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Marine Ecology Progress Series

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MEPS 357:283-289 (2008)  -  DOI:

Stable isotope analysis of the Hypoplectrus species complex reveals no evidence for dietary niche divergence

Ben G. Holt1,*, Brent C. Emerson1, J. Newton2, Matthew J. G. Gage1, Isabelle M. Côté3

1School of Biological Sciences, University of East Anglia, Norwich NR7 4TJ, UK
2NERC Life Sciences Mass Spectrometry Facility, Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride G75 0QF, UK
3Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

ABSTRACT: The polymorphic coral reef fish genus Hypoplectrus (hamlets) provides an excellent system for examining the initial stages of natural biological divergence in the expansive marine environment. Despite close genetic similarities, hamlets occur in assortatively mating colour morphotypes. In this study, we determined whether ecological differences exist between morphs that could reinforce the assortative mating pattern within morphs. We compared the carbon and nitrogen stable isotope dietary signatures of 6 hamlet morphotypes from 5 geographically distant locations. Across 364 individuals, and with the exception of fish sampled in the Gulf of Mexico, no significant isotopic associations with morphotype were detected. Our results therefore provide no evidence that different hamlet morphs are associated with distinct dietary niches, despite finding highly significant geographical differentiation for both isotopes. We argue that tight assortative mating without ecological divergence could be maintained through the demands of reciprocal cooperation within a reproductive pattern of simultaneous hermaphroditism which characterises all hamlets.

KEY WORDS: Caribbean · Dietary niche · Hamlets · Marine adaptive radiation · Colour polymorphism

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Cite this article as: Holt BG, Emerson BC, Newton J, Gage MJG, Côté IM (2008) Stable isotope analysis of the Hypoplectrus species complex reveals no evidence for dietary niche divergence. Mar Ecol Prog Ser 357:283-289.

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