Filogeografia e citogenética do gênero Kerodon (CUIVER, 1825) (RODENTIA: CAVIIDAE)
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2014-04-24
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Universidade Federal de Viçosa
Resumo
Entre os mamíferos dos biomas brasileiros, os roedores do gênero Kerodon (Wied 1820), ou mocó, são um dos táxons mais especializados. Uma de suas espécies, o Kerodon rupestris, um dos poucos mamíferos endêmicos do semiárido brasileiro, a caatinga, possui sua distribuição fragmentada devido à descontinuidade dos afloramentos rochosos onde eles vivem, e isso favorece uma variação intraespecífica entre suas populações. A outra espécie do gênero, K. acrobata, vive em uma pequena área do cerrado, entre os estados de Tocantins e Goiás. O objetivo deste trabalho foi a caracterização citogenética de uma fêmea de Kerodon acrobata e molecular das duas espécies de Kerodon. Foi caracterizado o cariótipo de uma fêmea de K. acrobata, utilizando coloração Giemsa, bandeamento NOR, bandeamento de heterocromatina e fluorescência com DAPI. O espécime mostrou o mesmo número diploide, número fundamental e morfologia cromossômica que Kerodon rupestris. Porém, as localizações de NOR e de heterocromatina indicaram padrões diferentes em relação a outros roedores, enfatizando a singularidade dessa espécie. O DNA foi extraído de tecido hepático das duas espécies e amplificações foram feitas para o gene nuclear Adh1-I2. Após sequenciamento, alinhamentos foram realizados com o ClustalW. A filogenia foi inferida usando os métodos Máxima Parcimônia e Máxima Verossimilhança usando o PAUP e Análise Bayesiana, com o MrBayes. Uma rede de haplótipo foi realizada com os programas DnaSP e Network. O gene nuclear mostrou dois grupos bem estruturados: o primeiro formado por K acrobata sem resolução interna, e o segundo que incluiu as populações de K rupestris e três sequências do chamado híbrido . Os dados obtidos sugerem alta diferenciação citogenética e molecular entre K rupestris e K acrobata, indicando diferentes idades entre elas. O chamado híbrido pode representar uma população altamente divergente dentro de K rupestris, como resultado dentro da dinâmica de expansão e retração pleistocênica da caatinga.
Among mammals from Brazilian biomes, rodent of genus Kerodon (Wied 1820), or mocó, englobes one of the most specialist species and one of the few endemic mammals from Brazilian semiarid, or caatinga, Kerodon rupestris, and other species from semi-arid islands within the savannah, or cerrado, Kerodon acrobata. Their distribution is fragmented, due to discontinuous rock outcrops where these animals live. It suggests an intraspecific variation among their populations. Cranial and cytogenetic studies with K. rupestris had showed a separation in three groups: one in Minas Gerais state, other in Bahia and the last in Ceará. This study investigated genes from populations of Kerodon species, in order to make analysis to check inter and intra variation. A small group from another locality, probably a hybrid, was also analyzed. We first characterize the karyotype of a female from K. acrobata. Giemsa staining, nucleolar organizer region (NOR) banding, C-positive heterochromatin banding and DAPI fluorescence were used in N metaphases of a specimen collected in Asa Branca Farm, in Aurora do Tocantins municipality, Tocantins state, Brazil. K. acrobata showed the same diploid number, fundamental number and chromosome morphology as Kerodon rupestris. But its NOR location and heterochromatin distribution patterns indicated a unique cytogenetic profile when compared to its sister species, emphasizing the evolutionary uniqueness of this relatively new and unknown species. This record also extends the distribution of this species northward. We also extracted DNA from livers and amplifications were made for gene Adh1-I2. After sequencing, alignments were done with ClustalW software. Phylogeny was inferred using Maximum Parsimony and Maximum Likelihood methods using PAUP software. Bayesian Analysis was also made, using MrBayes software. One haplotype network was done with DnaSP and Network. All trees and network showed similar results. These relations agree with variation observed in previous studies, separating K. rupestris populations in several groups. K. acrobata was also split in other groups, and some results indicate that the hybrid population is in fact a K. rupestris group in speciation. A possible explanation for these partitions is the fact that rock outcrops fragmented geography from caatinga during Pleistocene and events of expansion/retraction of the habitat may have generated population isolation and differentiation.
Among mammals from Brazilian biomes, rodent of genus Kerodon (Wied 1820), or mocó, englobes one of the most specialist species and one of the few endemic mammals from Brazilian semiarid, or caatinga, Kerodon rupestris, and other species from semi-arid islands within the savannah, or cerrado, Kerodon acrobata. Their distribution is fragmented, due to discontinuous rock outcrops where these animals live. It suggests an intraspecific variation among their populations. Cranial and cytogenetic studies with K. rupestris had showed a separation in three groups: one in Minas Gerais state, other in Bahia and the last in Ceará. This study investigated genes from populations of Kerodon species, in order to make analysis to check inter and intra variation. A small group from another locality, probably a hybrid, was also analyzed. We first characterize the karyotype of a female from K. acrobata. Giemsa staining, nucleolar organizer region (NOR) banding, C-positive heterochromatin banding and DAPI fluorescence were used in N metaphases of a specimen collected in Asa Branca Farm, in Aurora do Tocantins municipality, Tocantins state, Brazil. K. acrobata showed the same diploid number, fundamental number and chromosome morphology as Kerodon rupestris. But its NOR location and heterochromatin distribution patterns indicated a unique cytogenetic profile when compared to its sister species, emphasizing the evolutionary uniqueness of this relatively new and unknown species. This record also extends the distribution of this species northward. We also extracted DNA from livers and amplifications were made for gene Adh1-I2. After sequencing, alignments were done with ClustalW software. Phylogeny was inferred using Maximum Parsimony and Maximum Likelihood methods using PAUP software. Bayesian Analysis was also made, using MrBayes software. One haplotype network was done with DnaSP and Network. All trees and network showed similar results. These relations agree with variation observed in previous studies, separating K. rupestris populations in several groups. K. acrobata was also split in other groups, and some results indicate that the hybrid population is in fact a K. rupestris group in speciation. A possible explanation for these partitions is the fact that rock outcrops fragmented geography from caatinga during Pleistocene and events of expansion/retraction of the habitat may have generated population isolation and differentiation.
Descrição
Palavras-chave
Mocó, Citogenética, Filogeografia, Mocó, Cytogenetics, Phylogeography
Citação
ZAPPES, Ighor Antunes. Phylogeography and cytogenetics of the genus Kerodon (CUIVER, 1825) (RODENTIA: Caviidae). 2014. 55 f. Dissertação (Mestrado em Biologia e Manejo animal) - Universidade Federal de Viçosa, Viçosa, 2014.