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Chapter 18.11. Other Speciation Models. AP Biology Spring 2011. Sympatric Speciation. Sympatric speciation : is divergence within the same home range of a species. Sympatric Speciation.
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Chapter 18.11 Other Speciation Models AP Biology Spring 2011
Sympatric Speciation • Sympatric speciation: is divergence within the same home range of a species
Sympatric Speciation • Polyploidy: is a result of nondisjunction during cell division that can lead to a change in chromosome number • Polyploidy can occur in plants • Nondisjunction occurs in a shoot or flower • If self-fertilization occurs, this can lead to instance speciation
Other Examples • Sympatric speciation can also occur to regional environmental conditions that force divergence • Ex. Soil pH and palm speciation • Fig. 18.23
Isolation at Hybrid Zones • Parapatric speciation: occurs when one population extends across a large diverse habitat • Distinct habitats exert selection pressures on parts of a population • Divergence occurs on the opposite ends of a habitat while a small hybrid zone exists where contact occurs in the midrange