Genetic theory natural selection 2

Question 1

inheritance patterns and what proportions alleles end up relies on…

Answer 1

• depends on where alleles start
• and which alleles are favoured due to context (the environment)

Question 2

new beneficial mutations are likely to be lost due to ….

Answer 2

DRIFT IN SMALL POPULATIONS

Question 3

what is a major factor that maintains variation in populations? an example?

Answer 3

• negative frequency dependent selection
• where the relative fitness of a trait is high when it is rare, but low when it is common
• selection will favour different phenotypes (higher frequency=lower fitness), but this causes changes in frequencies to occur from year to year

Question 4

the rate of evolution (genetic change) in a population depends on ….

Answer 4

• the strength of selection
• and the amount of genetic variation

Question 5

how did Goldschmidt assume adaptations evolved?

Answer 5

• thought through new adaptations, new species evolved through MASSIVE changes. “Hopeful monsters theory”

Question 6

in an adaptive landscape, how to you get from peak to peak?

Answer 6

gene flow, drift, and mutation

Question 7

what is Wright’s shifting balance theory?

Answer 7

• that adaptation involved a shifting balance between evolutionary forces

Question 8

what are the phases of shifting balance theory?

Answer 8

phase 1: random genetic drift allows a population to explore the adaptive landscape, crossing the valleys

Phase 2: selection within that population moves it up the hillside to a higher adaptive peak

Phase 3: Interdemic selection: this pop now has higher fitness than other pops, meaning a higher growth rate, producing more migrants (gene flow). these migrants move to other populations

Question 9

what is the largest criticism of shifting balance theory?

Answer 9

• criticism focused on phase 3
• due to co-adapted gene complexes, traits adaptive in one area may not be adapted in other areas

Question 10

what are three components of genetic variation?

Answer 10

• additive genetic variation (variation due to the additive effects of alleles)
• dominance genetic variation (variation due to dominance relationships among alleles)
• epistatic genetic variation (variation due to interactions among loci)

Question 11

a trait that has lower heritability means

Answer 11

it is more effected by environment, and less-so genetics

Question 12

life history traits that have been under selection for a long time means

Answer 12

there is less variation in the trait