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| Unit 7: Demos |
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History
of Darwinism Evolution is a Fact and a Theory (talkorigins.org) Polymorphisms and genetic variability (4a) Sexual
dimorphism (10c) Divergent
evolution Barcoding Life: A New
Approach to Defining Species. |
Patterns of evolutionary change We can distinguish between two basic patterns of evolutionary change: anagenesis and cladogenesis (see Figure). Anagenesis, also called phyletic evolution, is the accumulation of changes that gradually transform a given species into a species with different characteristics. Cladogenesis, also called branching evolution, is the splitting of a gene pool into two or more separate pools, which each give rise to one or more new species. In cladogenesis, the parent species may change as well. Only cladogenesis can promote biological diversity by increasing the number of species. 
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