Genetic and morphologic differentiation of the Lusitanian toadfish (<i>Halobatrachus didactylus</i>) between estuarine and coastal areas in Portugal

Abstract

SUMMARY: The Lusitanian toadfish, Halobatrachus didactylus (Bloch and Schneider, 1801), is distributed from the Ghana coast to the Iberian Peninsula, being particularly abundant on the south coast of Portugal. The differentiation of this species along the Portuguese coast was assessed through the analysis of 10 samples, considering morphological characters (20 morphometric and 16 meristic) and genetic markers (10 allozymes, 11 loci). Southern samples included estuaries and their adjacent coastal areas, given that this species inhabits both environments, whereas western samples only comprised estuaries. Morphometric and meristic data discriminant analysis evidenced some differentiation between estuarine and coastal populations. This was not entirely corroborated by the genetic analysis, which showed an overall pattern of low F ST (0.042) and Nei's genetic distance, even between geographically distant areas. However, higher values of these parameters were found between estuaries of the south coast and their adjacent coastal areas, suggesting that estuarine systems play a major role in such differentiation. Results are discussed regarding toadfish life-history pattern and Portuguese coast geomorphology, giving an insight into the biological and environmental factors influencing population sub-structuring.Keywords: Halobatrachus didactylus differentiation, allozymes, morphology, population structure, coastal areas RESUMEN: DIFERENCIACIÓN MORFOLÓGICA Y GENÉTICA DEL PEJESAPO (HALOBATRACHUS DIDACTYLUS) ENTRE ESTUARIOS Y ÁREAS COSTERAS DE PORTUGAL. -El pejesapo, Halobatrachus didactylus (Bloch y Schneider, 1801), está distribuido desde la costa de Ghana hasta la Península Ibérica, siendo particularmente abundante en la costa sur portuguesa. La diferenciación de esta especie a lo largo de la costa Portuguesa se ha evaluado a través del análisis de diez muestras, considerando caracteres morfológicos (20 características morfométricas y 16 merísticas) y genéticos (10 aloenzimas, 11 loci). Hacia el sur, las muestras incluyen estuarios y sus áreas costeras adyacentes, ya que esta especie habita ambos ambientes, mientras que las muestras del oeste están relacionadas sólo a estuarios. El análisis discriminante de los datos morfométricos y merísticos evidenciaron diferenciación entre poblaciones de estuarios y costeras, lo cual no fue enteramente corroborado por el análisis genético, el cual mostró un patrón general de bajo F ST (0.042) y distancia genética de Nei, incluyendo áreas geográficamente distantes. Sin embargo, valores más altos de estos parámetros fueron encontrados entre estuarios de la costa sur y sus áreas costeras adyacentes, sugiriendo que los sistemas de estuarios juegan un papel importante en tal diferenciación. Los resultados son discutidos considerando los patrones de historia de vida del pejesapo y la geomorfología de la costa portuguesa, dando una perspectiva de cómo los procesos biológicos y factores ambientales influyen la sub-estructuración poblacional.Palabras clave: Halobatrachus didactylus diferenciac...

Development and characterization of novel microsatellite loci for Lusitanian toadfish,Halobatrachus didactylus

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