Lecture 24- Population Ecology

Question 1

How is ecology defined?

Answer 1

Branch of biology that studies the interactions between living organisms and their physical environment

Question 2

How is population ecology defined?

Answer 2

Branch of ecology that studies the processes (dynamics) that affect the distribution and abundance of organism populations (study of change in populations)

Question 3

What does the formula B=bN imply about a population?

Answer 3

The expected number of births per year in a population size of N (expected number of births= per capita birth rate times population size)

Question 4

What is the intrinsic rate of increase?

Answer 4

Maximum rate at which a population could increase under ideal conditions (r max)

Question 5

Which mechanisms can increase the size of a population?

Answer 5

Birth and immigration

Question 6

What is an r-selected species?

Answer 6

Species that maximize reproduction rate and usually exhibit life history traits such as early maturity, large number of offspring, short lifespan, and little parental care

Question 7

What does the formula D=mN imply about a population?

Answer 7

Average likelihood of deaths per year in a population size of N (expected number of deaths= per capita mortality rate times population size)

Question 8

What is the shape of the curve of a logistic growth model?

Answer 8

Sigmoid (S-shaped)

Question 9

Which mechanisms can decrease the size of a population?

Answer 9

Deaths (mortality) & emigration

Question 10

What can be inferred about a population of the per capita rate of change (r) is less than 0?

Answer 10

Population is shrinking

Question 11

With regards to a logistic growth model, what can be inferred about a population is the value of N is very small?

Answer 11

Small N results in a (K-N)/K value close to 1 which implies a rapid growth rate

Question 12

What does population growth in nature not follow a perfectly logistic curve?

Answer 12

Populations tend to fluctuate around carrying capacity/ environmental changes/carrying capacity may change

Question 13

How is population density defined?

Answer 13

Population per unit area (volume in sea)

Question 14

In what type of environment would an r-selected strategy be favorable?

Answer 14

Variable/ unpredictable environments

Question 15

What can be inferred about a population if the per capita rate of change (r) is greater than zero?

Answer 15

Population increasing

Question 16

What are the two main categories of factors that influence population size?

Answer 16

Density-dependent factors & density-independent factors

Question 17

How is carrying capacity (K) defined?

Answer 17

Largest population that can be maintained for an indefinite period by a particular environment

Question 18

What can be inferred about a population if the per capita rate of change (r) is equal to zero?

Answer 18

Zero population growth (ZPG)/no net change/dynamic equilibrium

Question 19

What is iteroparity?

Answer 19

Reproductive strategy in which organisms are capable of having offspring many times over the course of their lives

Question 20

Under what conditions would a population follow an exponential growth model?

Answer 20

When every member of a population reproduces at physiological capacity (idealized and theoretical)

Question 21

With regards to a logistic growth model, what can be inferred about a population if the value of N is close to K?

Answer 21

As the value for B approaches the value for K, the value for (K-N)/K approaches zero which implies a slow population growth rate

Question 22

What are some limitations to the exponential growth model?

Answer 22

Environmental resistance/buildup of toxic wastes/limited food, resources, and living space

Question 23

What is semelparity?

Answer 23

Reproductive strategy in which an organism only reproduces once before death

Question 24

What is a k-selected species?

Answer 24

Species characterized by having only few offspring, but investing high amounts of parental care