competition for resources

Question 6

What does life tables represent?

Answer 6

Summary of survival and reproduction across lifetime

Question 7

Explain how tables can be different across populations across time

Answer 7

Different populations will have different survivorship curves and different data in their table, even in the same species, sometimes depends on the months they were born

Question 8

Name the 3 different types of survivorship curves

Answer 8

• Type I: lots of offspring live to old age, up until old age where then it decreases
• Type II: Constant death rate across age
• Type III: Lots of offspring die young (few individuals survive very early on, but then when you increase to a certain age, survivorship will increase for some individuals and will live to old one)

Question 9

US human population has what type of survivorship curve?

Answer 9

Type I Survivorship

Question 10

What kind of life history strategy would you expect to see in populations with type III survivorship curve?

Answer 10

Make lots of small offspring, forgo parental offspring
- Type I curve seen when there is little predation, most mortality due to old age
- Type III curve often seen when there is lots of predation

Question 11

Give an example for each type of survivorship
curve

Answer 11

• Type I: Call mountain sheep survive to old age
• Type II: song thrushes have about the same chance of survival at any age
• Type III: Cleome droserifolia seeds, only 39 survive to produce 1 year old plants

Question 12

How do you calculation population still living next year?

Answer 12

Starting population x survival rate

Question 13

How do you calculate population of newborns next year for age 0? for rest of the ages?

Answer 13

(Number still living x Fecundity) + (Number living the following year x fecundity)

Same number as still living next year

Question 14

How do you calculate total population

Answer 14

add up all of the total populations

Question 15

What is the equation for population growth rate?

Answer 15

Nt+1 / Nt = λ (lambda)
- Nt+1 : number of individuals in time T+1 (starting population size)
- Nt: Number of individuals in time T (total population next year)

Question 16

What can we use lambda for?

Answer 16

To estimate what population size at time T+1 (future) is equal to lambda x original population size
Nt+1 = λNt

Question 17

True or False
If age specific survival rate and fecundity stays constant, the population will grow at the same rate no matter the age structure of the population

Answer 17

False

Question 18

What is stable age distribution

Answer 18

If survival and fecundity stay the same, the population will reach a predictable age distribution
- Does not mean the overall population size isn’t growing, it means that the proportion of individuals in each age class will remain the same

Question 19

Once population reach stable age distribution, growth rate becomes _____

Answer 19

Constant
- Growth rate >1 population is still growing
- Growth rate = 1 population is not changing
- Growth rate < 1 population is declining