Part B-Character displacement in Galapagos ground finches The figure shows an ex
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Question
Part B-Character displacement in Galapagos ground finches The figure shows an example of character displacement in the Galapagos ground finches Geospiza fuliginosa (small ground finch) and Geospiza fortis (medium ground finch) The character, or trait, being displaced in this example is beak depth. Beak depth correlates with diet, so that finches with similar beak sizes eat similar food. The first two graphs show beak sizes in allopatric, or geographically separate, populations of G fuliginosa and G. fortis. The bottom graph shows beak sizes in sympatric populations, where the two species occur together. When character displacement has occurred, the traits of sympatic populations diverge more than the traits of allopatric populations. In other words, there is more overlap in the beak size of the allopatric finch populations (top two graphs) than in the sympatric finch populations (bottom graph). 60 Hermanos io Santa Maria, San Beni depth (mm) Fill in the sentences below, which explain how character displacement evolved in the finch populations on Santa Maria and San Cristobal islands. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used. 1. When the finches first colonized Santa Maria and San interspecific competition Cristobal, G. fuliginosa probably had beak sizes similar to finches on island, and G. fortis probably had shallower beaks beak sizes similar to finches on island deeper beaks 2. Significant overlap in beak size would have resulted in for food. 3. Natural selection favored phenotypes that competedExplanation / Answer
Answer
When the finches first colonized Santa Maria and San Cristobal, G.fuliginosa probably had beak sizes similar to finches on Los Hermanos island, and G. fortis probably had beak sizes similar to finches on Daphne island.
Significant overlap in beak size would have resulted in interspecific competition for food.
Natural selection favored phenotypes that competed less for food.
In G.fortis, finches with deeper beaks were selected for.
In G.fuliginosa, finches with shallower beaks were selected for.
Each species experienced directional selection, which resulted in character displacement for beak size.
Character displacement is adaptive for both populations because it reduces interspecific competition.