macroecology
A bold paper by Rob Dunn et al in Ecology Letters is making news this month.  Dunn and an impressive list of coauthors pool observations of ant species richness from more than 1000 sites worldwide, finding that southern hemisphere habitats consistently support more species than their equivalents in the northern hemisphere. The pattern appears to be predicted primarily, but not entirely, by climate.
These results strike me as intuitively correct, and I suspect anyone who has collected ants in both hemispheres will agree. Brazil's fauna is spectacularly rich. That of Oklahoma, less so…