Evolution AP Bio thing I need to study...

t-val < t-critical means

we fail to reject Ho

Neutral Variation

nucleotide differences which provide no selective advantage (due to noncoding DNA or silent mutations)

Disruptive selection

Both extremes are favored, creates bimodal graph

ex. dark & light fur favored, not medium fur

Stabilizing selection

Average phenotype favored while decreasing diversity

ex. birth weight

Directional selection

One extreme favored, skewed graph

Sexual selection

Certain traits are more likely to be mated with

ex. gender dimorphism in animals

Intrasexual selection

Competition for mates in the same gender

Intersexual selection

Female chooses male

Balancing selection

Multiple alleles are maintained from becoming lost

“Allele fixation”

Heterozygote selection

Heterozygotes survive and reproduce more than homozygous

ex. sickle cell

Frequency dependent selection

phenotype fitness decreases as it becomes too abundant

ex. left/right mouthed fish

Diploidy

Genetic variation hidden in heterozygotes maintains a large pool of alleles

Bottleneck Effect

Type of genetic drift. Happens when a random chance event happens which drastically changes allele frequencies due to population size changes

ex. natural disaster

Founder Effect

Few individuals separate from main population. Makes genetic variation very small