Comparison between Oligoryzomys nigripes and O. flavescens by RAPD and genetic diversity in O. nigripes (Rodentia, Cricetidae)

Abstract

The genus of Oligoryzomys includes species of small size, morphologically similar, which may impede taxonomic identification, mainly between O. flavescens (Waterhouse, 1837) and O. nigripes (Olfers, 1818). The main objective of this work was to investigate whether the RAPD markers are capable of genetically differentiating the specimens O. nigripes and O. flavescens, coming from Rio Grande do Sul (RS) and Santa Catarina (SC) states, and also to estimate the genetic variability among populations of O. nigripes, with the Uruguay River as a geographical barrier. For this purpose, samples were collected in fragments of forests situated in the North of RS, at FLONA (Floresta Nacional de Passo Fundo) and in fragments from SC, close to the Uruguay River. The karyotyping of two samples for each species was carried out and compared using the RAPD technique together with non-karyotyped individuals. Samples of O. nigripes presented 2n = 62; NA = 82, with submetacentric arms on the largest chromosomes, while samples of O. flavescens showed 2n = 64; NA = 66, with the largest chromosomes presenting acrocentric morphology, making such a result the main difference between the species. The analysis was able to detect two distinct groups, being the first one with karyotyped O. flavescens and the second with karyotyped O. nigripes. Identification afforded 211 loci, among them 181 (85.78%) polymorphic. The Jaccard similarity coefficient was in the range of 0.45 to 0.87. The UPGMA and Main Coordinate Analysis techniques demonstrated the existence of heterogeneous genetics among populations, but did not separate them completely in terms of geographical standards, and they are not influenced by the Uruguay River, which did not act as an efficient barrier. Keywords

Spatial and temporal divergence of the torquatus species group of the subterranean rodent Ctenomys

“…In a large-scale analysis based on divergence patterns using cyt-b sequences of several non-volant mammals from the Amazon basin, Patton et al (2000) found no evidence to support that the Juruá River, one of the main affluent rivers of the Amazon River, would act as an important barrier, suggesting that large rivers could be more likely to be crossed than expected. In a study based on RAPD (Random Amplified Polymorphic DNA) data, the cricetid rodent Oligoryzomys showed no structure at both banks of the Uruguay River at the proximities of the headwater (Mossi et al, 2014), indicating that it would not be acting as a strong barrier to gene flow. Regarding tuco-tucos, the diversification along but not across rivers demonstrated that C. torquatus may have been able to cross the also large Ibicuí, Vacacaí and Jacuí rivers during a period of dry climate (Roratto et al, 2015).…”

Evaluation of eight protocols for genomic DNA extraction of Hypostomus commersoni Valenciennes, 1836 (Loricariidae: Siluriformes)

“…All DNA was extracted and quantified at the biochemistry and molecular biology laboratory of URI. Seven protocols for DNA extraction were selected from the literature, whose methodologies had previously been described for fish species or whose parameters were similar to those intended to be analyzed in this work, such as the same extraction conditions or target-tissues (Doyle and Doyle, 1987;Medrano et al, 1990;Whitmore et al, 1992;Aljanabi and Martinez, 1997;Faleiro et al, 2003;Barrero et al, 2008;Mossi et al, 2014). An eighth protocol was proposed and evaluated, combining the variables that presented better results in the extraction of H. commersoni DNA in each of the seven tested protocols.…”