The maximum rate of mammal evolution

Alistair R. Evansa, David Jones, Alison G. Boyer, James H. Brown, Daniel P. Costa, S. K.Morgan Ernest, Erich M.G. Fitzgerald, Mikael Fortelius, John L. Gittleman, Marcus J. Hamilton, Larisa E. Harding, Kari Lintulaakso, S. Kathleen Lyons, Jordan Okie, Juha J. Saarinen, Richard M. Sibly, Felisa A. Smith, Patrick R. Stephens, Jessica M. Theodor, Mark D. Uhen

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

How fast can a mammal evolve from the size of a mouse to the size of an elephant? Achieving such a large transformation calls for major biological reorganization. Thus, the speed at which this occurs has important implications for extensive faunal changes, including adaptive radiations and recovery from mass extinctions. To quantify the pace of large-scale evolution we developed a metric, clade maximum rate, which represents the maximum evolutionary rate of a trait within a clade. We applied this metric to body mass evolution in mammals over the last 70 million years, during which multiple large evolutionary transitions occurred in oceans and on continents and islands. Our computations suggest that it took a minimum of 1.6, 5.1, and 10 million generations for terrestrial mammal mass to increase 100-, and 1,000-, and 5,000- fold, respectively. Values for whales were down to half the length (i.e., 1.1, 3, and 5 million generations), perhaps due to the reduced mechanical constraints of living in an aquatic environment. When differences in generation time are considered, we find an exponential increase in maximum mammal body mass during the 35 million years following the Cretaceous-Paleogene (K-Pg) extinction event. Our results also indicate a basic asymmetry in macroevolution: very large decreases (such as extreme insular dwarfism) can happen at more than 10 times the rate of increases. Our findings allow more rigorous comparisons of microevolutionary and macroevolutionary patterns and processes.

Original languageEnglish (US)
Pages (from-to)4187-4190
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number11
DOIs
StatePublished - Mar 13 2012

    Fingerprint

Keywords

  • Biological time
  • Haldanes
  • Pedomorphosis
  • Scaling

ASJC Scopus subject areas

  • General

Cite this

Evansa, A. R., Jones, D., Boyer, A. G., Brown, J. H., Costa, D. P., Ernest, S. K. M., Fitzgerald, E. M. G., Fortelius, M., Gittleman, J. L., Hamilton, M. J., Harding, L. E., Lintulaakso, K., Lyons, S. K., Okie, J., Saarinen, J. J., Sibly, R. M., Smith, F. A., Stephens, P. R., Theodor, J. M., & Uhen, M. D. (2012). The maximum rate of mammal evolution. Proceedings of the National Academy of Sciences of the United States of America, 109(11), 4187-4190. https://doi.org/10.1073/pnas.1120774109