RT Journal Article
SR Electronic
T1 The latitudinal gradient in rates of evolution for bird beaks, a species interaction trait
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.07.31.231142
DO 10.1101/2020.07.31.231142
A1 Freeman, Benjamin G
A1 Schluter, Dolph
A1 Tobias, Joseph A
YR 2020
UL http://biorxiv.org/content/early/2020/11/19/2020.07.31.231142.abstract
AB Where is evolution fastest? The biotic interactions hypothesis proposes that greater species richness creates more ecological opportunity, driving faster evolution at low latitudes, whereas the “empty niches” hypothesis proposes that ecological opportunity is greater where diversity is low, spurring faster evolution at high latitudes. Here we tested these contrasting predictions by analyzing rates of bird beak evolution for a global dataset of 1141 sister pairs of birds. Beak size evolves at similar rates across latitudes, while beak shape evolves faster in the temperate zone, consistent with the empty niches hypothesis. We show in a meta-analysis that trait evolution and recent speciation rates are faster in the temperate zone, while rates of molecular evolution are slightly faster in the tropics. Our results suggest that drivers of evolutionary diversification are more potent at higher latitudes, thus calling into question multiple hypotheses invoking faster tropical evolution to explain the latitudinal diversity gradient.Competing Interest StatementThe authors have declared no competing interest.