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17.3 Speciation

17.3 Speciation. WESTERN and EASTERN MEADOWLARK Different Mating Calls. Last Ice Age 110,000 to 10,000 years ago. Species - a population whose members can interbreed and produce fertile offspring. Speciation - the formation of a new species. KAIBAB Squirrel.

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17.3 Speciation

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  1. 17.3 Speciation WESTERN and EASTERN MEADOWLARK Different Mating Calls

  2. Last Ice Age 110,000 to 10,000 years ago

  3. Species - a population whose members can interbreed and produce fertile offspring

  4. Speciation - the formation of a new species KAIBAB Squirrel

  5. Reproductive Isolation (3)- when one species evolves into two separate species that cannot interbreed

  6. Behavioral Isolation - different behaviors affect sexual selection (like mating calls) - can be mechanical also: snails species with opposite spirals can’t mate

  7. 2) Geographic Isolation - physical barrier separates population and gene pools diverge

  8. Temporal Isolation - when different species reproduce at different times Ex) 13 and 17 year cicadas (do they ever meet?)

  9. Practice Quiz • A small amount of finches migrate from South America to the Galapagos Islands, where there are no other finches. This is an example of: • Genetic drift • Founder’s Effect • Genetic equilibrium • Behavioral isolation

  10. The kaibab squirrels of the Southwest got separated from the rest of the squirrel population by the Grand Canyon and eventually formed their own species. This is: • Behavioral isolation • Temporal isolation • Geographical isolation • Pure luck

  11. Genetic equilibrium means: • The species’ gene pool is rapidly changing • Only the strong reproduce • The species is pressured by natural selection • The specie’s gene pool is barely changing

  12. 4) A population will be in genetic equilibrium unless: a) the population is large b) there is no immigration or emigration c) random mutations are minimal d) environmental pressure is creating natural selection

  13. 5) Which type of natural selection favors organisms near the mean (middle range) for the trait? a) Directional b) Stabilizing c) Disruptive

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