Evolution- AP BIO

Evolution

The change in gene frequencies in a population over time.

Gene

A piece of DNA that codes for a trait.

Allele

A variation of a gene (you have 2 alleles for every gene, 1 from mom + 1 from dad)

Species

Organisms that can breed and produce fertile offspring.

Population

Organisms of the same species that live together.

Natural Selection

Organisms with certain traits produce the most offspring.

Artificial Selection

Humans determine the best characteristics that survive and reproduce.

Fossils

Allow us to find similarities and differences between what we see today and what lived in the past - youngest most recent layers of rock are on top, oldest remains are deeper.

Embryology

Allow us to see similarities in unborn animals to determine which species are related to each other.

Homologous Structures

Allow us to see similarities in different body parts even if the body parts serve different functions.

Vestigial Structures

Allow us to see how body parts that seem useless may have been useful in ancestral organisms.

Molecular Evidence

Allow us to see similarities and differences in DNA and proteins.

Gene pool

All the genes in a population.

Hardy Weinberg

Mathematical model of gene pool changes over time.

Genetic Drift: Bottleneck Effect

Extreme reduction via humans or natural disaster.

Genetic Drift: Founder Effect

Part of the population becomes separated from the original population.

Gene Flow

Movement of DNA from one population to another through immigration / emigration.

Mutations

Errors in DNA or proteins that can cause a different trait to appear.

Sexual selection

One sex favors a particular trait in the opposite sex so that trait becomes more common.

Stabilizing Selection

Favors the average, against the extremes. For example, human babies.

Directional Selection

Select toward one extreme. For example, tallest giraffe.

Diversifying (Disruptive) Selection

Selection towards both extremes, against the average.