Understanding why some parts of the world sustain more species than others is one of the most enigmatic problems in ecology. One particularly common pattern is a "hump-shaped" biodiversity gradient: ...
Letten, Andrew D., Lyons, Sara K., and Moles, Angela T. 2013. "The mid-domain effect: it's not just about space." Journal of Biogeography, 40, (11) 2017–2019. https ...