Population Ecology I

Question 1

What is a population?

Answer 1

group of individuals of a single species living in the same general area

Question 2

What is population ecology?

Answer 2

the study of population sin relation to environment, including environmental influences on density and distribution, age structure, and population size.

Question 3

What is population size and density & what are they influenced by?

Answer 3

Population Size: # of individuals
Population Density: the # of individuals per unit are or volume
Both are influenced by births, deaths, immigration, and emigration

Question 4

What is demography?

Answer 4

the study of the vital statistics of populations and how they change over time

Question 5

What are life tables?

Answer 5

age-specific summaries of the survival patterns of populations, summarize some of the vital statistics

Question 6

How are life tables built?

Answer 6

Determining the number of individuals that die in each age-group and by calculating the proportion of individuals surviving from one age class to the next

Question 7

What is survivorship?

Answer 7

proportion of newborns (age = 0) surviving to age (x)

Question 8

What is mortality or death rates?

Answer 8

proportion of individuals of age (x) dying by age (x+1)

Question 9

What is survival rate?

Answer 9

proportion of individuals alive at age (x) surviving to age (x+1)

Question 10

What can age structure do?

Answer 10

The relative number of individuals at each in the population predicts a population’s growth trends and can illuminate social conditions
(AP HuG Charts of different countries)

Question 11

What are two key factors that determine changes in population size (w/o immigration or emigration)?

Answer 11

Survivorship and reproductive rates

Question 12

What is a survivorship curve?

Answer 12

Age against log survivorship, is a graphic way of representing the data in a life table
* relative constant rate of death

Question 13

What are the different types of survivorship curves?

Answer 13

Type I: Parental care, few offspring, territoriality, large body size (humans)
Type II: Some parental care, more offspring, smaller body size (Muskrat)
Type III: No parental care, many offspring, very small body size (Mulleks)

Question 14

What is tracked for reproductive rates?

Answer 14

Only females, key parameters are number of breeding females and age of reproductive females

Question 15

What is a reproductive table?

Answer 15

age-specific summary of the reproductive rates in a population. Reproductive tables vary between populating and species

Question 16

What was Thomas Malthus Theory?

Answer 16

Population growth will always outrun the food supply, and there will be a point of crisis

Question 17

How to calculate the change in population size?

Answer 17

Change in population size = Births + immigrants entering population - Deaths - Emigrants leaving population

Question 18

How to calculate the per capita increase if immigration and emigration is ignored?

Answer 18

N/t = (B-D)

N= change of population size
t= time interval
B= births
D= deaths

Question 19

How can births and deaths be expressed as the average number of births and deaths pre individuals during a specific time (annual) interval?

Answer 19

B=bN
D=mN

b is the annual per capita birth rate
m is the annual per capita death rate
N is population size

Question 20

How can one rewrite the growth equation?

Answer 20

[(Delta N)/ (Delta t)] = (b-m) N

Question 21

How can the per capita rate of increase (r) be defined?

Answer 21

r= b-m
when r > 0, population grows
when r < 0, population shrink

Question 22

How can change of population size be written?

Answer 22

(Delta N)/(Delta t) = rN

Question 23

How can instantaneous growth rate be expressed?

Answer 23

(dN/dT) = r(instantaneous) N

r(instantaneous) is the instantaneous per capita rate of increase

Question 24

What is exponential population growth?

Answer 24

population increase under idealized conditions. rate of increase is at its maximum
(dN/dT) = r(max) N

Question 25

What does discrete growth mean?

Answer 25

the factor that a population increase or decrease each year by a constant proportion

Question 26

What is Lambda?

Answer 26

finite rate of increase,
Lambda = e^r
Lambda = N(t+1)/N(t)
Population grows when lambda >1
Population shrink when lambda <1

Question 27

What are some assumptions of the Exponential Model?

Answer 27

• birth and death rates are constant over time and resources are abundant
• no age or size structure, and no difference in birth and death rates among individuals
• no emigration/immigration
• no time lags (for continuous model)
• no genetic structure

Question 28

What is an issue with exponential population growth?

Answer 28

Not sustainable, eventually will outrun resources

Question 29

How to know whether to use the continuous or discrete model?

Answer 29

If there are overlapping generations, must use continuous model

Question 30

What is the equation for continuous growth?

Answer 30

N(t) = N(0) * e^rt
where t is in years

Question 31

What is equation for discrete growth?

Answer 31

N(t) = (lambda^t) * N(0)
where t is in generations

Question 32

Where might the exponential model apply?

Answer 32

apply in cases where limits to growth do not exist or have been removed, such as in the lab or an invasive species