Anthropology 240 - Population Genetics & Forces of Evolution (Ch. 4)

Population Genetics & Forces of Evolution (Ch. 4)

Natural Selection

An evolutionary process that occurs when certain phenotypes confer an advantage or disadvantage in survival and/or reproductive success. This is one of the forces of evolution, and it was first identified by Charles Darwin.

Micro & Macroevolution

Microevolution- Changes in allele frequencies within breeding populations, a single species ( Macroevolution - Changes that result in new species)

Gene Flow

refers to the movement of alleles from one population to another. In most cases, gene flow can be considered synonymous with migration.

Viable Offspring

offspring that are healthy enough to survive to adulthood

Fertile offspring

are able to reproduce successfully, resulting in offspring of their own- needed for evolution

Gene Pool

refers to the entire collection of genetic material in a breeding community that can be passed on from one generation to the next.

Population

a group of individuals of the same species who are geographically near enough to one another that they can breed and produce new generations of individuals.

Inbreeding

the selection of mates exclusively from within a small, closed population—that is, from a group with limited allelic variability

Population Bottleneck

when the number of individuals in a population drops dramatically due to some random event

Genetic Drift

refers to random changes (“drift”) in allele frequencies from one generation to the next.

The genes are remaining constant within the population; it is only the alleles of the genes that are changing in frequency.

The random nature of genetic drift is a crucial point to understand: it specifically occurs when none of the variant alleles confer an advantage.

Evolution

a change in the allele frequencies in a population over time.- always studied at the level of populations

Modern Synthesis

The integration of Darwin’s, Mendel’s, and subsequent research into a unified theory of evolution.

Allele ratio/frequency

the ratio (or %) of one allele (one variant of a gene) compared to the other alleles for that gene

Founder Effect

when members of a population leave the main or “parent” group and form a new population that no longer interbreeds with the other members of the original group.

Species

Organisms whose individuals are capable of breeding because they are biologically and behaviorally compatible to produce viable, fertile offspring.

Mutation

change, into the genetic code—that new alleles were introduced into the population- A This is one of the forces of evolution.