Evolutionary Processes

Exam 2

gene pool concept

all gametes produced by all individuals within a population have the chance to produce offspring

hardy-weinberg representation of a dominant allele

p

hardy-weinberg representation of a recessive allele

q

hardy-weinberg equation: offspring genotype frequency

p² + 2pq + q²

hardy-weinberg representation of a homozygus dominant genotype

p²

hardy-weinberg representation of a homozygus recessive genotype

q²

hardy-weinberg representation of a heterozygous genotype

2pq

hardy-weinberg offspring allele frequency equation (p can be substituted for q)

p = p² + ½ (2pq)

the five assumptions of the hardy-weinberg model

• random mating

• no natural selection

• no genetic drift

• no gene flow

• no mutation

hardy-weinberg functions as a ___ hypothesis, meaning that ___ ___ occurs.

null, no change

the four methods that shift the frequency of alleles within a population

• natural selection

• genetic drift

• gene flow

• mutation

the five patterns of natural selection

• directional

• stabilizing

• disruptive

• balancing

• sexual

directional selection

shifts the average frequency of a trait toward advantageous traits

stabilizing selection

increases the frequency of a commonly occurring advantageous trait

disruptive selection

increases frequencies of multiple advantageous traits

balancing selection

all traits are equally advantageous; no change occurs

intersexual selection

an individual of one sex selects an individual of another sex for mating

intrasexual selection

selection within a sex

genetic drift

the random decrease of allele frequencies; associated with external accidents

the founder effect

a form of genetic drift; change in allele frequencies when a new population is established

genetic bottleneck

a form of genetic drift; a sudden reduction in the number of alleles in a population

genetic drift, gene flow, and mutation are ___ in regard to fitness

random

genetic drift can lead to the random ___ of alleles

fixation

gene flow can lead to the random ___ of alleles

increase

gene flow

the movement of alleles between populations

gene flow ___ the genetic differences between populations and ___ the genetic variation within a population

decreases, increases

if your chi-x² results are within equilibrium, you (can/cannot) reject the null hypothesis.

cannot

mutation

creates entirely new alleles

mutation without gene flow, genetic drift, or natural selection ___ effects a population

rarely

if ___ ceased, evolution would stop occuring

mutation