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Unformatted text preview: flow, with no
geographical isolation Figure 24.5 (Campbell et al 9th ed) 53 Cladogenesis via Allopatric Speciation 1. Geological processes isolate populations
Barrier = isolation
Harris’s squirrel Figure 24.6 (Campbell et al 9th ed) White-tailed squirrel 54 Allopatric speciation
of ratite bird species
via continental drift Cassowary American rhea Ostrich Elephant bird Emu Moa Kiwi 55 Cladogenesis via Allopatric Speciation 2. Colonization of new, geographically remote areas
isolates new pop from old pop.
Barrier = isolation 56 Cladogenesis via Allopatric Speciation 3. Extinction of connecting population
isolates 2 distant pops.
Barrier = isolation What happens when isolated populations
w/ incomplete reproductive barriers come into contact?
57 If not too different pops
interbreed and differences ↓
Further reproductive isolation
(Pre- or post-zygotic) of pops
so don’t waste energy making
Area where 2 spp interbreed.
Stable Hybrid Zone
Speciation via hybridization Depending if offspring survive
and extent of interbreed...
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