Morphometric and meristic variation in Galician threespine stickleback populations, northwest Spain

Abstract

SynopsisWe evaluated morphological differentiation among populations of threespine stickleback, Gasterosteus aculeatus, from the Limia and Min˜o basins (Galicia, NW Spain), the river Karup (Denmark) and Aiguamolls de l'Emporda`(Girona, northeast Spain), using multivariate analysis of morphometric and meristic characters. Multivariate discriminant analysis and hierarchical cluster analysis uncovered significant differences among the four main groups, between the two groups from Galicia and among populations within the Min˜o basin. The stickleback from Galicia differed from the Danish group in head and body armour characters. Between the Min˜o and Limia groups, we found differences in both head and body proportions as well as in number of gill rakers. Within the Min˜o basin populations varied with respect to head and body armour traits and the number of lower gill rakers. Clustering analysis divided these populations into two groups based on the latter trait: fish from the upper section of river Min˜o and tributaries (a lower number of lower gill rakers) and fish from the central and lower reaches of the river. Overall, morphometric traits were more useful than meristic ones; however, the two types of data provided congruent information about the morphological differentiation of stickleback populations.

Geographical and Temporal FA Variation in Threespine Stickleback Populations from Galicia (NW Spain)

“…However, associations between symmetric fishes and the presence of S. solidus have been previously reported in G. aculeatus (Reimchen, 1997;Reimchen and Nosil, 2001c), being the cause of this pattern related to the different ecological niches that symmetric and asymmetric individuals exploit, which results in an unequal exposure to parasites (Reimchen and Nosil, 2001a, b). The number of gillrakers is a highly variable and heritable trait in Galician sticklebacks (Hermida et al, 2002), and variation in diet seems to be an important factor in the morphological variation among Galician populations (Hermida et al, 2005). Our data supports the idea that ecological differences between hosts could be an important component of patterns of parasitic infection in natural populations of G. aculeatus, and that this pattern is not exclusive to the populations previously studied (e.g.…”

“…The effects of environmental stress on developmental stability have been established in a wide range of organism (Møller and Swaddle, 1997;Palmer and Strobeck, 2003). On other hand, most of the populations considered here are presumed to be isolated populations (Hermida et al, 2005). Isolated populations may vary in their ''genetic quality'', with elevated levels of homozygosity being a possible general cause of increased FA (Møller and Swaddle, 1997).…”

“…Sampling protocols, measuring and counting procedures are detailed in Hermida et al, 2005. To ensure that the meristic characters were completely developed, only adults larger than 25 mm were used (Baumgartner, 1992;Moodie and Moodie, 1996). To assess the variation in FA, five meristic and one morphometric bilateral characters were selected.…”

Morphometric and meristic variation in two congeneric archer fishes Toxotes chatareus (Hamilton 1822) and Toxotes jaculatrix (Pallas 1767) inhabiting Malaysian coastal waters

“…Extreme outliers are defined as those which lie more than three times the inter-quartile range to the left or right of the first and third quartiles, respectively. Separate statistical analyses were conducted on morphometric and meristic data since morphometric data are continuous and more susceptible to the environmentally induced variability, while meristic data are discrete and fixed early in development (Ihssen et al, 1981;Hermida et al, 2005;Turan et al, 2006). Spearman's rank correlation indicated that there was a low association between meristic characters and standard length (SL) of the samples.…”

Análise morfométrica em Thoracocharax stellatus (Kner, 1858) (Characiformes, Gasteropelecidae) proveniente de diferentes bacias hidrográficas Sul-americanas

“…Já a altura do corpo e comprimento do maxilar foram os mais importantes na discriminação da população do Orinoco na variável canônica 2. Embora a análise de caracteres morfométricos seja útil na identificação de amostras de diferentes rios, mesmo que estes estejam geograficamente próximos (Hermida et al 2005), a considerável sobreposição dos valores dos caracteres individuais das populações que compõem a Bacia do rio Paraguai (SE, SG e BB), não permitiu a distinção destas sub-populações. Este fato permite sugerir que, até o momento, a distância entre as sub-populações desta bacia, não se configura como um mecanismo de isolamento a ponto de distinguir morfologicamente as populações por meio desta metodologia.…”