Geography of Speciation
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Transcript of Geography of Speciation
Geography of Speciation
• Allopatric– Peripatric
• Parapatric• Sympatric
Fig. 24-6
A. harrisi A. leucurus
Sister species in allopatry
Peripatric Speciation(like allopatric, but offers drift a bigger role)
Divergent natural selection &/orGenetic Drift= Speciation
Divergent natural selection &/or
Genetic Drift= Speciation
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?
Apple maggot flySympatric or Micro-allopatric?
http://evolution.berkeley.edu/evosite/evo101/VC1eSympatric.shtml
Pre-mating RIM = host fidelityPost-mating RIM = scent tracking in F1’s
Parapatric Speciation (sympatric, micro-allopatric?)
Anthoxanthum odoratum
Mine from mid-1800’sContamination prevents most plant growthStrong, disruptive selection against interbreedingDifferent flowering times
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
• 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
• Parapatry, sympatry, or micro-allopatry?
Mechanisms of Speciation
• Mutation• Drift• Ecological Speciation (Driven by natural selection)• Sexual Selection
Allopatric Speciation--Mutation
http://evolution.berkeley.edu/evosite/history/modsynth2.shtml
•Gene Duplication is common•LOF mutation is common•Fixation of alternate mutations can hybrid inviability