Midterm Review

Question 1

Why are trophic chains often depicted as pyramids?

Answer 1

Trophic pyramids illustrate the transfer of energy through food chains. Producers occupy the base, with herbivores above them, then carnivores, and so on. Each level loses energy through respiration and other processes, resulting in a pyramid shape with a decreasing amount of energy available at higher levels.

Question 2

Define NPP

Answer 2

Net Primary Productivity, accumulation of energy by plants or other autotrophs

Question 3

Define GPP

Answer 3

Gross Primary Productivity, assimilation of energy (photo or chemosynthesis) by plants or other autotrophs

Question 4

What are the main factors limiting NPP in terrestrial ecosystems? What other factors are important for aquatic systems?

Answer 4

In terrestrial ecosystems:
-Light availability
-Water availability
-Nutrient availability
-Temperature
-Disturbance

In aquatic systems:
-Nutrient availability (especially nitrogen and phosphorus)
-Light availability (depth and turbidity)
-Temperature
-Dissolved oxygen levels
-Salinity (in marine systems)

Question 5

Define stoichiometric mismatch

Answer 5

Stoichiometric mismatch occurs when the relative proportions of essential elements (e.g, nitrogen and phosphorus) available in the environment differ from the needs of organisms, limiting growth and productivity

Question 6

Describe the phosphorus cycle

Answer 6

How phosphorous moves through earths various systems, has no atmospheric stage, very slow return, phosphorous gets locked into sediments and only returns with geologic activity

Question 7

Describe the carbon cycle

Answer 7

How carbon moves energy through ecosystems, photosynthesis, soil carbon, microbial respiration and decomposition, plant biomass, plant respiration, sea air gas exchange

Question 8

Describe the nitrogen cycle

Answer 8

How nitrogen moves through the biosphere, nitrogen fixation brings nitrogen into the biosphere, nitrogen then moves through ecosystems, Nitrification -aerobic transformation of ammonium, returns back to the atmosphere via denitrification

Can be found in organic decomposition, fertilizers, anammox, and eutrophication

Question 9

Describe directional selection

Answer 9

Selection favors an extreme phenotype (shifts the mean)

Question 10

Describe stabilizing selection

Answer 10

Selection against phenotypic extremes (reduces variance)

Question 11

Describe disruptive selection

Answer 11

Selection against intermediate phenotypes (increases variance)

Question 12

What effect does each of these forms of selection have on population-level trait means and variances?

Answer 12

Answered above^^

Question 13

How would you express these differences in graphical form?

Answer 13

On Notes

Question 14

Which force or forces of evolution are inherently random?

Answer 14

Mutation and Drift

Question 15

Which force or forces of evolution introduce variation to populations?

Answer 15

Mutation and Gene Flow

Question 16

Which force or forces of evolution inherently reduce variation?

Answer 16

Drift and Selection

Question 17

Which force or forces of evolution are never random?

Answer 17

Selection

Question 18

Why do the survival probabilities of male and female kestrels differ in the egg removal and addition experiment (discussed in lecture 5)?

Answer 18

There are trade-offs between current and future reproductive investment such as parental survival.

-Females invest more energy in the incubation and chick process than males.
-Removing eggs could reduce the energy demand for females, increasing their survival.
-Adding eggs increases the energy demand and reduces survival
-Must also take into account individual variation and predication

Question 19

Explain what semelparity and iteroparity are and explain what (beyond the number of reproductive events) is common among species exhibiting each of these life history traits (i.e, what do all semelparous species have in common, other than reproducing only once? What do all iteroparous species have in common, other than the ability to reproduce more than once?)

Answer 19

Iteroparity is multiple reproductive cycles over the course of a lifetime. Gradual reproductive investment, lower offspring count per event (longer lifespan), greater parental flexibility, predictable environments (e.g, humans and mammals)

Semelparity is a single reproductive event in a lifetime. Requires massive resource allocation, totally exhausts resources and results in mortality, unpredictable environments, maximizes the chance of leaving successful offspring(e.g, agave and pacific salmon)

Question 20

There is often a trade-off between offspring quantity and offspring quality. What does this mean?

Answer 20

Larger, more well provisioned offspring are more likely to survive. The more a species invests in each offspring, the fewer it can make

Smaller, less provisioned offspring are less likely to survive. However, a species invests less in each offspring, meaning it can produce more

Question 21

T/F) Sexual functions are divided among individuals in hermaphroditic species or individuals

Answer 21

False, they have both male and female reproductive organs within the same individual

Question 22

T/F) Sexual functions are divided among individuals in dioecious species or individuals

Answer 22

True, separate male and female individuals

Question 23

T/F) Sexual functions are divided among individuals in monoecious species or individuals

Answer 23

True, separate male and female flowers on the same individual

Question 24

Explain Bateman’s Principal

Answer 24

Male reproductive success is opportunity limited

Female reproductive success is resource limited

Question 25

What does optimal foraging theory propose?

Answer 25

That natural selection should act to shape foraging behaviors in ways that maximize benefits and minimize costs

Question 26

What is niche partitioning?

Answer 26

The process by which competing species divide access to available resources. This process may be driven by behavioral or physiological differentiation and plays a role in facilitating co-existence

Question 27

Which can be bigger than the other, the realized or fundamental niche? Why?

Answer 27

THE FUNDAMENTAL NICHE IS BIGGER DUE TO COMPETITION OCCURRING INTRASPECIFICALLY AND BETWEEN INDIVIDUALS

The fundamental niche is the range of physical conditions and resources which individuals of a species can persist
(Competitors, predators, parasites, or disease may limit how much of an organism’s fundamental niche they occupy)

The realized niche is the range of physical conditions and resources within which individuals of a species can persist in the presence of competitors and consumers

Question 28

Draw examples of the three dispersion patterns and list one factor associated with each

Answer 28

Clumped: Individuals are clustered together in groups with distinct gaps between groups
Resource availability
Predation avoidance

Uniform: Individuals are evenly spaced throughout the available habitat
Predation avoidance
Competition

Random: Individuals are distributed randomly throughout the habitat with no apparent pattern
Highly mobile
Low population density
Unpredictable

Question 29

What are the advantages of dispersal?

Answer 29

-Escape disease and predators
-Reduce competition
-Facilitate gene-flow and avoid in-breeding

Question 30

(Be able to explain what each variable represents, how the variables relate to each other, what the equation means/what it might be used to express, and solve the equation using sample data) EQ 1: NPP = GPP – R

Answer 30

NPP= Net Primary Productivity
GPP= Gross Primary Productivity
R= Respiration

Question 31

(Be able to explain what each variable represents, how the variables relate to each other, what the equation means/what it might be used to express, and solve the equation using sample data)
EQ 2: 𝑁 = 𝑀𝐶/𝑅

Answer 31

Mark-Recapture is used to count population size when counting each individual is impractical

N*=True population size
N= Estimate of total population size
M= Total number counted on the first day (and marked afterward)
C= Total number counted on the second day
R= Total number of marked individuals counted on second day