LG 2.1

Question 1

Evolution is a 2 step process. What are these 2 steps?

Answer 1

1) A variation of a gene arises in an individual via mutation or recombination
2) The proportion of this variation in the population changes from generation to generation (it’s inherited)

Question 2

Why is variation important?

Answer 2

Because without variation, there would be no evolution.

Question 3

What is a monophyletic group?

Answer 3

A group on a phylogeny that includes the ancestor and all of it’s descendants

Question 4

On a phylogeny, what do we call a group that includes the ancestor but not all of it’s descendants?

Answer 4

a paraphyletic group

Question 5

Why is it important to have an outgroup on a phylogeny?

Answer 5

To assess the polarity of characteristics and determine the direction of change

Question 6

describe allopatric speciation

Answer 6

when two groups from the same ancestral population evolve into two separate species because of a geographical barrier

Question 7

describe sympatric speciation

Answer 7

when two groups from the same ancestral population evolve into two separate species without the presence geographical barrier

Question 8

What are some forms of sympatric speciation?

Answer 8

-behavioral specialization
-habitual specialization
-polyploidy (plants)

Question 9

What are the 4 major agents of evolution?

Answer 9

migration, mutation, natural selection, genetic drift

Question 10

What are the 2 types of reproductive isolation?

Answer 10

Prezygotic and postzygotic

Question 11

What are some prezygotic barriers to reproductive isolation?

Answer 11

-habitat isolation
-temporal isolation
-mechanical isolation
-behavioral isolation
-gametic isolation

Question 12

What are some postzygotic barriers of reproduction?

Answer 12

-reduced hybrid viability
-reduced hybrid fertility
-hybrid breakdown

Question 13

Describe directional selection

Answer 13

Favors one extreme, selects against the intermediate and other extreme

Question 14

Describe disruptive selection

Answer 14

Favors both extremes, selects against the intermediate

Question 15

Describe stabilizing selection

Answer 15

amplifies the intermediate, selects against both extremes

Question 16

What are Darwins 4 mechanisms for natural selection?

Answer 16

1. There is more offspring than there are resources
2. Individuals in a population vary in traits that affect their ability to compete for resources
3. Individuals with advantageous traits survive and reproduce
4. Offspring inherit those traits, so the frequency of them increase in the population

Question 17

What is the founder effect?

Answer 17

reduction in genomic variability that occurs when a small group of individuals becomes separated from a larger population; bag of jelly beans example