Abstract
Inter-population differences in otolith shape, morphology and chemistry have been used effectively as indicators for stock assessment or for recognizing environmental adaptation in fishes. However, the precise parameters that affect otolith morphology remain incompletely understood. Here we provide the first direct support for the hypothesis that inter-population differences in otolith morphology are genetically encoded. The study is based on otolith morphology and two mitochondrial markers (D-loop, 16S rRNA) of three natural populations of Aphanius fasciatus (Teleostei: Cyprinodontidae) from Southeast Tunisia. Otolith and genetic data yielded congruent tree topologies. Divergence of populations likely results from isolation events in the course of the Pleistocene sea level drops. We propose that otolith morphology is a valuable tool for resolving genetic diversity also within other teleost species, which may be important for ecosystem management and conservation of genetic diversity. As reconstructions of ancient teleost fish faunas are often solely based on fossil otoliths, our discoveries may also lead to a new approach to research in palaeontology.
Highlights
Otoliths are aragonitic mineralizations that are arranged in three pairs in the inner ear of teleost fishes, where they play an important role in the senses of hearing and balance (Popper et al 2005)
The study is based on otolith morphology and two mitochondrial markers (D-loop, 16S rRNA) of three natural populations of Aphanius fasciatus (Teleostei: Cyprinodontidae) from Southeast Tunisia
We propose that otolith morphology is a valuable tool for resolving genetic diversity within other teleost species, which may be important for ecosystem management and conservation of genetic diversity
Summary
Otoliths are aragonitic mineralizations that are arranged in three pairs in the inner ear of teleost fishes, where they play an important role in the senses of hearing and balance (Popper et al 2005). Inter-population variability is known to occur widely in otoliths, especially with regard to size and contour, daily and annual growth rings, trace elements, and isotopic compositions. Fourier analysis and landmarks have been used to quantify otolith variation (size and contour) between species, populations, and even stocks Differences in otolith chemistry have been used for stock discrimination, analyses of population structure, reconstruction of the environmental history, and ecosystem monitoring Only a few studies have addressed the question whether inter-population differences in otolith traits are genetically encoded or the result of differences in certain habitat parameters (Torres et al 2000, Stransky et al 2008, Lombarte et al 2010, Vignon and Morat 2010)
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