Use of geometric morphometrics to identify ecophenotypic variation of juvenile Persian sturgeon <em>Acipenser persicus</em>

Abstract

Summary: Study of phenotypic variation is essential for identifying discrete phenotypic stocks. We sampled immature Persian sturgeon from the eastern and western portion of the southern Caspian Sea to test for morphological differences that could predict the ecophenotypic variation of Persian sturgeon. Geometric morphometric methods were used to quantify body shape. Configuration of landmark coordinates of fish body were scaled, translated and rotated using generalized Procrustes analysis, followed by univariate analysis of variance of resulting shape coordinates to evaluate potential morphological differences between regions. A principal component analysis was carried out to reduce the number of dimensions without the loss of information. The discriminate function analysis was performed to determine the efficacy of body landmarks for discrimination by geographic variants. Within-group linkage was inferred for dendrogram clusters using Pearson correlation distance on the basis of the average linkage method as a complement for discriminate analysis. Principle component analysis revealed that the largest differences were in body size. Most notable were differences in distance between head landmarks and the dorsal fin between eastern and western regions. Fish from the western region exhibited a longer distance from head landmarks to the dorsal fin than fish from the eastern region. Furthermore, the ventral portion of fish from the western region was longer than that of the eastern individuals. These findings show that juvenile Persian sturgeon already possess morphological traits that can be used to discriminate fish from different regions. Furthermore, these differences are discernible in spite of the volume of artificially-inseminated sturgeon larva that have been released during the past 40 years.Keywords: geometric morphometric selection, phenotypic plasticity, discrimination, habitat. Uso de morfometría geométrica para la identificación de variaciones ecofenotípicas en juveniles de esturión persa Acipenser persicusResumen: El estudio de la variación fenotípica es esencial para la identificación de estirpes fenotípicas concretas. Con el fin de identificar diferencias morfológicas que permitan predecir variaciones eco-fenotípicas en el esturión persa, individuos inmaduros de esta especie se muestrearon en diferentes regiones del este y el oeste del sur del mar Caspio. Se utilizaron métodos morfométricos geométricos para cuantificar la forma del cuerpo. La configuración de coordenadas referenciadas del cuerpo del pez fueron escaladas, trasladadas y rotadas utilizando el análisis generalizado Procrustes, seguido del análisis Univariante de la Varianza de las coordenadas de forma resultantes, con el fin de evaluar posibles diferencias morfológicas entre diferentes zonas. Se utilizó un análisis de componentes principales para reducir el número de dimensiones sin perder información. Los scores de los componentes del cuerpo se sometieron a análisis discriminante, con el objeto de determinar la eficacia de las coordena...

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