Lectures 22-24.Speciation Study Questions.2013

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Unformatted text preview: and E? a) 4 b) 6 c) 8 d) 3 e) 11 0 MILLIONS OF YEARS BEFORE PRESENT 2 4 A B C D E F G H I J BIS 2B, Spring 2013 Speciation Page 7 13. In apple maggot flies, Rhagoletis pomonella, adults and larvae feed on very specific host plants. There are at least three genetically distinct lineages, one of which specializes on hawthorn trees, another specializes on apples, and the third specializes on cherries. They are pretty good fliers, easily capable of moving several kilometers a day. They can also mate with each other, and the hybrids are fertile. In the example shown below, there are only apple or hawthorn trees available for the maggot flies. Assume that apple spets feed and mate primarily on apples, and that hawthorn spets feed and mate primarily on hawthorn fruits. (Sometimes, though, if it were available, an apple spet might feed on a hawthorn, and a hawthorn spet might feed on an apple.) Adult flies emerge a few weeks before their preferred fruit matures, fly around for awhile, then lay eggs on their preferred host (where their larvae feed and develop). What are the main barriers to gene flow between these two races? What, if any, is the importance of timing of fruit maturation in this scenario? How would you expect changes in timing of fruit maturation to affect the likelihood that hybrids would be formed? Assume that the apple and hawthorn races were good biological species? How could you distinguish whether they speciated sympatrically or allopatrically? 50% HAWTHORN RACE APPLE RACE % ADULT FLIES EMERGING apples mature hawthorns mature 0% 15 June 5 25 July 15 August 5 25 September 15 October 25 BIS 2B, Spring 2013 Speciation Page 8...
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This document was uploaded on 01/06/2014.

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