Mechanisms of Evolution

Genetic Drift

Through random change, only part of a population survives to have offspring, and the survivors do not reflect the same percentages of alleles as the original population

Gene flow

The exchange of genetic material between populations (an organism comes from one population to another, and may bring a new allele)

Mutation

A mistake in an organism's DNA that is passed to its offspring

Natural selection

When a trait becomes more common because it is beneficial for the environment

Bottleneck effect

When a population is significantly reduced for one generation.

Founder effect

When a few members of a population move to start a new population

Why are the bottleneck and founder effects examples of genetic drift?

The smaller population sizes do not reflect the allele frequencies of the original population.

Does gene flow or the lack thereof allow for evolution?

Both; gene flow introduces new alleles to a population, but lack of gene flow allows for speciation

Role of genetic drift

changes allele ratios, creates randomness

Role of gene flow

movement of alleles

Role of mutations

change Dna, creates new alleles

Role of natural selection

survival of the fittest, promotes fit individuals

4 Components of natural selection

variation exists within a trait, variation creates differences in survival, the fit individuals survive but the others die, fit individuals are able to pass on their traits

Biological fitness

The ability of an organism to produce offspring that can produce offspring (cares about grandchildren)