Chapter23

Question 1

Genetic Drift

Answer 1

increases frequency of alleles that contribute to reproductive success in a particular environment

occurs in every population

most pronounced in small pops

results in decrease in genetic variation

Question 2

Gene Flow

Answer 2

Organisms leave one pop, join another an breed
movement of alleles between populations
equalizes allele frequencies between source and recipient populations
can increase or decrease fitness depending on situation

Question 3

Mutation

Answer 3

Modifies allele frequency by introducing new alleles
restores genetic diversity
random
deleterious alleles usually eliminated by purifying selection
ultimate source of genetic variation

Question 4

Hardy–Weinberg principle(bad)

Answer 4

1. random mating - no mate choice
2. no natural selection - individuals contribute equally to gene pool
3. no genetic drift - random allele freq change
4. no gene flow - no new alleles
5. no mutation - no new alleles

Question 5

inbreeding

Answer 5

increases homozygotes, decrease heterozygotes
can speed evolutionary change
decline in average fitness

Question 6

natural selection

Answer 6

heritable variation leads to differential survival and reproduction
increased allele frequency for favorable phenotypes

Question 7

Directional Selection

Answer 7

changes average phenotype in one direction
reduces genetic diversity of populations
purifying selection as disadvantageous alleles approach zero

Question 8

Stabilizing selection

Answer 8

reduces genetic variation in trait
reduces extremes on population

Question 9

disruptive selection

Answer 9

extreme phenotypes are favored
opposite of stabilizing selection
increased variation of trait

Question 10

Balancing selection

Answer 10

no single allele has a distinct advantage
heterozygote advantage

Question 11

intersexual selection

Answer 11

mate choice

Question 12

intrasexual selection

Answer 12

individuals of the same sex compete

Question 13

Bateman–Trivers hypothesis(Fundamental Asymmetry of Sex)

Answer 13

traits to attract opposite sex are more elaborate in males bc eggs are more costly to produce than sperm. males limited to amount of mates they can find, females limited to the eggs they produce

male to male competition increases population

sexual selection is stronger on males

Question 14

Sexual selection in seals

Answer 14

male seals fight for territory
males that lose don’t reproduce as much

Question 15

Sexual dismorphism

Answer 15

differences across sexes of a species

Question 16

founder event

Answer 16

individuals establish a new population in a new area
allele frequencies change resulting in whats known as a founder effect(type of genetic drift)

Question 17

population bottleneck

Answer 17

sudden decrease in pop size
caused by disease, disaster

Question 18

genetic bottleneck

Answer 18

caused by population bottleneck
sudden reduction of alleles
change in allele frequency