Patterns of maximum body size evolution in Cenozoic land mammals: Eco-evolutionary processes and abiotic forcing

Authors

Juha J. Saarinen, University of Helsinki, Helsinki, FinlandFollow
Alison G. Boyer, University of TennesseeFollow
James H. Brown, University of New Mexico
Daniel P. Costa, University of California, Santa CruzFollow
S.K. Morgan Ernest, Utah State University
Alistair R. Evans, Monash University, Victoria, AustraliaFollow
Mikael Fortelius, University of Helsinki, Helsinki, FinlandFollow
John L. Gittleman, University of GeorgiaFollow
Marcus J. Hamilton, University of New MexicoFollow
Larisa E, Harding, University of New Mexico
Kari Lintulaakso, University of Helsinki, Helsinki, FinlandFollow
S. Kathleen Lyons, University of Nebraska - LincolnFollow
Jordan G. Okie, University of New MexicoFollow
Richard M. Sibly, University of Reading, Reading, UKFollow
Patrick R. Stephens, University of GeorgiaFollow
Jessica Theodor, University of Calgary, AlbertaFollow
Mark D. Uhen, George Mason UniversityFollow
Felisa A. Smith, University of New MexicoFollow

Date of this Version

2014

Citation

Saarinen JJ et al. 2014 Patterns of maximum body size evolution in Cenozoic land mammals: eco-evolutionary processes and abiotic forcing. Proc. R. Soc. B 281: 20132049.

http://dx.doi.org/10.1098/rspb.2013.2049

Comments

Copyright 2014 The Authors. Published by the Royal Society. Used by permission.

Abstract

There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of individual clades. Here, we investigate the temporal distribution of maximum size observed within individual orders globally and on separate continents. While the maximum size of individual orders of large land mammals show differences and comprise several families, the times at which orders reach their maximum size over time show strong congruence, peaking in the Middle Eocene, the Oligocene and the Plio-Pleistocene. The Eocene peak occurs when global temperature and land mammal diversity are high and is best explained as a result of niche expansion rather than abiotic forcing. Since the Eocene, there is a significant correlation between maximum size frequency and global temperature proxy. The Oligocene peak is not statistically significant and may in part be due to sampling issues. The peak in the Plio-Pleistocene occurs when global temperature and land mammal diversity are low, it is statistically the most robust one and it is best explained by global cooling. We conclude that the macroevolutionary patterns observed are a result of the interplay between eco-evolutionary processes and abiotic forcing.