Darwin spent time on the Galápagos Islands collecting lots of specimens. Part of
ID: 187469 • Letter: D
Question
Darwin spent time on the Galápagos Islands collecting lots of specimens. Part of his collection was a variety of birds: blackbirds, grosbeaks, finches, and wrens. After a professional ornithologist studied the samples, Darwin learned that he did not have a wide variety of birds, just a bunch of finches that had evolved to resemble other kinds of birds. It is thought that the finch population on the islands originally came from South America and spread over millions of years across the different islands (see image below).
Describe the kind of speciation likely to have taken place and support your decision with details about possible mechanisms. How would you expect this speciation process to differ if birds regularly moved from South America to the islands?
20 - Number of islands -Number of finch species 15 10 0 Millions of years ago Biology: How Life Works, Second Edition 2016 W.H. Freeman and CompanyExplanation / Answer
Depending on the graph we can say that the distance between the islands allowed the finches to migrate however if we look at the time span we can say that this distance prevented any kind of interbreeding amongst these species thereby allowing them to evolve independently. This is called allopatric speciation.
If the birds regularly moved to the islands, then there is a good chance of them intebreeding thereby preventing the development of unique characteristics. Thus the process of speciation would be very slow.
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