2009 Portland GSA Annual Meeting (18-21 October 2009)
Paper No. 196-1
Presentation Time: 1:30 PM-1:45 PM

NO GENERAL RELATIONSHIP BETWEEN BODY SIZE AND EXTINCTION RISK IN THE FOSSIL RECORD OF MARINE INVERTEBRATES AND PHYTOPLANKTON

FINNEGAN, Seth1, WANG, Steve C.2, BOYER, Alison G.3, CLAPHAM, Matthew E.4, FINKEL, Zoe V.5, KOSNIK, Matthew A.6, KOWALEWSKI, Michal7, KRAUSE, Richard A. Jr8, LYONS, S. Kathleen9, MCCLAIN, Craig R.10, MCSHEA, Dan11, NOVACK-GOTTSHALL, Philip M.12, LOCKWOOD, Rowan13, PAYNE, Jonathan L.14, SMITH, Felisa15, SPAETH, Paula A.10, and STEMPIEN, Jennifer A.16, (1) Division of Geological and Planetry Sciences, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, sethf@caltech.edu, (2) Mathematics and Statistics, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, (3) Ecology, Behavior and Evolution Section, Univ. California- San Diego, 9500 Gilman Dr, MC 0116, La Jolla, CA 92093, (4) Department of Earth and Planetary Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, (5) Environmental Science Program, Mount Allison University, 314 Avard Dixon, Sackville, NB E4L 1G7, Canada, (6) Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia, (7) Florida Museum of Natural History, University of Florida, 1659 Museum Road, PO Box 117800, Gainesville, FL 32611, (8) Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06520, (9) Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, Washington, DC 20013, (10) National Evolutionary Synthesis Center, 2024 W. Main Street, Suite A200, Durham, NC 27705, (11) Department of Biology, Duke University, Durham, NC 27708, (12) Department of Biological Sciences, Benedictine University, Lisle, IL 60532, (13) Department of Geology, College of William and Mary, P.O. Box 8795, Williamsburg, VA 23187, (14) Dept. of Geological & Environmental Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, (15) Biology, University of New Mexico, MSC 03-2020, 1 University of New Mexico, Albuquerque, NM 87131, (16) Department of Geological Sciences, University of Colorado at Boulder, 2200 Colorado Ave, Boulder, CO 80309

Large body size is frequently cited as a general correlate of extinction risk, but empirical support for this association comes primarily from Quaternary-recent terrestrial vertebrates. It is unclear whether extinction risk is similarly size-biased in other taxa. We conducted a comprehensive examination of the association between body size and extinction risk for a phylogenetically and ecologically broad range of benthic invertebrate and planktonic groups through the Phanerozoic. In none of the groups examined did we find a consistent linear or nonlinear positive relationship between size and extinction risk (e.g., larger species experience higher extinction risk), either for the clade as a whole or among subtaxa within clades. One major group (gastropods) exhibits a weak but marginally significant inverse association between size and extinction risk that is consistent with findings from some previous studies, but taphonomic or collecting biases cannot be ruled out as the source of this relationship. Although other groups show occasional evidence of size-selective extinction at different times, these instances are uncommon and include approximately equal numbers of positive and inverse size-risk associations. Our results demonstrate that selective extinction of large-bodied taxa cannot be considered the normal macroevolutionary regime for marine invertebrates; limited evidence for such a bias in the modern is likely indicative of anthropogenic stresses. Selective extinctions of large species in other taxa during the Quaternary-recent may reflect ecological and life-history differences between these taxa and marine invertebrates, but may also be in part attributable to human impacts.

2009 Portland GSA Annual Meeting (18-21 October 2009)
General Information for this Meeting
Session No. 196
Paleontology: Macroevolution & Macroecology
Oregon Convention Center: Portland Ballroom 256
1:30 PM-5:30 PM, Tuesday, 20 October 2009

Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 506

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