Navegando por Palavras-chave "Parthenogensis"

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    Origem e diversificação do lagarto partenogenético Loxopholis percarinatum (gymnophthalmidae: ecpleopodini), um complexo de espécies endêmico da Amazônia
    (Universidade Federal de São Paulo, 2016-11-22) Silva, Andre Robson Justino da [UNIFESP]; Pellegrino, Katia Cristina Machado [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The small lizards of the genus Loxopholis inhabit the leaf litter of Central and South America tropical forests. The genus includes 10 bisexual species and the unisexual L. percarinatum, the latter widely distributed throughout the Amazon forest. Previous studies based on a small sample (N=20) suggested that L. percarinatum is a species complex with diploid (2n=44) and triploid (3n=66) lineages. Recently, the first males were described from two populations of L. percarinatum at the northwestern Amazon, suggesting the existence of bisexual populations in the complex. Until now, the origin of parthenogenesis of L. percarinatum it is not clear. This study aims to expand the previous works in number of individuals, geographical localities sampled and nuclear markers analysed, in order to: i) reconstruct the phylogenetic relationships among the unisexual 2n and 3n lineages with the bisexual populations, as well as between the complex and the remaining species of Loxopholis, advancing in the comprehension about the origin of parthenogenesis in the L. percarinatum species complex; ii) characterize the genetic divergence of the species complex; e iii) investigate the genetic and geographic structure of the 2n and 3n lineages. Sample consisted of 98 specimens of L. percarinatum from 56 localities of Brazil and two from French Guiana, and also eight species of Loxopholis (guianense, ferreirai, hexalepis, osvaldoi, parietale, snethlageae, rugiceps e southi). Partial sequences from mtDNA (NADH4 + tRNA histidine: 682bp) and nuclear DNA (NT3 and KIAA2018: 1085bp) were obtained. Phylogenetic analyses included Bayesian Inference and Maximum Likelihood, and haplotype genealogies and genetic divergence (pairwise distance) were estimated. The mtDNA recovered three main well-supported lineages: unisexual 2n (Uni/2n), unisexual 3n (Uni/3n) e bisexual with two sub-lineages (Santa Isabel do Rio Negro e Rio Jufari, AM). The bisexual populations ascribed to L. percarinatum were grouped sister to the Uni/3n lineage, with high support. Large mtDNA genetic divergences between the unisexual and bisexual (8.8%) and between the 2n and 3n (10.3%) lineages corroborate the ancient process of diversification for this species complex. Both mtDNA and nDNA greatly suggest that specimens from Santa Isabel do Rio Negro represent a potential new species, contrary to a previous study based on morphology. This still undescribed species and assigned to the bisexual 2n (Bis/2n) lineage, seems to be related to the origin of the parthenogenesis, being the maternal parent of both Uni/2n e Uni/3n lineages. The combined analyses of nDNA regions indicated L. ferreirai and L. hexalepis as the closest species to the L. percarinatum complex; the former as a potential paternal parent. Finally, hypotheses implying hybridization events of those mentioned species are herein proposed, however a spontaneous origin of the parthenogenetic L. percarinatum species complex cannot be rejected.