Genetic and phenotypic differentiation among Galaxias maculatus populations in a Patagonian postglacial lake system

Abstract

Understanding the influence of landscape features on population differentiation is fundamental to evolutionary biology studies. We examined spatial patterns of genetic and phenotypic variability among Galaxias maculatus populations in a complex of four postglacial lakes in northwestern Patagonia differing in size and connectivity among them. A hierarchical Bayesian analysis grouped the individuals collected from eleven localities into three genetic clusters, first defining the populations of the two large lakes and separating the two small lakes in subsequent analysis. Genetic structuring was restricted within large lakes. It is known that the larval stage of Galaxias maculatus migrate to the limnetic zone of Patagonian lakes, possibly exerting an homogenizing effect on gene flow within lakes. Gene flow asymmetry and divergences among lakes can be explained by a combination of landscape characteristics and the presence of predators in the short streams that connect them. Individuals from the small lakes are the most divergent morphologically and genetically. The population in the isolated Redonda Lake, exhibits meristic differences as well, suggesting strong drift and environmental effects. This population is likely to have been isolated following the decline in water level of a paleolake that existed in this region approximately 13.2 kya BP. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Phenotypic and genetic differentiation between diadromous and landlocked puyen Galaxias maculatus

“…In addition, the diadromous life history of G. maculatus implies the upstream movement of whitebait that return from the sea after their period of larval growth; this migration could require a better swimming performance. In northern Patagonia, it has already been found that G. maculatus larvae in environments with a lower risk of predation have a shorter caudal peduncle than those in environments with higher predation pressure (Barriga et al, 2012). A thinner caudal peduncle in diadromous populations of this species was also found (Ferriz & Gómez, 2015), a functional morphology associated with a greater swimming velocity or higher resistance (Webb, 1984).…”

“…The sea level reached its maximum (~10 m above current sea level) about 6400 yr BP descending then to its current position (Gordillo & Cárdenas, 2008;Rabassa et al, 2009). This marine regression-transgression modified and modelled the environment, especially the water basins and inland water bodies (Clapperton, 1993), thus impacting the current configuration of fish populations because changes in the population size of species at high latitudes are generally interpreted in terms of Quaternary climate cycles (Carrea et al, 2012;Ceballos et al, 2012;González-Wevar et al, 2015).…”

Geographical isolation and genetic differentiation: the case ofOrestias ascotanensis(Teleostei: Cyprinodontidae), an Andean killifish inhabiting a highland salt pan

“…Variations in lacustrine levels and geomorphological processes may cause fragmentation of the *Corresponding author. E-mail: mmendez@uchile.cl environment and the aquatic biota that inhabit these systems, favouring evolutionary processes (Kornfield & Smith, 2000;Waters et al, 2001;Elmer et al, 2010;Carrea et al, 2012;Vogiatzi et al, 2014). The tectonic activities and water level fluctuations in the African Great Lakes are a classic example of this phenomenon, which may have promoted the diversification in the cichlid species flock (Sturmbauer et al, 2001;Verheyen et al, 2003;Joyce et al, 2005;Nevado et al, 2013).…”

Genetic and phenotypic variation among Galaxias maculatus populations reflects contrasting landscape effects between northern and southern Patagonia

“…Non-migratory G. maculatus populations from Australia and New Zealand show a reduced number of vertebrae, with 49 vertebrae at the extreme compared with around 62 in diadromous stocks (Ling et al, 2001). Similarly, in South America, the lowest vertebral count recorded for landlocked populations is 50 (Carrea et al, 2012). Furthermore, vertebral count is correlated with latitude for diadromous G. maculatus populations across its distribution range (McDowall, 2003a).…”

“…Freshwater fishes offer a good opportunity to study the influence of landscape on genetic diversity since they are intrinsically tied to the hydrological structure they inhabit (Gomez-Uchida, Knight & Ruzzante, 2009;Carrea et al, 2012). The hydrological landscape in Patagonia was affected differentially across its latitudinal range by Quaternary glaciations.…”