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Unformatted text preview: iming.
reproductive Courtship behavior is an example of a
behavioral Mechanical isolation: Female and male sex
organs or gametes are not compatible
Gametic isolation: After copulation, gametes
do not unite to form a zygote
do • Postzygotic barriers operate after hybrid zygotes are
formed Hybrid inviability: Hybrids do not survive Hybrid sterility: Hybrid offspring between two
species are sterile and therefore cannot mate
species Hybrid breakdown: Hybrids that mate with each
other or either parent species produce feeble or
Horse Donkey Mule - sterile MECHANISMS OF SPECIATION
MECHANISMS Geographic isolation can lead to speciation In allopatric speciation, a population is
• Barriers include geologic processes such as
emergence of a mountain or subsidence of a lake
• Changes in allele frequencies are unaffected by gene
flow from other populations
• New species often evolve, but only after reproductive
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This document was uploaded on 02/26/2014 for the course ENG 102 at Maryland.
- Spring '12