Paleobiology; January 2008; v. 34; no. 1;
p. 1-21; DOI: 10.1666/07026.1
© 2008 Paleontological Society
Predation defeats competition on the seafloor
Steven M. Stanley1
1 Department of Geology and Geophysics, University of Hawaii, 701 POST Building, 1680 East-West Road, Honolulu, Hawai‘i 96822. stevenst@hawaii.edu
Accepted 26 August 2007
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... the snail, whose tender horns being hit
Shrinks backward in his shelly cave with pain,
And there, all smothered up, in shade doth sit,
Long after fearing to creep forth again. ...
— William Shakespeare, Venus and Adonis (1593)
For many decades, ecology textbooks presented classical competition theory without reservation. The central principle here is that two species sharing an essential resource that is in limited supply cannot coexist for long because the competitively superior species will eliminate the other one. The implication is that ecological communities should be characterized by division of resources among species, or niche partitioning. Thus, it is understandable that many paleontologists have continued to invoke concepts of competitive exclusion and niche partitioning in their studies of ancient guilds and communities. By now, however, there is a large body of neontological literature demonstrating that interspecific competition and resource partitioning play only a minor role in many ecological communities— especially benthic marine communities, which are the primary focus of the following discussion. Predation and physical disturbance inflict so much damage on biotas of the seafloor that populations of one species seldom monopolize a potentially limiting resource, except sporadically and locally. As a result, it is uncommon for any species to drive another to extinction through competitive exclusion—or even to force another species to drastically change its exploitation of any environmental resource throughout its geographic range. Furthermore, what particular species or group of species occupies a particular microhabitat is often simply a matter of time of arrival.
The present contribution follows a memoir (Stanley 2007) showing that the taxonomic diversification of the large groups of marine taxa that Sepkoski (1981) identified as the Paleozoic and Modern faunas has entailed intervals of unbridled exponential increase separated by episodic mass extinctions. On this largest biotic scale, it is evident . . . [Full Text of this Article]
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The Lessons of Benthic Marine Ecology
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The Key Roles of Predation, Physical Disturbance, and Haphazard Recruitment
Weak Partitioning of Food Resources among Herbivores
Food Partitioning among Some Carnivores
The Role of Physical Disturbance
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The History of the Concept of Niche Partitioning
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Problematical Invocations of Competition in Marine Paleobiology
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The Structure of Ancient Benthic Marine Communities
The Idea of a Regional Carrying Capacity
The Idea of a Global Carrying Capacity
The Idea of a Dynamic Global Carrying Capacity Governed by Abiotic Factors
Exponential Increase for Individual Higher Taxa
Dubious Allegations of Displacement of One Higher Taxon by Another
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Possible Exceptions to the Rule of Weak Competition
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Proterozoic Phytoplankton
Cenozoic Barnacles
Encrusting Bryozoans
Cryptic Habits of Modern "Sclerosponges"
Niche Separation among Stalked Crinoids
The Issue of Long Time Scales
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Intensification of Predation over Phanerozoic Time
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How Has Biological Disturbance of Sediment Changed through Time?
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Weak Niche Partitioning and Low Rates of Speciation in the Ocean
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Survival of Incipient Species
An Advantage of Having Nonplanktonic Larvae
The Importance of Predator Avoidance and Fecundity
Conus: A Marine Snail Genus That Resembles Terrestrial Taxa in Ecology and Rate of Speciation
Carnivory and High Rates of Speciation for the Ammonoids
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Discussion
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Copyright © 2008 by Paleontological Society
