AP Biology Unit 7

Artificial selection

Evidence for evolution, humans pick the traits to see how population changes over time

Fossil record

Evidence for evolution, see how things change every time through fossils

Homology

Evidence for evolution, groups have the same structure because they share a common ancestor

What factors determine genetic variability?

How often mutations happen, how quickly things reproduce

Polygenic Trait

Trait that is controlled by multiple genes

What are the 5 premises of HW Equilibrium?

no mutations, large population, no natural selection, random mating, no gene flow

What causes allele frequencies to change?

Any of the 5 HW conditions not being met

What is a gene pool?

all of the genes of the individuals in a population

Why is genetic variability important?

Evolution comes to a stop without it

Genetic drift

Changes in allele frequencies due to random, non-selective events

Population Bottleneck

Type of genetic drift, sharp reduction in population size due to environmental events, such as floods and earthquakes

Founder Effect

Type of genetic drift, small group leaves the population to start a new colony

Gene flow

movement of genes causing change in allele frequency, gene flow from outside population increases genetic variation

Directional selection

Shifts frequency of one or more traits in a particular population, e.x. body size

Stabilizing selection

Acts against extremes so that average is favored

Disruptive selection

Increases frequency of extreme phenotypes and may lead to new species

Coevolution

Selection force comes from another living organism, organisms evolve to one another

Mutualism

Each species has a benefit

Commensalism

One organism benefits and the other doesn’t benefit nor is harmed

Parasitism

One organism benefits and the other is harmed

Sexual selection

The differing ability of individuals with different genotypes to acquire mates and reproduce

What are the types of sexual selection?

Female choice and male competition

Microevolution

How populations evolve

Macroevolution

How species evolve

What are the types of reproductive barriers?

Prezygotic which prevents fusion of sperm and egg and postzygotic which is when the zygote will die or be sterile

Speciation

Formation of new species

How does speciation occur?

Two populations become reproductively isolated, gene flow stops and allele frequency changes and prevents the groups from being able to reproduce

Allopatric speciation

New species formed due to geographic barrier

Sympatric speciation

Formation of new species without the geographic barrier

Divergent evolution

Separation of one species into two or more

Adaptive radiation

Rapid divergence into many species with varying adaptions due to unoccupied niches

Dispersal

Spread of taxon over a large area

Vicariance

Fragmentation of widely dispersed species

Convergent evolution

Independent development of similar features in separate lineages