Speciation

MECHANISMS OF CHANGE (How Things Change) Population Genetics Genetic Drift Gene Flow Nonrandom Mating Mutation Natural Selection Four reasons (mechanisms) of change: Competition. Variation in population. Trait must be genetic. Over production of offspring.

EVIDENCE OF CHANGE Fossils Molecular Evidence Similarities in DNA Sequences Comparative Anatomy Vestigial Structures Homologous Structures Analogous Structures Comparative Embryology

Speciation Species: A population or group of populations whose members can interbreed and produce fertile offspring. Speciation: The formation of new species. Sometimes groups will separate from one another, we call this reproductive isolation. Can be Behavioral, Geographic, or temporal.

Behavioral Isolation Two species are capable of breeding but have differences sexual selection patterns. Courtship rituals Calls Dances Fighting Etc… Example: Meadowlarks – different mating calls.

Geographic isolation Two populations that are capable of mating are separated by geographic barriers such as rivers, mountains, or bodies of water. Example: KAIBAB and ABERT’S squirrels in the grand canyon. Example: Fish in lakes (doesn’t always work)

Temporal Isolation Temporal isolation is when two or more species reproduce at different times. Example Flowers that allow pollination at different times of the year.

Speciation Isolation generally causes speciation. Mutations can occur but separation or new mating partners can cause the most amount of speciation.