The Latitudinal Gradient in Recent Speciation and Extinction Rates of Birds and Mammals

@article{Weir2007TheLG,
  title={The Latitudinal Gradient in Recent Speciation and Extinction Rates of Birds and Mammals},
  author={Jason T. Weir and Dolph Schluter},
  journal={Science},
  year={2007},
  volume={315},
  pages={1574 - 1576}
}
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… 
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