The number of recognized mammal species has increased over time from 4,631 species in 1993 to 5,416 in 2005, and now to 6,495 species. This total includes 96 species extinct within the last 500 years, and represents nearly a 20% increase in overall mammal diversity. The updated tabulation details 1,251 new species recognitions, at least 172 unions, and multiple major, higher-level changes, including an additional 88 genera and 14 newly recognized families. The new study documents a long-term global rate of about 25 species recognized per year, with the Neotropics (Central America, the Caribbean, and South America) as the region of greatest species density, followed closely by tropical regions of Africa, Asia, and the Indo-Pacific.
Previous sporadic releases of the Mammal Species of the World series, the latest edition of which was published in 2005, have resulted in the major time gap among estimates of mammal species number. Yet the continued steady flow of taxonomic changes proposed in peer-reviewed journals and books means that changes proposed more than a decade ago have yet to be incorporated centrally, until now. The lag between the publication and synthesis of research can hamper conservation efforts, since management decisions often depend upon the precise designation of distinctive animal populations.
“A big part of what we are aiming to do is centralize known information about mammal species diversity, and thereby democratize access to studying them,” said Nathan Upham, the study’s senior author and a postdoctoral researcher at Yale University. Paper. (public access) – Connor J Burgin, Jocelyn P Colella, Philip L Kahn, Nathan S Upham. How many species of mammals are there? Journal of Mammalogy, 2018; 99 (1): 1 DOI: 10.1093/mammal/gyx147 More.
If tabulating species just means noting when a researcher, working with a personal philosophy of classification (“lumpers” vs. “splitters”) has decided to call a type of mammal a new species, the researchers’ findings amount to a history of the trends in classification. What we need is a clear, science-based standard for determining when speciation has occurred. The fact that we don’t have it is part of the necrosis of Darwinism.
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