Abstract

MORA, Matías S; KITTLEIN, Marcelo J; VASSALLO, Aldo I  and  MAPELLI, Fernando J. Diferenciación geográfica en caracteres de la morfología craneana en el roedor subterráneo Ctenomys australis (Rodentia: Ctenomyidae). Mastozool. neotrop. [online]. 2013, vol.20, n.1, pp.75-96. ISSN 0327-9383.

We assess geographical morphological differentiation in the subterranean rodent Ctenomys australis, which is distributed in the first line of coastal sand dunes between the localities of Necochea and Punta Alta, province of Buenos Aires, Argentina. Using a multivariate Discriminant Function Analysis (DFA), we evaluate geographic variation as congruent with an isolation by distance model and its correspondence with the patern of differentiation reported for molecular markers like mitochondrial DNA (apparently neutral) and allozymes. Drif in conjunction with both low rates of migration and the isolation among localities are expected to be the main factor to explain an important fraction of the morphological variation at the geographic level. This general prediction of isolation by distance does not rule out the presence of adaptive or environmentally induced morphological variation. First, we observed isolation by distance in both the morphological Mahalanobis distances and the allozyme distances, which were correlated with the geographic distances between localities. A large portion of the phenotypic variation, like variation in skull morphology or the alloenzymatic variation, could be also related with diferent components of local adaptation and/or environmental induced variation, in a parallel context to the recent signal of demographic expansion previously detected in the mitochondrial DNA. This situation suggests that a portion of morphological variation might be subjected to selection and has a relation with local adaptive processes, resulting in rapid rates of evolution in comparison to the mtDNA genome, which has a strong footprint of demographic history.

Keywords : Allozymes; Buenos Aires; Isolation by distance; Morphological differentiation; mtDNA.

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