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Phenotypic and genetic differentiation between diadromous and landlocked puyen Galaxias maculatus.

We studied phenotypic and genetic differences between individuals of puyen Galaxias maculatus from two sites in the same river basin in Tierra del Fuego National Park, southern South America. Individuals from the two sampling sites presented morphometric and genetic differences. The morphometric differences indicated that individuals from Laguna Negra (LN) were shorter, more robust, and with larger eyes, whereas those from Arroyo Negro (AN) were thinner, elongated, and with smaller eyes. Genetic differences showed that AN individuals had a greater genetic structuration and an older demographic history than LN individuals. From our results, we could affirm that the individuals from the two sampling sites belong to different populations with a high degree of isolation. The demographic history could indicate that the individuals of G. maculatus which migrated to northern areas during the last glaciation settled in the Beagle Channel after its formation. The LN population could have originated after the retreat of the glaciers, migrating from AN. This article is protected by copyright. All rights reserved.