There is increasing emphasis on the importance of species populations, not species as a whole, in the evolutionary
process. Every species is made up of genetically or geographically distinct populations. Over time these populations
can diverge from each other, in specializing to a particular niche, and new sub-species and species can be formed.
A recent paper calculated that each species on average has 220 populations, giving a total of 1.1 to 6.6 billion
populations worldwide (assuming 5-30 million species on Earth). However, these populations are even more subject
to extinction than entire species because of their localities and small number of members. It is estimated that
in tropical forests alone, 1800 distinct populations are lost every hour, a rate of 16 million annually.
Continued: Rainforest diversity
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