Northern South America presents a diverse array of nonforest or savanna-like ecosystems that are patchily distributed. The distribution of these open habitats has been quite dynamic during Quaternary glacial-interglacial cycles; yet, the relevance of climatically driven vicariance events to the diversification of nonforest Amazonian vertebrates remains poorly known. We analyzed karyologic and mitochondrial DNA sequence data of the genus Zygodontomys, a small cricetid rodent distributed throughout nonforest habitats of northern Amazonia. Samples analyzed represented 4 Brazilian Amazonian localities and 2 French Guiana localities. Karyologic variation among Amazonian Brazilian Zygodontomys populations is high, with, at least, 3 karyomorphotypes. Molecular phylogenetic analyses recovered 3 major clades congruent with known karyotypes, a finding that suggests the existence of 3 species, 2 of which currently undescribed. The French Guiana and Surumú clade, identified as Zygodontomys brevicauda microtinus, is characterized by 2n = 86 and is sister to the clade formed by the 2 nondescribed forms. The Rio Negro-Rio Branco form is characterized by 2n = 82, and the Ferreira Gomes-Itapoá form is characterized by 2n = 84. The distribution of the 3 Zygodontomys lineages identified is in accordance with the geography of the open vegetation patches in Northern Amazonia, and divergence time estimates relate speciation events to the middle-upper Pleistocene, supporting the prominent role of Quaternary climatically driven vicariance events in the diversification of the genus.

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vicariance events nonforest amazonian vertebrates genus karyologic and mitochondrial dna sequence data open vegetation branco middleupper climatically

Cibele R, Bonvicino Pablo R, Gon?alves Jo?o A, de Oliveira Luiz Flamarion B, de Oliveira Margarete S, Mattevi,.Divergence in Zygodontomys (rodentia: Sigmodontinae) and distribution of amazonian savannas.. 100 (3),322-8.

Cibele R, Bonvicino Pablo R, Gon?alves Jo?o A, de Oliveira Luiz Flamarion B, de Oliveira Margarete S, Mattevi,"Divergence in Zygodontomys (rodentia: Sigmodontinae) and distribution of amazonian savannas." 100

Cibele R, Bonvicino Pablo R, Gon?alves Jo?o A, de Oliveira Luiz Flamarion B, de Oliveira Margarete S, Mattevi,"Divergence in Zygodontomys (rodentia: Sigmodontinae) and distribution of amazonian savannas."