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Simulations of evolutionary radiations and their application to understanding the probability of a Cambrian explosion

Jeffrey Levinton, Lindsey Dubb and Gregory A. Wray
Simulations of evolutionary radiations and their application to understanding the probability of a Cambrian explosion (in When clocks collide; calibrating lineage divergences from fossils and molecules, Christopher A. Brochu (prefacer), Colin D. Sumrall (prefacer) and Jessica M. Theodor (prefacer))
Journal of Paleontology (January 2004) 78 (1): 31-38

Abstract

A molecular survey of animal phylogeny (Wray et al., 1996) recovered the presumed correct temporal order of the phylogenetic splits Protostomata-Deuterostomata, Echinodermata-Chordata, and Agnatha-Gnathostomata in studies of six of seven gene sequences. This result raised the question of how this order could be recovered if all of the phyla had appeared in a Cambrian "explosion" of less than 10 m.y., given the expected erratic nature of the molecular "clock." We simulated trees, and molecular sequence evolution along the trees, under different evolutionary radiation scenarios, with different periods of radiation, relative to times of subsequent evolution. Simulations and phylogenetic analyses of sequences derived from a simulated "Cambrian explosion" of 10-35 million years did not allow the successful recovery of the correct tree, using neighbor-joining, maximum likelihood, or parsimony methods. Success in recovering phylogenies under a Cambrian divergence scenario (520 million years ago) did not exceed 80 percent without an extended divergence time interval of at least 100 m.y. An increased substitution rate during the initial radiation improved the ability to recover correct phylogenies, especially when the rate was 8-10 times the rate following the radiation. Our results militate against the likelihood of an Early Cambrian or slightly longer explosion of the animal phyla, as apparently supported by the fossil record. Some limitations to these conclusions are discussed.


ISSN: 0022-3360
EISSN: 1937-2337
Coden: JPALAZ
Serial Title: Journal of Paleontology
Serial Volume: 78
Serial Issue: 1
Title: Simulations of evolutionary radiations and their application to understanding the probability of a Cambrian explosion
Title: When clocks collide; calibrating lineage divergences from fossils and molecules
Author(s): Levinton, JeffreyDubb, LindseyWray, Gregory A.
Author(s): Brochu, Christopher A.prefacer
Author(s): Sumrall, Colin D.prefacer
Author(s): Theodor, Jessica M.prefacer
Affiliation: State University of New York at Stony Brook, Department of Ecology and Evolution, Stony Brook, NY, United States
Affiliation: University of Iowa, Department of Geoscience, Iowa City, IA, United States
Pages: 31-38
Published: 200401
Text Language: English
Publisher: Paleontological Society, Lawrence, KS, United States
Meeting name: Sixth North American paleontological convention ; symposium on When clocks collide; calibrating lineage divergences from fossils and molecules
Meeting location: Washington, DC, USA, United States
Meeting date: 19960609June 9-12, 1996
References: 43
Accession Number: 2004-026468
Categories: General paleontology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: University of Tennessee, USA, United StatesIllinois State Museum, USA, United StatesUniversity of Washington, USA, United StatesDuke University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200408
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