Geography of Speciation Allopatric Peripatric Parapatric Sympatric Fig

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

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 fly Sympatric or Micro-allopatric? Pre-mating RIM = host fidelity Post-mating RIM = scent tracking in F 1’s http: //evolution. berkeley. edu/evosite/evo 101/VC 1 e. Sympatric. sht ml

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

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/modsynth 2. shtml

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