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Speciation
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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.
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EVIDENCE OF CHANGE Fossils Molecular Evidence
Similarities in DNA Sequences Comparative Anatomy Vestigial Structures Homologous Structures Analogous Structures Comparative Embryology
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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.
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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.
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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)
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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.
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Speciation Isolation generally causes speciation.
Mutations can occur but separation or new mating partners can cause the most amount of speciation.
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