Ch 25 Population Genetics Flashcards
branch of genetics that studies genetic makeup of groups of individuals and how genetic composition of a group changes over time
population genetics
group of interbreeding, sexually reproducing individuals that have a common set of genes
Mendelian population
what leads to a loss of genetic variation?
genetic drift
what is the basis for all evolution?
genetic variation
what are the assumptions of the Hardy-Weinberg law?
- large population
- randomly mating
- not affected by mutation, migration, or natural selection
if a population is in Hardy-Weinberg equilibrium, what does it mean about the population?
the population is not evolving
when is the heterozygote frequency at its maximum?
when each allele frequency (p & q) are 0.5
if a population is in Hardy Weinberg equilibrium, have forces (natural selection, mutation, and migration) have acted since random mating last took place?
no, these forces have no acted since random mating last took place
describe the two types of nonrandom mating
positive assortment mating - tendency for like individuals to mate
negative assortment mating - tendency for unlike individuals to mate
preferential mating between related individuals
inbreeding
preferential mating between unrelated individuals
outcrossing
when inbreeding occurs, does the heterozygote population increase or decrease?
heterozygotes decrease
describe inbreeding depression and what causes it
decreased fitness of a population due to inbreeding, often because of increased appearance of lethal or deleterious traits
describe how mutations change allelic frequencies
mutations can increase the allele frequency at one locus, thus decreasing the frequency of the other, until they eventually reach mutational equilibrium
what is gene flow/migration?
movement of genes from one population to another
what are the two overall effects of migration?
- prevents populations from being genetically different from one another
- increases genetic variation within a population
what is genetic drift?
change in allele frequencies due to chance when sample size is small
what is founder effect?
establishment of a population by a small number of individuals, where the genes depend on the genes of the founders
what is bottleneck effect?
a population undergoes a drastic reduction in size, where the genes depend on the survivors
what are the effects of genetic variation?
- change in allelic frequencies
- reduction in genetic variation within populations
- different populations diverge genetically from one another
occurs when an allele reaches a frequency of 1; all are homozygous for that one allele
fixation
what is natural selection?
differential reproduction of genotypes, where individuals with adaptive traits reproduce more than others
relative reproductive success of a genotype
fitness
