Natural Selection Vocabulary

Flashcards covering key vocabulary and concepts from the Natural Selection and Evolution lecture

Evolution

The process of biological change in populations over time that makes descendants genetically different from their ancestors.

Microevolution

Evolution on a small scale affecting a single population.

Macroevolution

Evolution on a large scale affecting changes in species across populations.

Natural Selection

Organisms with the “best” traits (adaptations) will live longer and reproduce more than others, causing changes in the population over time by acting on traits that are heritable.

Fitness

A measure of how well you can survive in your environment and pass on your genes.

Variation

Differences in the physical traits of organisms; Random mutations, genetic recombination during meiosis and migration.

Adaptation

A feature that allows an organism to better survive in its environment.

Gene Pool

The combined alleles of all individuals in a population.

Directional Selection

Increases the expression of an extreme version of a trait in a population.

Disruptive Selection

A process that splits a population into two groups; removes individuals with average traits and favors the 2 extremes.

Stabilizing Selection

Eliminates extreme expressions of a trait when the average expression leads to higher fitness.

Allele Frequency

The number of times the allele appears in a population; how common it is.

Mutation

Any change in a DNA sequence; creates new genotypes and thus new phenotypes.

Genetic Drift

Random change in the frequency of alleles in a population over time, usually a sharp decrease in population size.

Gene Flow

Movement of genes into/out of a population; occurs during migration.

Sexual Selection

The selection of traits that aren’t necessarily good for survival fitness, but without them, you can’t pass on your genes at all because you can’t reproduce.

Genetic Equilibrium

When there are NO changes in the allele frequencies in a population over time (Hardy-Weinberg equilibrium).

Hardy-Weinberg Equilibrium (HWE)

p + q = 1, p2 + 2pq + q2 = 1

p

Frequency of the dominant allele

q

Frequency of the recessive allele

p2

Genotypic frequency of homozygous dominant individuals

2pq

Genotypic frequency of heterozygous individuals

q2

Genotypic frequency of homozygous recessive individuals