slatkin3 - Bio 1B, Spring, 2008, Evolution section Lecture...

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Bio 1B, Spring, 2008, Evolution section 1 of 4 Updated 3/4/08 11:22 AM Lecture 3 3 Mendel, Hardy, and Weinberg Reading: 7th edition 454-458; 6 th edition 446-449 Response to the Origin Wide acceptance of the fact of evolution The publication of the Origin led to a scientific revolution. Most scientists quickly accepted Darwin’s claim that evolution had occurred. Disagreements about the pattern and mechanism There was and still is disagreement about the pattern and mechanism proposed by Darwin. Many of Darwin’s supporters did not agree with Darwin’s claim that the pattern was always gradual. They thought that discontinuous changes also occurred. They argued that the lack of intermediate forms was also consistent with discontinuous pattern of change. Part of the attraction of discontinuous change is that it is not necessary to explain what advantages intermediate forms had. For some characteristics, such as a the wing or a bird or pterosaur, it is difficult to know what advantage was conferred to an individual with a partially formed wing that is incapable of generating flight. Some supporters of Darwin’s theory thought that natural selection was not sufficient to cause all of evolution. Everyone agreed that that natural selection could cause changes in the way described in the Origin . The question was whether all changes in the history of life were caused by natural selection or whether additional mechanisms were needed. Mendel plus Darwin Darwin did not have a convincing explanation for inheritance The theory of natural selection was criticized because Darwin could not explain why differences among individuals persisted and how those differences are inherited. It appeared that natural selection would eliminate variation within species by eliminating less fit individuals. In later editions of the Origin , Darwin changed his discussion of inheritance, but he never effectively resolved this problem. Mendelian inheritance was rediscovered in 1900. Mendel, in 1865, discovered what is now called Mendelian inheritance, by studying characters in the common garden pea. His work was ignored at the time, but his achievements were later recognized when the same rules were rediscovered in 1900 and soon found to apply to a wide variety of plant and animal species, including humans. By the 1920s, there was general agreement that all of biological inheritance was
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This note was uploaded on 04/03/2008 for the course BIO 07853 taught by Professor Slatkin during the Spring '08 term at University of California, Berkeley.

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slatkin3 - Bio 1B, Spring, 2008, Evolution section Lecture...

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