Sympatric speciation as a consequence of male pregnancy in seahorses
- †School of Biology, 310 Ferst Drive, Georgia Institute of Technology, Atlanta, GA 30332
- §Department of Zoology, University of Western Australia, Nedlands, Western Australia 6009, Australia
- ¶Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden
- ∥Department of Genetics, University of Georgia, Athens, GA 30602
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Contributed by John C. Avise, April 4, 2003
Abstract
The phenomenon of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) undeniably has sculpted the course of behavioral evolution in these fishes. Here we explore another potentially important but previously unrecognized consequence of male pregnancy: a predisposition for sympatric speciation. We present microsatellite data on genetic parentage that show that seahorses mate size-assortatively in nature. We then develop a quantitative genetic model based on these empirical findings to demonstrate that sympatric speciation indeed can occur under this mating regime in response to weak disruptive selection on body size. We also evaluate phylogenetic evidence bearing on sympatric speciation by asking whether tiny seahorse species are sister taxa to large sympatric relatives. Overall, our results indicate that sympatric speciation is a plausible mechanism for the diversification of seahorses, and that assortative mating (in this case as a result of male parental care) may warrant broader attention in the speciation process for some other taxonomic groups as well.
Footnotes
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↵ ‡ To whom correspondence should be addressed at: School of Biology, 310 Ferst Drive, Georgia Institute of Technology, Atlanta, GA 30332. E-mail: adam.jones{at}biology.gatech.edu.
- Copyright © 2003, The National Academy of Sciences
