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When Darwin was observing the Galapagos finches he noticed that there was a different kind on each island. The biggest difference was in their beaks. Darwin concluded that the birds had evolved and the form of their beaks had changed because the available food was harder on some islands and less hard on others. Now we know of course that the alteration was possible due to mutations. Hardness of the food is not a mutagenic material (it isn't a material at all) so mutations should be random. If we look from the mathematical perspective of randomness the same event should occur in multiple places after some time. In this case the same mutations should occur on different islands after some time. But if that were true then there wouldn't have been just one kind of finches on the island with the least hard food. Natural selection would take care of the finches with small beaks on islands with hard food but finches with strong beaks wouldn't have a problem with small seeds so if they had ever existed on such island they would have survived. But Darwin never saw a finch with a big beak on an island full of small seeds. If my facts are wrong please tell me where I made a mistake otherwise can someone please explain to me how is this possible?

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put on hold as unclear what you're asking by Remi.b, David, James, theforestecologist, AliceD 20 hours ago

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ You profoundly misunderstand evolution, confusing the randomness of mutations with the non-randomness of natural selection. Your question contains many incorrect assumptions. I've voted to close as "Unclear what you're asking", since your incorrect premises make an unclear question. $\endgroup$ – iayork Jan 17 at 20:07
  • $\begingroup$ Your question is quite hard to understand. Are you asking Why are big beaks birds at a fitness disadvantage compared to small beak birds in environments with small seeds only?? $\endgroup$ – Remi.b Jan 17 at 20:17
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    $\begingroup$ @HinkoPihPih What if big beaks are more costly to grow/maintain or if big beaks are not as good for eating small seeds as small beaks? Why would a big beaked bird have any advantage if there is no food that requires the big beak? $\endgroup$ – Bryan Krause Jan 17 at 22:10
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    $\begingroup$ See this scientific report overview for a case of beak size selection being observed. $\endgroup$ – mgkrebbs Jan 17 at 23:49
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    $\begingroup$ So your question was actually "What is the selective disadvantage to large beaks in finches"? That's a perfectly good and answerable question. For future questions, try to avoid bringing in assumptions (e.g. your comments about mutations), because they turn a simple question into a loaded and unanswerable one. $\endgroup$ – iayork Jan 18 at 13:45