Lecture 20 population structure, gene flow and genetic drift

Question 1

What is migration?

Answer 1

the movement of individuals from one population to another

Question 1

What is a population?

Answer 1

a group of individuals of the same species occupying a given area at the same time

Question 2

What is gene flow?

Answer 2

any mechanism that allows genes to flow from one population to another

Question 3

What are Key questions for evolutionary studies of variation within populations? (2)

Answer 3

How many of these variations are genetic in origin?

Does variation contribute to fitness differences among organisms?

Question 4

What are Key questions for geographical differentiation? (2)

Answer 4

What proportion of genetic variation in a species is found within a population vs between populations?
How is diversity distributed within and between populations?
Are the differences between populations heritable and adaptable?

Question 5

What is the job of gene flow?

Answer 5

to homogenize

Question 6

How does drift affect populations?

Answer 6

causes populations to be different

Question 7

What are ways to measure gene flow?

Answer 7

Experiments

Neutral genetic markers

Polymorphic genetic variants that are not direct targets of selection

Question 8

If two populations have different genes, one fully F and only fully G what gene will the offspring have?

Answer 8

FG gene

Question 9

If there is a field of crop and weed sunflowers, what happens to gene flow the further these are from each other?

Answer 9

Less gene flow

Question 10

What is genetic drift?

Answer 10

Random fluctuations in alleles

Question 11

Does genetic drift lead to particular direction of evolutionary change?

Answer 11

No

Question 12

What are stochastic evolutionary forces? MRG

Answer 12

Mutations

Recombination

Genetic drift

Question 13

What is a deterministic evolutionary force?

Answer 13

Natural selection

Question 14

What are Stochastic changes in allele frequency due to?

Answer 14

random variation in fecundity and mortality

Question 15

What type of population size do stochastic changes affect?

Answer 15

Small populations

Question 16

What is Population bottlenecks?

Answer 16

A single sharp reduction in abundance followed by a rebound

Question 17

How does Population bottlenecks affect biodiversity?

Answer 17

Results in loss of biodiversity

Question 18

What is the Founder effect?

Answer 18

When a few individuals from a population colonize a new area

Question 19

What is the diversity like in the colonizing group compared to the source group?

Answer 19

colonizing group contains only limited diversity compared to the source group

Question 20

Which type of population size is genetic drift more common in?

Answer 20

Genetic drift more prominent in small populations

Question 21

What are the effects of genetic drift? (4) FDAC

Answer 21

More drastic fluctuations each generation

Rapid loss of genetic diversity

Faster allele fixation of loss

Less consistency across replicate populations

Question 22

what factors make a phenotype?

Answer 22

genomic and environmental factors

Question 23

do genotypes grow the same in every environment?

Answer 23

no

Question 24

what is phenotypic plasticity?

Answer 24

ability of a genotype to modify its phenotype in response to environmental changes

Question 25

what organism is phenotypic plasticity most common in?

Answer 25

plants and corals

Question 26

do all phenotypic plasticity result from adaptation

Answer 26

no

Question 27

what is done in reciprocal transplant studies?

Answer 27

Growing gene types in different environments and comparing the phenotypes in different environments

Question 28

Reciprocal transplant studies provide evidence of?

Answer 28

local adaptation

Question 29

what do reciprocal transplants enable?

Answer 29

Enables measurement of selection against non-local genotypes

Question 30

what components does Reciprocal Transplant Studies separate phenotypic variation into?

Answer 30

genetic and environmental components

Question 31

what were the conclusions in the Clausen-Keck-Hiesey Transplant?

Answer 31

Differences between populations are due to BOTH plasticity and genetics

Evidence from widespread local adaptation because local populations had the highest fitness

Question 32

what does high UV radiation select for in terms of skin pigmentation? what does it interfere with?

Answer 32

May select for increased pigmentation

Interferes with folate (the natural form of vitamin B9, water-soluble and naturally found in many foods)

Question 33

what does low UV radiation select for in terms of skin pigmentation? what does it reduce the making of?

Answer 33

Reduced making of vitamin D

Increase selection for reduced pigmentation

Question 34

is there a single best phenotype across the globe? why

Answer 34

No single best phenotype across the globe due to tradeoffs

Question 35

what was the history of Local adaptation on skin pigmentation?(4) NADl

Answer 35

Numerous genes are known to affect skin pigmentation.

Alleles of these genes show rapid allele frequency change over time using ancient genomes (indicates natural selection).

Alleles of these genes show higher between population differentiation than most other genes.

Evidence supporting a history of local adaptation