bio II ch 2 review

how does sexual recombination generate genetic variability?

sexual recombination constantly generates new variations in the population by combining one half of each parent’s genes in the offspring

population

localized group of individuals capable of interbreeding and producing fertile offspring

species

a group of individuals that can interbreed

gene pool

sum total of genes in a population at one time

relative fitness

total number of offspring an organism has compared to the average number of offspring for the population

heterozygote advantage

occurs when heterozygote have a higher fitness than do both homozygotes

5 conditions of hardy-weinberg equilibrium

1) no mutation

2) gene flow

3) no natural selection

4) random mating

5) extremely large population size

role of population size in genetic drift

founder effect & bottleneck effect

founder effect

occurs when a few individuals become isolated from a larger population

bottleneck effect

sudden reduction in population size due to a change in the environment

directional selection

favors individuals at one end of the phenotypic range

stabilizing selection

favors intermediate variants and acts against extreme phenotypes

disruptive selection

favors individuals at both extremes of the phenotypic range

intrasexual selection

competition among individuals of one sex (often males) for mates of the opposite sex

intersexual selection

occurs when individuals of one sex (usually females) are choosy in selecting their mates

reasons why natural selection can’t produce perfect organisms

1) selection can act only on existing variations

2) evolution is limited by historical constraints

3) adaptations are often compromises

4) chance, natural selection, and the environment interact

after surviving a bottleneck, a population recovers to the point where it consists of as many individuals as it did prior to the bottleneck. which of the following statements is most likely to apply to this population:

a) the bottleneck subjected the population to stabilizing selection

b) the post-bottleneck population exhibits more genetic variation than the pre-bottleneck population

c) the post-bottleneck population has less of a chance of going extinct than did the pre-bottleneck population

d) the post-bottleneck populations exhibits less genetic variation than the pre-bottleneck population

d

gene flow is accomplished by

a) sexual recombination

b) mutation

c) migration

d) natural selection

c

the founder effect differs from a population bottleneck in that the founder effect

a) is a type of natural selection

b) involves the isolation of a small colony of individuals from a larger population

c) can only occur on an oceanic island colony

d) requires a small population

b

the modern synthesis was a fusion of

a) molecular biology and comparative anatomy

b) genetics and evolutionary biology

c) the fossil record and genetics

d) population ecology and genetics

b

the smallest biological unit that can evolve is the

a) population

b) individuals

c) phylum

d) species

a

the total collection of alleles in a population at any one time make up that population’s

a) heterozygosity

b) genotype

c) gene pool

d) polymorphic pool

c

which of the following is an example of directional selection?

a) garter snakes with different coloration patterns behave different when threatened

b) the birth weight at which newborn humans are most likely to survive and the average weight of newborn humans are about the same

c) there is an increase in the number of different breeds of dog

d) there is an increase in antibiotic-resistant strains of bacteria

d

which of the following is an example of sexual selection?

a) peahens choose to mate with peacocks that have the most beautiful tails

b) cheetahs experienced a population bottleneck

c) bacteria evolve resistance to antibiotics

d) female butterflies have a higher survival rate than male butterflies

a

which of the following is an example of stabilizing selection?

a) there is an increase in the number of different breeds of dog

b) there is an increase in antibiotic-resistant strains of bacteria

c) the birth weight at which newborn humans are most likely to survive and the average weight of newborn humans are about the same

d) garter snakes with different coloration patterns behave differently when threatened

c

which one of the following can create new alleles?

a) natural selection

b) mutation

c) sexual reproduction

d) genetic drift

b