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horse

horse. donkey. Speciation. mule. Speciation. Defined : evolution of a new species Species : group of organisms that can interbreed and produce fertile offspring Factors that lead to evolution Natural Selection Gene flow Mutations Sexual selection Genetic drift. Gene Flow (Migration).

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horse

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  1. horse donkey Speciation mule

  2. Speciation • Defined: evolution of a new species • Species: group of organisms that can interbreed and produce fertile offspring • Factors that lead to evolution • Natural Selection • Gene flow • Mutations • Sexual selection • Genetic drift

  3. Gene Flow(Migration) • Defined: Movement of alleles from 1 population to another • With gene flow: • At first: Increases variations in a population (new genes introduced) • Over time: Populations appear more similar (genes mix together) • If gene flow is prevented • Organisms adapt to their own environment • New species develop

  4. Reproductive Isolation • Small differences build up over time • New species develop • Occurs when gene flow is prevented by: • Geographic Isolation: • Organisms isolated by geographic barrier • Behavioral Isolation • Organisms isolated by differing mating rituals • Temporal Isolation • Organisms isolated by differing times of reproduction

  5. Kaibab Squirrel (Grand Canyon)

  6. Fruit flies of the same species were placed into two separate cages Famous fruit fly experiment Once isolated, the 2 groups were fed different types of food Although isolated, the flies continued to live and reproduce for many generations When brought back together most separated during reproduction.

  7. Birds of Paradise

  8. Genetic Drift • Defined: Changes in gene pool due to chance (not natural selection) • More likely in smaller populations • Ex: Natural disaster • Pre-forest fire (left picture): Blue is more advantageous • Post-forest fire (right picture): Due to more red survivors, red has the advantage to reproduce • Survival unrelated to adaptations

  9. Kobe Kuiz • What is speciation? • What leads to speciation? • What is gene flow? • What happens if gene flow is prevented? • How are temporal, behavioral, and geographic isolation different? • How are temporal, behavioral, and geographic isolation similar?

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