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Flashcards in Population Genetics Deck (16)
1

Four main evolutionary forces affect allele frequencies:

natural selection, genetic drift, mutation and
gene flow

2

Mutation:

any change in the nucleotide sequence and/or arrangement of DNA (as compared to some reference standard).

3

Polymorphism:

A genetic variant (mutation) which is common (>1%) in the populations

4

Founder effects:

a high frequency of a mutant allele in a population founded by a small ancestral group when one or more of the original founders was a carrier of the mutant allele (Ghengis khan?)

5

Genetic drift:

random fluctuation of allele frequencies, usually in small populations

6

Selection:

active selection of favorable alleles over non-favorable ones

7

fitness:

a measure of the chance an allele will be transmitted to the
next generation (Scale is 0-1). Fitness measures reproductive success.

8

Idealized Assumptions in Hardy-Weinberg Equilibrium (HWE):

Large population mating randomly.
• Allele frequencies remain constant over time because:
o No appreciable rate of new mutation
o No selection for/against any allele
o No appreciable immigration/emigration of persons from population with different allele frequencies

9

Stratification

refers to populations containing 2 or more subgroups which tend preferentially mate within their own subgroup. Mate selection is not dependent on the trait/disease or
interest. (Example: sickle cell anemia in African Americans (AAs) has higher incidence social stratification favoring mating of AAs with other AAs, than is predicted by HWE)

10

Assortive mating

refers to when the choice of mate is dependent (in part) on a particular trait (or sometimes a disease). This occurs because people tend to choose mates who resemble
themselves for (language, intelligence, height, skin color, etc.). This has been observed for congenital short stature (previously called ‘dwarfism’), blindness, and deafness

11

Two equations of Hardy-Weinberg?

p2 + 2pq + q2 = 1 and p + q = 1

12

p =

frequency of the dominant allele in the population

13

q =

frequency of the recessive allele in the population

14

p^2 =

percentage of homozygous dominant individuals

15

q^2 =

percentage of homozygous recessive individuals

16

2pq =

percentage of heterozygous individuals