Evolution Exam study guide

Question 1

Three things that must be true for natural selection to occur

Answer 1

A population must have variation in a trait.
-That variation must be heritable.
-Some variants must be better able to survive and reproduce than others (i.e. have higher fitness).

Question 2

Mutation

Answer 2

They can be deleterious (bad), beneficial (good), or have no effect (neutral).
Mutation rates vary, but even low rates create considerable variation.
Mutations in genes create new alleles of those genes.

Question 3

Directional selection

Think about the Moths and changing of color

Answer 3

individuals at one extreme of a character distribution contribute more offspring to the next generation.
It operates over many generations, an evolutionary trend is seen.

Question 4

Stablizing selection

Answer 4

fitness graph is a wide bell shape curve with dot scattered randomly on curve, frequency graph is when the bell curve moves inward. favors average individuals

Question 5

Disruptive selection

Think about 2 different alternatives

Answer 5

Individuals at the extremes of a character distribution have the highest fitness.

Results in increased variation in the population
Can result in a bimodal distribution of traits

Question 6

For a population to be at Hardy-Weinberg equilibrium, there must be:

Answer 6

random mating
-no mutation
-no gene flow (i.e. migration)
-no selection
-infinite population size

Question 7

Genetic drift

Answer 7

(random) changes in allele frequencies from one generation to the next.
tends to eliminate genetic variation

Question 8

Genetic Bottlenecking

Answer 8

an environmental event results in survival of only a few individuals
Populations that go through this lose much of their genetic variation.

Combination of 2 factors:

• random sampling
• increased effect of
  genetic drift.

Question 9

Founder effect

Answer 9

small number of migrants start a new population.
New population is fixed for different alleles than original population.

Question 10

Gene flow

Answer 10

Migration of individuals between populations results in this, which can change allele frequencies.

The effect that gene flow has depends on the number of migrants and the size of the population.

Question 11

Artifical selection

Answer 11

A breeder selects for certain traits of the offspring. Human interference

Question 12

Darwinian Evolution

Answer 12

Natrual selection and Evoultion theory. Descent of modfication

Question 13

Malthus

Answer 13

Limits of food supply with higher population. Carrying capacity

Question 14

Fitness

Answer 14

Reproductive success represented by the survival of the offspring

Question 15

Adaption

Answer 15

Changes in the environent to better suit your species

Question 16

Non random mating

And sexual selection

Answer 16

which individuals with certain traits have more success in competition for a mate or in the choice of a mate based on a preference for those traits. Sexual selection acts on an individual’s ability to reproduce by gaining access to gametes for fertilization

Question 17

Gene pool

Answer 17

The group of alleles shared by all the indivuials within the population. Allele frequency may shift until the population has overall average phenotype that looks quite different