FINAL

Question 1

Define Population

Answer 1

A group of individuals, within the same species, living in a particular space at a particular time.

Individuals in a population have the potential to interbreed.

Question 2

How do births, deaths, emigration, and imigration affect population growth through time?

Answer 2

Births and Immigration are inflow, and represent positive growth factors.

Deaths and Emigration are outflow, and represent negative growth factors.

Question 3

What controls the growth of a closed population?

Answer 3

Nt+1 = Nt + Bt - Dt

Nt = initial population size.
Bt = births in a given time.
Dt = deaths in a given time.
Nt +1 = population size after the given time has passed.

Question 4

How does one calculate the intrinsic rate of population growth (r)?

Answer 4

r = (b - d)

r = intrinsic rate of population growth.
b = birth rate = # births / population size.
d = death rate = # deaths / population size.

Question 5

What is the equation for the exponential population growth? (from memory)

Answer 5

dN/dt = r N

r = (b - d) = intrinsic rate of growth
N = population size

Question 6

How does the rate of population growth (dN/dt) change with population size (N) in the equation for exponential growth?

Answer 6

Rate of population increase goes up with N

Question 7

What does a negative intrinsic growth rate tell us about per capita birth and death rates?

Answer 7

The per capita death rate is greater than the per capita birth rate.

Question 8

What does a positive intrinsic growth rate tell us about per capita birth and death rates?

Answer 8

The per capita birth rate is greater than the per capita death rate.

Question 9

What is the difference between density-dependent vs density-independent birth and death rates?

Answer 9

• Density Dependent birth / death rates are an example of negative feed back that regulates population growth. Contributing factors include resource competition, predation, disease, and intrinsic social factors.
• Density Independent: exponential growth.

Question 10

What is the logistic growth equation for populations? What do the components mean? (from memory)

Answer 10

Occurs when population growth of a species is resource limited.

dN/dt = r N (K-N)/K

K = carrying capacity
N appraches K

Question 11

What is the role of carry capacity (K) in the logistic growth equation?

Answer 11

K is a hypothetical limit to N (population size) that an enviornment can hold.

Question 12

What happens to population growth rate (dN/dt) when the population size (N) is greater than or less than the carrying capacity (K)?

Answer 12

If N is greater than K then the growth rate will be negative.
If N is less than K then the growth rate will be positive.

Question 13

What forms of competition does the Lotka-Voltera population growth model include?

Answer 13

dN1/dt = r1 N1 (K - N1 - aN2) / K

r1 = intrinsic rate of growth of species 1
N1 = population size of species 1
N2 = population size of species 2
a = the competitive effect of species 2 on species 1 (ranges from 0 - 1)

Question 14

What is an ecological community?

Answer 14

A set of co-occuring species in a given time and place.

Question 15

What 3 broad processes control the presense or absense of species at any given location relative to the 2 million possible species on Earth?

Answer 15

Historical Filter:
- Evolved in a different region, diver dispersed to the site.

Physiological Filter:
- Can it grow and reproduce?

Biotic Filter:
- Does is successfully compete or avoid competition, can it defend itself, is it resistant to disease, etc…

Question 16

What is a Central Aim of Community Ecology?

Answer 16

To quantify how communities are structured / organized by indicating how species interact with one another.

Question 17

What is the difference between species richness, evenness, and diversity?

Answer 17

Richness:
- total number of species in a community
Evenness:
- relative abundance of species in a community.
Diversity:
- total number of speceis and their relative abunfance; combination of Richness and Evenness.

Question 18

What is the ultimate source of energy use to sustain growth of an ecological community?

Answer 18

The Sun.

Question 19

What are trophic levels?

Answer 19

The position of an organism on the food chain (web).

Question 20

Why is there more total biomass in lower trophic levels than higher trophic levels?

Answer 20

Due to a loss of energy moving up the trophic levels via heat energy and kinetic energy.

Question 21

What is the difference between bottom-up and top-down controls on community structure?

Answer 21

Bottom up:
When community structure is largely based on primary producers that start the flow of energy through a community.

Top down:
Higher trophic levels having an impact on community structure.

Question 22

Can the behavior of predators influence the diversity of primary producers within a community?

Answer 22

Yes, indirectly.

Question 23

Is predation affecting primary production a direct or indirect interaction?

Answer 23

Indirect interaction.

Question 24

What is meant by the phrase Trophic Cascade?

Answer 24

Example:
Sea otters have a large impact on sea urchins, which, in turn, have a large impact on the kelp.

Question 25

What is a keystone species?

Answer 25

A species that has disproportionatly large effect on the community relative to its biomass.

Can have large impacts on dominant competitor or prey species.

Question 26

What is an Ecosystem?

Answer 26

Defined by all the organisms and abiotic components that those organisms interact with.

Question 27

What is a Central Aim of Ecosystem Ecology?

Answer 27

To understand the factors that regulate the pools and fluzes of matter and energy through an ecological system.

Question 28

What are some of the major materials (elements) of life?

Answer 28

In order:
H, O, C, N, Ca, P, S, Na, K, Cl…

Question 29

Which of the following major elements Ca, N, P, S are derived from weathered rock?

Answer 29

Ca, P, S are derived from weathered rock.

Question 30

Which elements come from the atmosphere?

Answer 30

Nitrogen

Question 31

What are the two major ways in which predators can influence Plant Community Composition and overall Ecosystem Frunction?

Answer 31

1. Predators can eat the primary consumers, which in turn will lower the impact primary consumers have on the plant community composition.
2. Predators can alter the behavior of the primary consumers through their hunting strategies.

Question 32

What was the major conclusions of the research by Oswald Schmitz entitled “Effects of Predator Hunting Mode on Grassland Ecosystem Function”?

Answer 32

The hunting strategies of the predators (spiders) had an impact on the primary producers relative abundance and eveness, due to changing behavior in the primary consumers.

Question 33

In general, what is the observed relationship between biodversity and annual net primary productivity?

Answer 33

Increased biodiversity means increased net primary productivity.

Question 34

What is a species Niche?

Answer 34

Includes all biotic and abiotic factors required for growth and reproduction including how a species impacts its’ surroundings.

Question 35

What does the phrase Niches complementarity mean?

Answer 35

Complimentary resource use, less competition over a shared resources.

Question 36

Hwo does niche complementarity relate to the observed positive relationship between biodiveristy and net primary productivitiy?

Answer 36

Greater biodiversity means less individutal competing for the same resources and same spaces. This will lead to greater biomass per unit area and greater net primary productivity.