Inter-population differences in otolith morphology are genetically encoded in the killifish <i>Aphanius fasciatus</i> (Cyprinodontiformes)

Abstract

SUMMARY: 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.Keywords: Cyprinodontidae, phylogeography, gene flow, local adaptation, otolith morphometry, mitochondrial markers. RESUMEN: Las diferencias inter-pobLacionaLes en La morfoLogía deL otoLito de AphAnius fAsciAtus (cyprinodontiformes) se codifican genéticamente. -Las diferencias en la forma del otolito entre poblaciones, la morfología o la química se han utilizado con efectividad como indicadores para la gestión de poblaciones o para el reconocimiento de adaptaciones ambientales en peces. Sin embargo, los parámetros precisos que afectan la morfología del otolito permanecen sin ser entendidos completamente. Aquí nosotros presentamos la primera evidencia directa para la hipótesis de que las diferencias inter-poblacionales en la morfología del otolito están codificadas genéticamente. El estudio se basa en la morfología del otolito y dos marcadores mitocondriales (D-loop, 16S rRNA) de tres poblaciones naturales de Aphanius fasciatus (Teleostei: Cyprinodontidae) del sudeste de Tunez. Los datos de otolitos y genéticos ofrecen tres topologías congruentes. Aparentemente la divergencia entre poblaciones resulta de los procesos de aislamiento durante los descensos del nivel del mar en el Pleistoceno. Proponemos que la morfología del otolito es una herramienta muy valiosa para entender la diversidad genética también con otras especies de peces, que puede ser importante para la gestión de los ecosistemas y la conservación de la diversidad genética. Ya que las reconstrucciones de la fauna antigua de peces teleósteos se basan a menudo en otolitos fósiles, nuestro hallazgo puede también ser importante como nueva aproximación en las investigaciones palentológicas.

Otoliths as individual indicators: a reappraisal of the link between fish physiology and otolith characteristics

“…Consequently, the importance of the genotype with regard to shaping both the physiological and the otolith response to natural environmental variability should not be underestimated ). Recently, the implicit assumption of many otolith shape studies, namely a population-specific genetic component to otolith shape, has been substantiated (Vignon and Morat 2010;Annabi et al 2013), adding further to the link between genetic make-up and otolith characteristics of populations and individuals.…”

Investigation of otolith mass asymmetry in three stocks of European sardine, Sardina pilchardus (Walbaum, 1792) from Türkiye

“…Differences in OMA may be affected by the ecological conditions, physiological state of species and its habitat (Grønkjaer, 2016). Both genetic and environmental conditions have an impact on the morphological variability of sagitta (Lombarte et al, 2010;Annabi et al, 2013). Additionally, changes in otolith mass asymmetry can have a deleterious impact on other aspects of fish life, particularly their ability to hear and balance.…”

Enigmatic fish ear stones: Ontogenetic development of saccular otolith in an endemic toothcarp of the Arabian peninsula, Aphaniops kruppi (Teleostei: Aphaniidae)

“…A review of otolith‐related literature reveals that ear stones of members of the Aphaniidae family have attracted a lot of attention in phylogenetical, biogeographical, and paleontological studies (Chiozzi et al, 2018; Esmaeili et al, 2018; Ferrito et al, 2013; Reichenbacher & Kowalke, 2009; Wildekamp, 1993). Otolith‐based studies on this family have been done about species and population identifications, past vicariance events, population connectivity, and ontogenetic development (Annabi et al, 2013; Gholami, Esmaeili, Erpenbeck, & Reichenbacher, 2015; Gholami, Esmaeili, & Reichenbacher, 2015; Reichenbacher et al, 2007; Reichenbacher, Feulner, & Schulz‐Mirbach, 2009; Teimori, Jawad, et al, 2012; Teimori, Schulz‐Mirbach, et al, 2012). New researches conducted on the ontogeny of some aphaniids of the middle east such as Aphanius darabensis , A .…”