Exam 2 ch 7 Flashcards
constant frequency of an allele in a population over time
genetic equilibrium
the movement of alleles from one population to another
migration
hardy Weinberg assumes that for genetic equilibrium there must be no?
migration
migration changes?
the allele frequencies in a population
For small populations receiving immigrants from large source populations, migration can be a potent?
mechanism of evolution
In groups of populations, gene flow (migration) tends to _________________________________ preventing the evolutionary divergence of populations.
homogenize allele frequencies
Migration is most important in preventing populations from __________(evolving into separate
species)
diverging
Humans are creating isolated populations, limiting migration and gene pools, and ________________________ of surviving isolated populations
increasing evolutionary divergence
Random change in allele frequency due to chance; results in nonadaptive evolution
genetic drift
can cause the disappearance or fixation of alleles
genetic drift
When an allele becomes the only variant that exists for that gene in a population
fixation
what causes random fixation
drift
the fixation of a mutated version of a gene
substitution
random discrepancies between theoretical and observed values
sampling error
Sampling error can result in
genetic drift
Natural sampling errors example
earthquakes, floods, landslides, or other natural disasters subdivide a population
A large-scale but short-term reduction in population size that eliminates many
alleles
genetic bottleneck
After first contacts with Europeans and Africans, _____________ of the native population of the New World died due to Old World
diseases
~90–95%
Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of the original
population
founder effect
mutations that reduce the fitness of an individual are less likely to be transmitted to successive generations and the mutant trait will be quickly lost
Purifying Selection (Negative Selection)
Mutations that increase the fitness of an individual are more likely to be transmitted to successive generations and the mutant trait is more likely to become fixed
positive selection
When an allele changes frequency because a neighboring gene is undergoing a selective pressure
genetic hitchhiking
Changes in a gene’s DNA sequence that do not change the amino acid
silent mutations
Differences in the frequency of occurrence of synonymous codons in coding DNA
codon bias
Codon bias is strongest in?
highly expressed genes
Mating pattern in which some individuals are more or less likely to mate with
individuals of a particular genotype than with individuals of other genotypes
nonrandom mating
Mating among genetic relatives
inbreeding
self fertilization
selfing
Reduced fitness in individuals because homozygotes for deleterious alleles
become more common or because heterozygotes have improved fitness
inbreeding depression
