21.2

Question 1

mechanisms of evolution

Answer 1

mutation
gene flow
genetic drift
selection
nonrandom mating

Question 2

mutation

Answer 2

-any change in the base sequence of DNA
-ultimate source of variation; gives rise to different alleles
-mutations are rare and not the primary cause of changes in allele frequency within a population

Question 3

gene flow

Answer 3

-movement of alleles from one population to another
-occur when an organism moves to a new location or when pollen and seeds are dispersed

Question 4

genetic drift

Answer 4

-change in allele frequencies due to sampling error (random chance)
-largest effect in populations
-given sufficient time, genetic drift alone can cause substantial changes to allele frequencies
*alleles will drift to fixation or loos
*frequency of heterozygotes declines
Founder effect
bottleneck effect

Question 5

founder effect

Answer 5

when a new population established by a small number of individuals it is unlikely that they carry all the alleles found in the parent population
not rare in nature
-self pollinating plants often start populations from a single seed

Question 6

bottleneck effect

Answer 6

when a small number of individuals are contributing gametes to the next generation, the alleles they carry may not represent all the alleles found in the parent population

Question 7

selection

Answer 7

the number of offspring an organism leaves behind is affected by phenotype and behavior