The latitudinal gradient in recent speciation and extinction rates of birds and mammals.
Although the tropics harbor greater numbers of species than do temperate zones, it is not known whether the rates of speciation and extinction also follow a latitudinal gradient. By sampling birds and mammals, we found that the distribution of the evolutionary ages of sister species-pairs of species in which each is the other's closest relative-adheres to a latitudinal gradient. The time to divergence for sister species is shorter at high latitudes and longer in the tropics. Birth-death models fitting these data estimate that the highest recent speciation and extinction rates occur at high latitudes and decline toward the tropics. These results conflict with the prevailing view that links high tropical diversity to elevated tropical speciation rates. Instead, our findings suggest that faster turnover at high latitudes contributes to the latitudinal diversity gradient.
Weir
Jason T
JT
Biodiversity Research Center and Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. weir@zoology.ubc.ca
Schluter
Dolph
D
D000818:Animals; D044822:Biodiversity; D001717:Birds / Q000145:classification / Q000235:genetics; D045303:Cytochromes b / Q000235:genetics; D053476:Extinction, Biological; D049810:Genetic Speciation; D005843:Geography; D006239:Haplotypes; D016013:Likelihood Functions; D008322:Mammals / Q000145:classification / Q000235:genetics; D010802:Phylogeny; D014329:Tropical Climate
D045303:Cytochromes b