The use of PCR-RFLP as an identification tool for three closely related species of rodents of the genus Akodon (Sigmodontinae, Akodontini)

Abstract

Three cryptic species of the rodent Akodon (A. cursor, A. montensis and Akodon sp.) were analyzed. The two former species are sympatric in the Brazilian states of São Paulo, Rio de Janeiro and Minas Gerais, where hybrids have already been found. The third species, Akodon sp., occurs in an isolated area in Central Brazil. The identification of these species is difficult by the need of living animals. At present, karyotyping is the only method used in the identification of specimens. We used PCR-RFLP of the mitochondrial cytochrome gene to test the distinctiveness of the three species, which was confirmed by the absence of shared species-specific haplotypes. We also detected a geographical pattern of haplotypes distribution with highly polymorphic populations of A. cursor from Espírito Santo and of A. montensis from Rio Grande do Sul.

Akodon cursor(Rodentia: Cricetidae)

“…aff. cursor was considered a different species (Geise et al 2005;Smith and Patton 2007), but it is now described as a karyotypic variant of A. cursor (Fagundes and Nogueira 2007;Geise et al 2001;Pereira 2006). When compared to A.…”

“…However, some confusion occurred in the past, until the name A. cursor was applied to specimens with a diploid number of 14, 15, or 16 chromosomes. A specimen with 14 chromosomes was collected near the type locality of A. cursor (Rieger et al 1995), leading subsequent authors to associate such a karyotype to this species (e.g., Fagundes and Nogueira 2007;Geise et al 1998Geise et al , 2001Sbalqueiro and Nascimento 1996), contrary to A. montensis, with a diploid number of 24 or 25. In an analysis of 20 craniometric characters, the most useful in distinguishing A. cursor and A. montensis from each other was the length of the upper molar series, always >4.4 mm in A. cursor and <4.4 mm in A. montensis (Geise et al 2005;Goncalves et al 2007).…”

Identificação das espécies brasileiras de Akodon (Rodentia: Cricetidae: Sigmodontinae) através da microestrutura dos pelos

“…Para A. mystax (Hershkovitz 1998), A. toba (Thomas 1921), A. reigi (González et al 1998), A. lindberghi (Hershkovitz 1990 (Musser & Carleton 2005), cujos estudos na sua grande maioria, são de caráter sistemático e desenvolvidos na Argentina (Del Valle & Busch 2003, Pereira et al 2005, Pardiñas & Teta 2007, Braun et al, 2008, 2010, Pardiñas 2009, no Brasil (Fagundes et al 1998, Geise et al 1998, Sbalqueiro & Nascimento 1996, Fagundes & Nogueira 2007, Queirolo & Granzinolli 2009), na Bolívia (Myers & Patton 1989a, Braun et al, 2008, no Chile (Simonetti et al 1985, Meserve et al 1991, Antinuchi & Busch 2000, no Paraguai (Yahnke 2006, Braun et al, 2008 e, no Peru e Bolívia (Myers & Patton 1989b, Myers et al 1990.…”

“…Entretanto, essas técnicas requerem investimentos maiores e se tornam inviáveis na identificação individual em estudos de ecologia de populações (Fagundes & Nogueira 2007).…”

“…Assim, considerando a grande dificuldade em diferenciar morfologicamente as espécies de Akodon, somada à possibilidade de ocorrência de algumas espécies em simpatria e de variações cromossômicas existentes dentro da mesma espécie (Fagundes & Nogueira 2007), nosso intuito é identificar nove espécies brasileiras do gênero Akodon com base na microestrutura do pelo e avaliar se há alguma característica morfológica do pelo que possa estar relacionada com a conhecida variação cromossômica existente para a espécie Akodon cursor. como multisseriada alveolar, multisseriada listrada e um misto entre alveolar e listrada (Figura 2).…”