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Geography of Speciation

Geography of Speciation. Allopatric Peripatric Parapatric Sympatric. Fig. 24-6. Sister species in allopatry. A. harrisi. A. leucurus. Peripatric Speciation (like allopatric , but offers drift a bigger role). Divergent natural selection &/or Genetic Drift = Speciation.

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Geography of Speciation

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  1. Geography of Speciation • Allopatric • Peripatric • Parapatric • Sympatric

  2. Fig. 24-6 Sister species in allopatry A. harrisi A. leucurus

  3. Peripatric Speciation(like allopatric, but offers drift a bigger role) Divergent natural selection &/or Genetic Drift = Speciation Divergent natural selection &/or Genetic Drift = Speciation

  4. Sympatric and Parapatric Speciation • What do we mean by sympatry or parapatry? • In same geographic area (or side-by-side)? • Exchanging gene flow during the speciation process? • How finely should we divide the environment? • Habitat isolation in the same geographic area = real sympatry?

  5. Apple maggot flySympatric or Micro-allopatric? Pre-mating RIM = host fidelity Post-mating RIM =  scent tracking in F1’s http://evolution.berkeley.edu/evosite/evo101/VC1eSympatric.shtml

  6. Parapatric Speciation (sympatric, micro-allopatric?) Mine from mid-1800’s Contamination prevents most plant growth Strong, disruptive selection against interbreeding Different flowering times Anthoxanthumodoratum

  7. Mine soils (black): Flowering is earlier (flowers more developed in a point sample) Antonovics, Heredity (2006) 97, 33–37. doi:10.1038/sj.hdy.6800835

  8. Flowering stage along a transect from mine  field (border = dashed line) • Common garden experiment included • Trend persists over 40 years • 40% less mating between forms

  9. Parapatry, sympatry, or micro-allopatry?

  10. Mechanisms of Speciation • Mutation • Drift • Ecological Speciation (Driven by natural selection) • Sexual Selection

  11. Allopatric Speciation--Mutation http://evolution.berkeley.edu/evosite/history/modsynth2.shtml

  12. Gene Duplication is common • LOF mutation is common • Fixation of alternate mutations can  hybrid inviability

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