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Speciation

Speciation. How does a species evolve from preexisting species?. What is a Species?. Group of organisms that  look alike,  can interbreed, &  mate to produce fertile offspring in nature. What do you get when you breed a donkey and a horse?. A MULE!!!.

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Speciation

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  1. Speciation How does a species evolve from preexisting species?

  2. What is a Species? • Group of organisms that look alike, can interbreed, & mate to produce fertile offspring in nature

  3. What do you get when you breed a donkey and a horse? A MULE!!! Does the mule fit the definition of a species?

  4. Why does a MULE NOT fit the definition of a species?? • Can interbreed XProduce fertile offspring • Do so in nature

  5. What do get when you breed a tiger and a lion? A LIGER!!! Does the liger fit the definition of a species?

  6. Why does a LIGER NOT fit the definition of a species?? • Can interbreed XProduce fertile offspring XDo so in nature

  7. Speciation = evolution of a new species • Happens b/c reproductive isolation • 3 ways

  8. 1. Behavioral Isolation • B/C different courtship rituals or other reproductive behaviors, like bird calls/songs • Ex. Eastern & Western Meadowlark

  9. 2. Geographical Isolation • When physical barriers (mountains, rivers, highways) separate populations • Ex: Grand Canyon squirrels, Darwin’s finches

  10. 3. Temporal Isolation • B/C pops reproduce @ different times • Ex. species of orchids & frogs

  11. Speciation can occur slowly or quickly 2 theories

  12. Gradualism • Species originate through a slow, steady change in adaptations • Proposed by Darwin • Supported by the fossil record

  13. Punctuated Equilibrium • Speciation occurs quickly in rapid bursts, with long periods of stability • Caused by environmental changes (ex. 3 isolations) • Supported by fossil record

  14. Species will diversify when introduced to a new environment or become extinct. 2 Patterns of Macroevolution

  15. 1. Divergent Evolution(adaptive radiation) • When species evolves into diverse new species • B/c different environments • Have homologous structures • Ex: polar vs. brown bear, Hawaiian honeycreeper

  16. 2. Convergent Evolution • Distantly related (or unrelated) organisms evolve similar traits • B/C similar environments • Have analogous structures

  17. Examples • Dolphin, penguin, fish - Streamlined shape b/c need to move thru water efficiently • Bird, bat, butterfly

  18. Extinctions: • 1. Background extinction - normal extinction rate, species that go extinct simply because not all life can be sustained on Earth and some species simply cannot survive. 2. Mass extinction  - widespread event that wipes out the majority (over 50%) of living plants and animals.

  19. Coevolution - the process by which two or more interacting species evolve together, each changing as a result of changes in the other or others • Beneficial relationships • ex. Acacia plant and stinging ant • Competitive relationships • Crabs and murex snails • Evolutionary arms race newt & snake 2:20-8:26min https://www.youtube.com/watch?v=iTjkSDaXF7s

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