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1 August 2013 Differentiation in the Atlantic Forest: phylogeography of Akodon montensis (Rodentia, Sigmodontinae) and the Carnaval–Moritz model of Pleistocene refugia
Lourdes Valdez, Guillermo D’Elía
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Abstract

According to the Carnaval–Moritz (CM) model of Pleistocene refugia, during the Last Glacial Maximum, forested areas of the Atlantic Forest (AF) were restricted to isolated refugia and later expanded to their current distribution. Phylogeographic patterns of several vertebrate species corroborated the existence of the so-called Pernambuco, Bahia, and São Paulo refugia in the central and northern AF. Here we shift focus to the neglected southern and interior AF by addressing the phylogeography of the mouse Akodon montensis as inferred through analysis of cytochrome-b gene sequences of 86 specimens collected at 36 localities in Argentina, Brazil, and Paraguay. Three main clades were recovered with average genetic divergence of 2.5%: a northern clade, differentiated in the Bahia refuge, a southern clade—for which we propose the Rio Grande do Sul refugium—and a central clade (widely extending from coastal Brazil to Argentina and Paraguay). Within the latter, genetic diversity and historical demographic estimations support differentiation in the São Paulo refugium and their later population expansion toward interior AF. Additionally, no riverine barrier effect was found associated with the main river in the interior AF, the Paraná River. Taken as a whole, the phylogeographic pattern of A. montensis and its recent population history are mainly concordant with the CM model.

Según el modelo Carnaval–Moritz de refugios Pleistocénicos, durante el Último Máximo Glacial, el Bosque Atlántico (BA) se fragmentó a refugios aislados desde los cuales posteriormente se expandieron hasta ocupar su distribución actual. Los patrones filogeográficos de varios vertebrados corroboran la existencia de los refugios de Pernambuco, Bahía y São Paulo en las zonas central y norte del BA. En este estudio nos enfocamos en el BA sur e interior mediante el estudio filogeográfico del ratón Akodon montensis en base a secuencias del gen citocromo–b de 86 especímenes colectados en 36 localidades en Argentina, Brasil y Paraguay. Se observaron 3 clados principales que divergen en promedio en 2.5%; un clado norte, diferenciado en el refugio de Bahía; un clado sur que se diferencia en el aquí propuesto refugio de Río Grande do Sul; y un clado central ampliamente distribuido desde la costa de los estados de Río de Janeiro y São Pablo en Brasil hasta el Paraguay oriental. Dentro de éste último, las estimaciones de diversidad genética y demografía histórica sustentan un escenario de diferenciación en el refugio de São Pablo y posterior expansión poblacional hacia el BA interior. Adicionalmente, se muestra que el Río Paraná no afecta la estructura filogeográfica de A. montensis en el BA interior. En su conjunto, el patrón filogeográfico de A. montensis y su historia poblacional reciente son concordantes con el modelo Carnaval–Moritz.

Lourdes Valdez and Guillermo D’Elía "Differentiation in the Atlantic Forest: phylogeography of Akodon montensis (Rodentia, Sigmodontinae) and the Carnaval–Moritz model of Pleistocene refugia," Journal of Mammalogy 94(4), 911-922, (1 August 2013). https://doi.org/10.1644/12-MAMM-A-227.1
Received: 6 September 2012; Accepted: 1 March 2013; Published: 1 August 2013
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