2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM
Paper No. 285-9
Presentation Time: 10:30 AM-10:45 AM

Coping with Recovery: Community Sensitivity and Resistance in the Wake of Mass Extinction

ROOPNARINE, Peter D.1, WANG, Steve C.2, ANGIELCZYK, Kenneth D.3, and HERTOG, Rachel1, (1) Invertebrate Zoology & Geology, California Academy of Sciences, 55 Concourse Dr, Golden Gate Park, San Francisco, CA 94118, proopnarine@calacademy.org, (2) Mathematics and Statistics, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, (3) Department of Geology, The Field Museum, 1400 South Lake Shore Drive, Chicago, IL 60605

Mass extinctions represent the disturbance, and perhaps collapse, of ecosystems in response to intense perturbation. Ecosystem recovery in the wake of such events is dominated by the contingencies of survivorship and the opportunism of diversification. The question then arises of whether post-extinction recovery communities are subsets of their predecessors, and function similarly, or whether they are no-analog communities with new properties and comprising new biotic relationships. Our ongoing survey of marine and terrestrial communities spanning the Paleozoic to the Recent suggests that, during any typical time interval, community networks tend to be structured trophically so that the propagation of low intensity perturbations to species or sets of species, to other members of the community, is localized and minimal. Paleocomunities reconstructed from the Early Triassic Lystrosaurus Assemblage Zone of the Karoo Basin, however, differed significantly from preceding and successive paleocommunities with respect to such propagation. Lystrosaurus zone communities were potentially hypersensitive to disturbance, raising the questions of why and how could those communities have persisted during what was likely an environmentally unstable time. Preliminary data suggest that the sensitivity resulted from the low diversity of amniote herbivores and omnivores in the aftermath of the end-Permian extinction, and the resulting creation of long pathways in Early Triassic food webs. We explore the possibilities that these communities could have persisted because of above-average rates of evolution, and/or metapopulation structures that were capable of sustaining local populations in the face of high rates of extirpation. The transition to the Cynognathus Assemblage Zone by the late Early Triassic was marked by the recovery of amniote diversity, and a return to more resistant communities.

2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM
General Information for this Meeting
Session No. 285
Recoveries from Mass Extinction: Patterns, Processes, and Comparisons I
George R. Brown Convention Center: 320DE
8:00 AM-12:00 PM, Wednesday, 8 October 2008

Geological Society of America Abstracts with Programs, Vol. 40, No. 6, p. 436

© Copyright 2008 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.