caa a22 4500 445326069 CHVBK 20180317142721.0 cr unu---uuuuu 170323e20110901xx s 000 0 eng 10.1007/s10914-011-9155-0 doi (NATIONALLICENCE)springer-10.1007/s10914-011-9155-0 Evaluating Diversification Hypotheses in the South American Cricetid Thaptomys nigrita (Lichtenstein, 1829) (Rodentia: Sigmodontinae): An Appraisal of Geographical Variation Based on Different Character Systems [Elektronische Daten] [Jânio Moreira, João de Oliveira] Molecular surveys using mtDNA sequences have been used to identify cryptic species in sigmodontine rodents. However, where sampling is uneven, a critical appraisal of further evidence is pivotal to test whether genetic discontinuity represents different species. In order to investigate geographical variation in the Neotropical rodent Thaptomys nigrita, we analyzed patterns of morphological variation in qualitative and morphometric data, and compared our results with recent information on karyological and molecular diversity reported for the monotypic genus. Two subtle morphometric groups of populations, corresponding to karyomorphs 2n = 50 and 2n = 52, were revealed, but no qualitative aspect of craniodental morphology unambiguously distinguished them. A positive and significant association between geographical and both morphological and genetic distances suggest that the distinction between the two groups of population follows an isolation by distance model. This result, coupled with phylogeographic and karyotypic breaks coincident to a sampling gap extending for 540km, and with the low phylogenetic resolution of molecular clades, does not allow rejecting the hypothesis that the divergent samples constitute polymorphic populations of a widely distributed species. We discuss possible determinants of these patterns and emphasize the need for an integrative approach in future efforts to disclose the evolutionary relationships of small mammals in situations of uneven sampling. Springer Science+Business Media, LLC, 2011 Speciation nationallicence Morphometrics nationallicence Atlantic Forest nationallicence Mammals nationallicence Isolation by distance nationallicence Uneven sampling nationallicence Moreira Jânio Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/UFRJ, Quinta da Boa Vista s/n, CEP 20940-040, São Cristovão, Rio de Janeiro/RJ, Brazil aut de Oliveira João Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/UFRJ, Quinta da Boa Vista s/n, CEP 20940-040, São Cristovão, Rio de Janeiro/RJ, Brazil aut Journal of Mammalian Evolution Springer US; http://www.springer-ny.com 18/3(2011-09-01), 201-214 1064-7554 18:3<201 2011 18 10914 https://doi.org/10.1007/s10914-011-9155-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10914-011-9155-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Moreira Jânio Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/UFRJ, Quinta da Boa Vista s/n, CEP 20940-040, São Cristovão, Rio de Janeiro/RJ, Brazil aut NATIONALLICENCE 700 1- de Oliveira João Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/UFRJ, Quinta da Boa Vista s/n, CEP 20940-040, São Cristovão, Rio de Janeiro/RJ, Brazil aut NATIONALLICENCE 773 0- Journal of Mammalian Evolution Springer US; http://www.springer-ny.com 18/3(2011-09-01), 201-214 1064-7554 18:3<201 2011 18 10914 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer