Assessing the role of cladogenesis in macroevolution by integrating fossil and molecular evidence
Luke C. Strotz1 and Andrew P. Allen
Author Affiliations
Department of Biological Sciences, Faculty of Science, Macquarie University, Sydney, NSW 2109, Australia
Edited by David Jablonski, University of Chicago, Chicago, IL, and approved November 18, 2012 (received for review May 16, 2012)
Abstract
Assessing the extent to which population subdivision during cladogenesis is necessary for long-term phenotypic evolution is of fundamental importance in a broad range of biological disciplines. Differentiating cladogenesis from anagenesis, defined as evolution within a species, has generally been hampered by dating precision, insufficient fossil data, and difficulties in establishing a direct link between morphological changes detectable in the fossil record and biological species. Here we quantify the relative frequencies of cladogenesis and anagenesis for macroperforate planktic Foraminifera, which arguably have the most complete fossil record currently available, to address this question. Analyzing this record in light of molecular evidence, while taking into account the precision of fossil dating techniques, we estimate that the fraction of speciation events attributable to anagenesis is <19 23="" 65="" and="" cenozoic="" during="" era="" font="" last="" myr="" neogene="" period="" the=""> Our central conclusion—that cladogenesis is the predominant mode by which new planktic Foraminifera taxa become established at macroevolutionary time scales—differs markedly from the conclusion reached in a recent study based solely on fossil data. These disparate findings demonstrate that interpretations of macroevolutionary dynamics in the fossil record can be fundamentally altered in light of genetic evidence.
punctuated equilibrium phyletic gradualism lineage morphospecies
Footnotes
1To whom correspondence should be addressed. E-mail: luke.strotz@mq.edu.au.
Author contributions: L.C.S. and A.P.A. designed research, performed research, analyzed data, and wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1208302110/-/DCSupplemental.
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