Present-day drivers do not explain biodiversity patterns in mammals

TLDR: The authors used checklists of medium and large mammals from across four zoogeographic realms: Afrotropical, Indomalayan, Malagasy (Madagascar), and Neotropical, to determine the relative importance of different factors in driving patterns of mammalian biodiversity across the tropics and subtropics.

Abstract: Mammals are an obvious choice for analyses of global biodiversity patterns. They are not too diverse, disproportionately well studied, and even nonspecialists will be interested in the results. They are also fairly good indicators of overall vertebrate diversity (1). Moreover, the limited ability of most mammals to cross oceanic barriers and the lack of direct land connections between the Neotropics (South and Central America), Africa, Madagascar, Asia, and Australasia (Australia and New Guinea) provide an opportunity to compare more or less independent evolutionary responses to similar tropical and subtropical environments (2). Such comparisons are complicated, however, by the widespread impacts of climate change and human activities over the last 100,000 y, from the Late Pleistocene megafaunal extinctions to the ongoing consequences of recent human population growth and economic development across the tropics (3). Understanding the reasons for the similarities and differences within and between regions is of more than just theoretical interest, since it may also have practical importance for conservation management. In PNAS, Rowan et al. (4) address this issue and attempt to determine the relative importance of different factors in driving patterns of mammalian biodiversity across the tropics and subtropics. They excluded smaller species (<500 g) from their analyses, greatly reducing the scale of the task, since most mammals are small rodents or bats, while greatly increasing the quality of the data available, since larger species are easier to find and study. They were then able to assemble an impressive dataset consisting of 515 checklists of medium and large mammals from across four zoogeographic realms: Afrotropical, Indomalayan, Malagasy (Madagascar), and Neotropical. They excluded tropical Australasia, presumably because there were too few complete checklists from this realm. The final dataset included 852 species, many of which are now under threat from hunting and/or habit loss. For each community, they … [↵][1]1Email: corlett{at}xtbg.org.cn. [1]: #xref-corresp-1-1