Diversification and species limits in two genera of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae) revealed by combined molecular and cytogenetic approaches

• Autor(a) principal: Di-Nizo, Camilla Bruno
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: http://www.teses.usp.br/teses/disponiveis/41/41131/tde-26062018-084004/
• topic: Cerradomys; Cerradomys; Chromosomal evolution; Citotaxonomia; Cytotaxonomy; Delimitação de espécies; Evolução cromossômica; Filogenia molecular; Molecular phylogeny; Oligoryzomys; Oligoryzomys; Species delimitation

In this work, the integrative taxonomy approach was performed to understand species limits and patterns of diversification in two genera of orizomyine rodents (Cerradomys and Oligoryzomys). Therefore, molecular markers with distinct evolutionary rates were used with different approaches (phylogeny, coalescent-based species delimitation, DNA barcoding, phylogeography, molecular dating). Classic and molecular cytogenetic analyzes were performed, contributing to cytotaxonomy and revealing chromosomal evolution. This work is divided into four chapters, including a brief introduction (Chapter 1). In Chapter 2, the integrative taxonomy approach was used to study the genus Cerradomys, based on cytogenetic and molecular data. The results revealed that cytogenetics is important in the recognition of all described species (cytotaxonomy). Phylogenetic reconstruction showed that internal relationships are well supported, with the exception of C. subflavus and C. goytaca, which are not reciprocally monophyletic. Following the integrative taxonomy, in which species limits are based on the congruence of methods, this work recognizes and reiterates the eight Cerradomys species described so far. We suggest a taxonomic revision in C. langguthi and C. subflavus, since both may represent species-complex or in process of speciation. Times of divergence show that Cerradomys is a recent genus, with speciation events occurred mainly in the Pleistocene. In Chapter 3, classic and molecular cytogenetics (Fluorescence in situ hybridization - FISH with telomeric and Oligoryzomys moojeni probes) were used to study chromosomal evolution in Cerradomys, based on the molecular phylogeny obtained in Chapter 2. Chromosome painting revealed extensive chromosome reshuffling in Cerradomys. Species with the highest diploid numbers showed exclusively telomeric signals whereas interstitial telomeric signals (ITS) were observed in the species with the lowest diploid numbers. Comparisons of chromosome painting with molecular phylogeny data corroborate the hypothesis that ITS, in this case, are remnants of telomeres. Nevertheless, other chromosomal rearrangements were detected with absence of ITS, indicating that these sequences may have been lost in the process of chromosomal breakages, evidencing that there was both retention and loss of ITS along the karyotypic evolution of the genus. In addition, complex rearrangements were detected between the karyotypes of C. goytaca and C. subflavus, reiterating that these two species are distinct, since hybrids probably would not be viable due to meiotic problems. In Chapter 4, aiming to recover the evolutionary history and species limits of Oligoryzomys, molecular phylogeny studies were integrated into cytogenetic data. The genus was monophyletic, but the internal relations had low support. The compilation of phylogenetic, chromosomal data and geographic distribution (interdisciplinarity) was important to understand species boundaries. Four lineages could not be related to any name and may be new species (Oligoryzomys A-D). Oligoryzomys flavescens was recovered paraphyletic in respect to O. fornesi. Oligoryzomys stramineus, O. microtis and O. nigripes were recovered in two well-structured clades each. In the case of the last two species, the subclades are probably related to exclusive karyotypes. In O. microtis, one subclade is composed of samples from the western Amazon region and the other with samples distributed in southern Amazon region, transition with Cerrado (2n=64, FN=64). In O. nigripes, one of the clades is composed of specimens from northeastern Brazil (2n=62, FN=78) and the other from central-south-southeast Brazil, Argentina, Paraguay and Uruguay (2n=62, FN=80-82). Phylogeographic results corroborate phylogenetic and cytogenetic data, revealing two distinctive phylogroups, consistent with incipient species. Chromosome data corroborate previous work and could be associated to the following names: O. mattogrossae, O. moojeni, O. chacoensis, O. stramineus, O. nigripes and O. flavescens, although the last two species should be reassessed. In addition, an undescribed karyotype is being reported for Oligoryzomys aff. utiaritensis (2n=70, FN=72), as well as new records in Brazil for four species. We suggest a taxonomic revision in O. microtis, O. flavescens and O. nigripes, as these species probably represent incipient or species-complex. In addition, samples related to Oligoryzomys aff. delicatus, Oligoryzomys aff. chacoensis, Oligoryzomys aff. rupestris and Oligoryzomys aff. Utiaritensis should be evaluated morphologically to confirm their identities. The results of this work corroborate the importance of interdisciplinary studies, since the rates of evolution differ according to each character