Descent with modification - caused by evolution (one way = natural selection).

Changes over time-accumulated differences-give rise to new species/traits.

Evolution

• All organisms originate from a common ancestor.
• Traits have variability over time.
• Evolution causes constant fluctuations of alleles in the gene pool / population.
• Changes in inherited traits and descent with modification lead to changes in allele frequencies.

Ways Allele Frequencies Change

• Sexual selection (non-random mating)
• Natural selection
• Mutations
• Genetic Drift (chance events)
• Gene Flow (moving societies)
• Inbreeding (non-random mating) (does not change the gene pool, inverse of the others)

How to Evaluate Evolution

Evaluate genetic composition in a population.

Microevolution

Changes in Allele Frequencies

Macroevolution

Over time, how new species develop.

Population

A group of individuals of the same species that live in the same areas and interbreeds.

Gene Pool

All copies of every allele in all members of a population.

Population Genetics

How allele frequencies change in a population over time.

Genotype Frequency

Count individual genotypes.

Allelic Frequency

Count of alleles (2m = 2x num) - Rr#

Mutations

Changes in allele frequencies.

Natural Selection

Individuals with traits better suited to an environment go on to reproduce.

Adaptions

If a trait is useful to reproductive success.

Sexual Selection (pretty traits)

Natural Selection (survival of the fittest)

Non-Adaptive

If a trait is not useful to reproductive success.

Mutations (random chance)

Genetic Drift ()

Gene Flow ()

Species

Does produce viable offspring amongst themselves.

Does not produce viable offspring by breeding with different species.

Speciation

Process by which one species splits into two species.

Defining factor between microevolution and macroevolution.

Gene Flow

Movement of alleles between populations.

Group moves into an established population (joins another).

Affects the population of alleles in both populations.

Increases variation within populations and decreases variations between populations.

Genetic Drift

Acts more strongly on smaller populations.

Easy to become fixed (no genetic variation).

Random chance events cause allele frequencies to fluctuate.

Decreases variation within populations and decreases variations between populations.

Founder Effect Random Chance Event

Individuals from an original population leave and start a new population elsewhere.

Population Bottleneck Random Chance Event

There's a drastic reduction in population size.

It's likely few alleles are left and they become fixed.