Ch 25 - The history of life on earth (1 slide per page)-2

modified versions of older structures eg evolution

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Unformatted text preview: modifications 60 What Causes Adaptive Radiation? - Modified versions of older structures e.g. Evolution of mammalian jaw Figure 25.6 (Campbell 9th ed) 61 What Causes Adaptive Radiation? - Modified versions of older structures - Simple structures gradually evolved complexity e.g. eyes Refer to Figure 25.24 (Campbell 8th ed) 62 What Causes Adaptive Radiation? - Modified versions of older structures - existing biological structure or function used for a purpose other than that for which it initially evolved e.g. Scales to insulating feathers to flight feathers 65 What Causes Adaptive Radiation? 1. Ecological opportunity 2. New adaptations can lead to morphological innovation - How do new adaptations arise? - Modified versions of older structures - Developmental gene modifications 66 Developmental gene modifications 1. Changes in timing 2. Changes in spatial pattern 3. New genes and changes in genes Slight modifications can lead to: - major morphological differences - evolutionary change 67 Developmental gene modifications 1. Changes in timing • At what point a process starts/finishes • How long a process continues 68 Developmental gene modifications 1. Changes in timing – e.g. Paedomorphosis - Retention of juvenile characteristics humans vs. other primates Refer to Figure 25.21 (Campbell 9th ed) axolotl salamander 69 Developmental gene modifications 1. Changes in timing • genes switch off foot growth early • shorter digits and more webbing small genetic change can amplify into substantial morphological change 70 Developmental gene modifications 1. Changes in timing 2. Changes in spatial pattern –...
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This note was uploaded on 02/12/2014 for the course BIOLOGY 2011 taught by Professor Woo during the Fall '10 term at University of Central Florida.

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