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the process by which one species splits into 2 or more species
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-focal point of evolutionary theory because the appearance of new species is the source of biological diversity
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-it forms the bridge between microevolution and macroevolution
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impede mating or hinder fertilization if mating does occur
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- habitat isolation
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-temporal isolation
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-behavior isolation
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-mechanical isolation
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-gametic isolation
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-the time interval between speciation events varies considerable, from a few thousand years to tens of millions of years
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- punctuated equillibrium: isolated episodes of rapid speciation between long periods of little to no change
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gradualism: accumulation of gradual changes over time
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a group of populations whose members can interbreed in nature and produce viable, fertile offspring, but cannot produce viable, fertile offspring with other such groups
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barriers that prevent the hybrid zygote from developing into a viable, fertile adult
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-reduced hybrid viability
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-reduced hybrid fertility
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-hybrid breakdown
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Allopatric Speciation
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geographic barrier between the 2 populations
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Sympatric Speciation
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populations that live in the same geographic area
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-polyploidy
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-habitat differentiation
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-sexual selection
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reproductive isolation
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the existence of biological barriers that impede members of 2 species from interbreeding and producing viable offspring
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- speciation can occur in 2 main ways depending on how gene flow is interrupted between populations of the existing species
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- allopatric speciation-geographic isolation
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-sympatric speciation- no geographic isolation
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