Diversity of neotropical rodents (Rodentia: Sciuridae, Cricetidae, Echimyidae): origin, evolution and biogeography

Abstract

The biological sciences are facing several challenges and one of the most important has been to describe, quantify and understand biological diversity and the mechanisms that generate and maintain the diversity. More intriguing, it has been to evaluate why in some lineages high species richness in accompanied by ecomorphological disparity while in others not. The backbone of this proposal is to study the patterns and process of diversification that explain such differences, using as a biological model an impressive group of mammals of the Neotropical region, the rodents of the families Sciuridae, Cricetidae and Echimyidae (squirrels, rats and spiny-rats). These rodents represent good models as: 1) they are relatively easy to sample, both in the field and collections, and will provide enough sample size for all populations modelling analysis; 2) these three groups represent distinct evolutionary lineages (although being a monophyletic group), with distinct times of arrival in South America and apparently different levels of diversification; 3) several species of each family exhibit sympatric distributions, but with distinct ecologies and life-histories. Although widespread throughout the Neotropical region, rodents and Amazon conform a unique combination, as the Amazon forest is presumed to assemble the most diverse assemblages of these rodents and the most complex scenarios of biotic diversification, but for these groups this still need to be more adequately studied and tested. Consequently, most sampling effort is planned to occur in this region, from where we already have available important samples fir these groups. The patterns and processes of diversification will be studied through innovative concepts and methods, such as comparative phylogeography and coalescent species delimitation approach through the employment of genomic and geometric morphometric analytical methods on a microevolutionary perspective, and time and ancestral area estimates coupled to diversification analyses on a macroevolutionary approach. The combination of the three characteristics of rodents with the Amazonian as the main study area fulfill the theoretical and analytical requirements and premises of qualitative and quantitative methods that will be employed on this proposal.Therefore, our objectives are to describe, quantify and understand biological diversity and the mechanisms that generate and maintain the diversity. (AU)