key concept 22.5 Speciation Rates Are Highly Variable across Life

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Many factors influence the likelihood that a lineage will split to form two or more species. Therefore rates of speciation (the proportion of existing species that split to form new species over a given period) vary greatly among groups of organisms. What are some of the factors that influence the probability of a given lineage splitting into two?

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  • Speciation rates vary for different groups of organisms, due to several ecological and behavioral factors.

  • The availability of unoccupied ecological niches increases the likelihood of adaptive radiation following colonization by a founder species.