BioLect8 - 1 1 Speciation 2 2 Odds & Ends 1....

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Unformatted text preview: 1 1 Speciation 2 2 Odds & Ends 1. Monday review 2. Wednesday Exam 3 Studying Speciation Ways to study speciation: 1) When and how do hybrid zones- regions in which members of different species meet and mate-occur? 2) What happens when allopatric populations/species come back together? Hybrids? No hybrids? 3) How does this compare to species that diverged sympatrically? Hybrids? No hybrids? 4 Fig. 24-14 Gene flow Population (five individuals are shown) Barrier to gene flow Hybrid Zones 2 5 Gene flow Population (five individuals are shown) Barrier to gene flow Isolated population diverges Fig. 24-14 6 Fig. 24-14-3 Gene flow Population (five individuals are shown) Barrier to gene flow Isolated population diverges Hybrid zone Hybrid Fig. 24-14 7 Fig. 24-14-4 Gene flow Population (five individuals are shown) Barrier to gene flow Isolated population diverges Hybrid zone Hybrid Possible outcomes: Reinforcement OR OR Fusion Stability 8 Reinforcement Reproductive barriers are strengthened If hybrids are less fit than parental species then individuals from each species will have HIGHER fitness if they do NOT mate with the other species And we expect natural selection to strengthen prezygotic reproductive barriers 2 5 Gene flow Population (five individuals are shown) Barrier to gene flow Isolated population diverges Fig. 24-14 6 Fig. 24-14-3 Gene flow Population (five individuals are shown) Barrier to gene flow Isolated population diverges Hybrid zone Hybrid Fig. 24-14 7 Fig. 24-14-4 Gene flow Population (five individuals are shown) Barrier to gene flow Isolated population diverges Hybrid zone Hybrid Possible outcomes: Reinforcement OR OR Fusion Stability 8 Reinforcement Reproductive barriers are strengthened If hybrids are less fit than parental species then individuals from each species will have HIGHER fitness if they do NOT mate with the other species And we expect natural selection to strengthen prezygotic reproductive barriers 3 9 Reinforcement...
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BioLect8 - 1 1 Speciation 2 2 Odds & Ends 1....

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