Evol Ecol Res 10: 537-558 (2008)     Full PDF if your library subscribes.

Differences in otolith morphologies between surface- and cave-dwelling populations of Poecilia mexicana (Teleostei, Poeciliidae) reflect adaptations to life in an extreme habitat

Tanja Schulz-Mirbach,1* Christoph Stransky,2 Jürgen Schlickeisen2 and Bettina Reichenbacher1

1Department of Earth and Environmental Sciences, Palaeontology, Ludwig-Maximilians-University Munich, Richard-Wagner-Str. 10, D-80333 Munich and  2Federal Research Centre for Fisheries, Institute for Sea Fisheries, Palmaille 9, D-22767 Hamburg, Germany

Author to whom all correspondence should be addressed.
e-mail: t.schulz-mirbach@lrz.uni-muenchen.de


Questions: Do otolith morphologies differ between surface- and cave-dwelling forms of Poecilia mexicana? Do otolith contours show differences between populations and do they display a morphological gradient from the cave outflow to the innermost cave chamber?

Organism: Surface- and cave-dwelling forms of a freshwater fish, the Atlantic molly (Poecilia mexicana).

Field sites: Two sites in the sulphidic cave system Cueva del Azufre in Tabasco, Southern Mexico, and two sites outside the cave – the cave outflow and a freshwater brook.

Methods: We analysed otolith morphology using scanning electron microscopy and otolith contours by Fourier shape analysis (N = 67).

Results: The otoliths of the cave form of P. mexicana are heavier and have a deeper sulcus (= furrow on the inner otolith face) than those of surface dwellers. Otolith contours show a morphological gradient that concurs with the morphocline of other traits (e.g. eye size).

Keywords: cave fish, hearing adaptation, morphocline, otolith, sulcus morphology.

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        © 2008 Tanja Schulz-Mirbach. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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