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Cope’s rule in the evolution of marine animals



Ben Creisler
bcreisler@gmail.com

A new paper that may be of interest:



Noel A. Heim, Matthew L. Knope, Ellen K. Schaal, Steve C. Wang, and
Jonathan L. Payne (2015)
Cope’s rule in the evolution of marine animals.
Science  347 (6224): 867-870
DOI: 10.1126/science.1260065: 867-870
http://www.sciencemag.org/content/347/6224/867.abstract

Cope’s rule proposes that animal lineages evolve toward larger body
size over time. To test this hypothesis across all marine animals, we
compiled a data set of body sizes for 17,208 genera of marine animals
spanning the past 542 million years. Mean biovolume across genera has
increased by a factor of 150 since the Cambrian, whereas minimum
biovolume has decreased by less than a factor of 10, and maximum
biovolume has increased by more than a factor of 100,000. Neutral
drift from a small initial value cannot explain this pattern. Instead,
most of the size increase reflects differential diversification across
classes, indicating that the pattern does not reflect a simple
scaling-up of widespread and persistent selection for larger size
within populations.

Press release:

http://news.stanford.edu/news/2015/february/body-size-evolution-021915.html