OCGC Seminar - The Roles of Climate and Biotic Interchange in the Assembly of Mammal Communities


Danielle Fraser 
Research Scientist, Paleobiology, 
Museum of Nature  

Thursday, March 16th 
11:30 a.m.
3120 HP 



The richness and species composition of mammal communities has changed vastly throughout the Cenozoic (66 Ma to present). My research program therefore focuses on testing for the relative effects of different drivers (i.e. climate change and species interactions) on mammalian diversity and morphological evolution. I show that mammalian latitudinal diversity gradients are weakest under the warmest and wettest Cenozoic conditions, when volumes of Arctic sea ice were lowest. I suggest that changes in the intensity of latitudinal climate gradients were responsible. I also show that the first appearance of Perissodactyla, primates, and Artiodactyla in North America led to an increase in the intensity of species interactions during the Paleocene-Eocene Thermal Maximum (~56 Ma). Despite significant dwarfing among mammals, the distribution of body sizes within communities did not change. Instead, North American mammals increased their partitioning of the landscape in response to intensified competition. I show that competitive interactions among species can be further parsed using detailed dietary reconstruction and comparative morphology. I demonstrate that both climate and species interactions have structured mammalian communities to varying degrees throughout mammalian evolutionary history.