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Published Online October 23, 2008
Science DOI: 10.1126/science.1162046

Reports

Submitted on June 19, 2008
Accepted on October 14, 2008

Variation in Evolutionary Patterns Across the Geographic Range of a Fossil Bivalve

Melissa Grey 1*, James W. Haggart 2, Paul L. Smith 1

1 Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
2 Geological Survey of Canada, 625 Robson St., Vancouver, British Columbia V6B 5J3, Canada.; Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.

* To whom correspondence should be addressed.
Melissa Grey , E-mail: mgrey{at}eos.ubc.ca

The fossil record is the only direct source of data for studying modes (patterns) and rates of morphological change over long periods of time. Determining modes and rates is important for understanding macroevolutionary processes, but just how modes and rates can vary within a taxon, and why, remain largely unaddressed. We examined patterns of morphological change in the shell of the Mesozoic marine bivalve genus Buchia over its geographic and temporal range. Most modes conform to either random walks or stasis, and both modes and rates show variability between locations. For example, stasis is more commonly noted in deeper marine environments, while random walks occur more often at the highest paleolatitudes studied. These results indicate that the environment can play a significant role in shaping patterns of evolution.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Environmental change drove macroevolution in cupuladriid bryozoans.
A. O'Dea and J. Jackson (2009)
Proc R Soc B 276, 3629-3634
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Science. ISSN 0036-8075 (print), 1095-9203 (online)