28/12/2015 Abstract: SHOULD THE LONGTERM BIOTIC RESPONSES TO ENVIRONMENTAL CHANGES BE LINEAR/EXPONENTIAL?: PERSPECTIVES F…
Start |Author Index | View Uploaded Presentations | Meeting Information 2015 GSA Annual Meeting in Baltimore, Maryland, USA (14 November 2015) Paper No. 1813 Presentation Time: 11:30 AM
SHOULD THE LONGTERM BIOTIC RESPONSES TO ENVIRONMENTAL CHANGES BE LINEAR/EXPONENTIAL?: PERSPECTIVES FROM PLANKTIC FORAMINIFERA AND MARINE BIVALVES HARRIES, Peter J., Department of Marine, Earth, and Atmospheric Sciences, NC State University, 2800 Faucette Drive, Jordan Hall, Campus Box 8208, Raleigh, NC 276958208, CARDENAS, Andres L., Ciencias de la Terra, Universidad EAFIT, Carrera 49 No 7 sur 50, Medellin, Colombia and MONDAL, Subhronil, Department of Geology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, 700 019, India,
[email protected] Attempts to determine the role of environmental change in driving biotic responses has often been viewed through the lens that the expectation should be one of a linear or exponential process. This perspective has largely been driven by a desire to: (i) simplify incredible complexity and (ii) to have a level of prediction within biologic systems that has been fueled by a few wellestablished relationships as exemplified by the speciesarea effect. This expectation for a predictable response has, at least to a degree, resulted in an expectation that longterm environmental and biotic data, especially richness/diversity trends at various taxonomic levels, should correlate. Mismatches have been either ignored or attributed to various complications. Here, we examine this expectation using data compiled from two groups: the planktic Foraminifera as well as the benthic marine Bivalvia (Phylum Mollusca) and comparing them to various environmental proxies, including temperature and sea level. Our results suggest that initial phases in a clade’s diversification are driven largely by evolutionary controls and, therefore, the impact of various environmental factors is difficult to assess. This is followed by the adaptive radiation of the group (which occurred ~30 Ma and ~40 Ma after their initial appearance for foraminfers and bivalves, respectively). Once these groups reached relatively higher standing diversity levels, the overall climatic regime – the alternation between green and icehouse climates – appears to play a substantial role in regulating the biotic response. These intervals are associated with different types of controls on biotic diversification (i.e., changes in both oceanic stratification and in oceanic circulation patterns) which substantially disrupt a linear/exponential response. Instead, the various ‘tipping points’ that result in relatively rapid shifts from one climatic mode to another result in a range of variables which impact the biota in a nonlinear fashion. We suggest that the impact of dramatic shifts in richness/diversity across a broad spectrum of environmental proxies should be potentially reexamined from a nonlinearresponse perspective.
Session No. 18 T149. CoEvolution of Life and Planet: Broad–Scale Controls on Biodiversity I Sunday, 1 November 2015: 8:00 AM12:00 PM Room 314 (Baltimore Convention Center) Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.64 © Copyright 2015 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.
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