Bio107 Quiz 2

Genetic drift

any change in allele frequencies that is due to chance

sampling effect/error

phenomenon that causes the chance events that cause genetic drift

Founder events

• one type of event that can cause genetic drift

• occurs when a relatively small number of individuals disperse to a new habitat

Genetic bottlenecks

• one of several types of events that can cause genetic drift

• occur when a species undergoes a large and rapid decrease in population size due to a disease, epidemic, catastrophic storm, or other change

Genetic drift is more important in (small/large) populations?

small

How might genetic drift affect alleles?

genetic drift reduces genetic variation when it leads to fixation and loss of alleles

gene flow

an evolutionary process that changes allele frequencies through the movement of individuals and their alleles from one population to another

• homogenizes allele frequencies among populations

Mutation

• any change in nucleotide sequence/genetic information in DNA

• only process that creates entirely new alleles

Deleterious mutation

mutation that reduces fitness

Neutral mutation

mutation that has no impact on fitness

Beneficial mutation

mutation that increases fitness

Most mutations are ___.

deleterious

Maladaptive

leading to lower fitness

four evolutionary forces

• natural selection

• genetic drift

• gene flow

• mutation

Anthropocene

a proposed interval in Earth’s history where environments are species are undergoing massive and widespread change due to human activities

Inbreeding depression

reductions in the average fitness of individuals in a population, due to the increased prevalence of homozygous recessive genotypes that have deleterious effects

extinction vortex

in some genetically isolated populations, a self-reinforcing cycle that lowers fitness and population size

wildlife corridor

a physical connection between habitat patches

Inbreeding depression

decrease in health and fitness in offspring resulting from inbreeding

artificial selection

selective breeding by humans

Null model

a model that predicts the data that you should expect to see if a process is not working—meaning, when a particular causative agent is not impacting the situation

Hardy-Weinberg Principle

a null model stating that is no selection, drift, gene flow, or mutation occur, and if mating is random with respect to to the gene in question, then the allele frequencies will not change from one generation to the next and genotype frequencies will be in the proportion p2, 2pg, q2, where p and q are the frequencies of the two alleles at that gene.

gene pool

a concept used in predicting the results from random matings among all of the individuals in a population, by supporting that all gametes are tossed into a “pool” and then drawn out at random to produce offspring

stabilizing selection

favors average phenotype and reduces genetic variation

directional selection

favors one extreme phenotype and shifts the population’s trait distribution in a single direction