16.3+Speciation

Isolating Mechanisms: Reproductive Isolation Behavioral Isolation Geographic Isolation Temporal Isolation

=** Speciation in Darwin's Finches **= Finches from South America got blown over to the Gallapagos Islands. Through founding a new population, geogaphic isolation, changes in the new population's gene pool, reporoductive isolation and egological isolation thirteen new finches where created.

**__A) Founders Arrive__** xx []
 * 1) Species A is pushed by wind or storm to the Galapagos Islands from the mainland of South America.
 * 2) Since naturally these birds do not fly long distances they are stuck on the Islands.
 * 3) They manage to survive and reproduce
 * This isolation separates their gene pool from those on the mainland
 * They must adapt to the new enviroment

**__B) Geographic Isolation__**  **__ D) Reproductive Isolation __**
 * 1) Some birds from Species A fly to a new island.
 * 2) If these birds do not fly back their gene pool will be separated from Species A on Island 1.
 * __C) Changes in the Gene Pool__**
 * 1) On the second island there are larger, thick shelled seeds. Having a large beak would make it easier to get food.
 * 2) Overtime, natural selection would have caused the birds on the second island to evolve, giving them larger beaks, forming a **second population. **
 * 3) [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/9/97/Darwin%27s_finches.jpeg/220px-Darwin%27s_finches.jpeg width="154" height="143" caption="Large Ground-finch, Medium Ground-finch, Small Tree-finch, Warbler Finch" link="http://en.wikipedia.org/wiki/Darwin's_finches"]]


 * 1) Differences in beak sizes, combined with mating behavior led to the two population becoming separate species.
 * Finches choose their mates **carefully**, and part of this process is looking at a **potential mate's beak.**
 * Since the two populations have such different beaks, the chances of the two different populations mating together was **very slim.**

__**E) Ecological Competition**__
 * 1) As the two different species of finches live together on the same island, they must compete for the same seeds.
 * 2) The more different and specialized a bird is, the less competition it will have for certain kinds of food and seeds.
 * 3) Over time, the two species will evolve in a way that increases their differences.
 * This could possibly cause Species B to evolve into a new species, Species C.


 * __F) Continued Evolutions__ **
 * 1) The process of evolution that took places on these two islands probably took place all the way across the Galapagos Island Chain.
 * 2) This process has produced thirteen different species of finches.

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