Abstract
We present new karyotype records for six Proechimys species from the Brazilian Amazon. P. echinothrix from the region of Purus River had 2n = 32 chromosomes and a FN = 58, while P. cuvieri from the region of the Japurá River presented 2n = 28 and FN = 46. All individuals presented hybridization with an 18S rDNA probe in a single chromosome pair, with the exception of P. cuvieri from the Japurá region, which presented a third signal in one of the homologs of pair 1. No ITS were found in any of the individuals. Our data supports the hypothesis that the P. cuvieri population from the Japurá Basin and P. echinothrix from the lower Purus are new taxonomic entities. Our data expand the geographic distribution of the cytotype (2n = 40, FN = 54) described for P. gardneri from the Madeira River, and the cytotype (2n = 46, FN = 50), described for P. guyannensis, as well as the recently-described cytotype of P. goeldii (2n = 16, FN = 14). No clear pattern of chromosomal evolution has yet been defined in Proechimys, despite the considerable karyotypic diversity of the genus.
Highlights
The Neotropical rodents of the family Echimyidae are considered the most diverse of the infraorder Hystricognathi, in terms of their taxonomy, and their ecology, morphology, and adaptations (Araújo et al, 2014)
We extended the known geographic distributions of P. gardneri, P. guyannensis and P. echinothrix by surveying areas not previously sampled for these species
Recent cytogenetic studies have provided increasingly valuable markers for the understanding of the evolution of the genus, given that, while the diploid number does not vary, there are meaningful differences in the chromosome morphology, which are reflected in the fundamental number (FN), and in the position of the other markers in the karyotype, as in the location of the nucleolus organizer region (NOR)
Summary
The Neotropical rodents of the family Echimyidae are considered the most diverse of the infraorder Hystricognathi, in terms of their taxonomy, and their ecology, morphology, and adaptations (Araújo et al, 2014). The Echimyidae, which includes approximately 90 species in 19 genera (Woods and Kilpatrick, 2005; Patton and Leite, 2015), is a prime example of major adaptive radiations in the Hystricognathi (Fabre et al, 2012). A number of studies have shown that non-codifying repetitive DNA sequences play a fundamental role in cell maintenance, and are involved in regulatory mechanisms that determine gene expression. These sequences may result in phenotypic changes, as well as being involved in the speciation process through the evolution of the host genome (Kazazian, 2004; Martins, 2007; Vitte et al, 2014; Zeigler, 2014). The physical-chromosomal mapping of repetitive sequences may provide important insights into the structure of the genome and generate chromosomal markers, which may be extremely valuable for evolutionary studies, including the identification of specific chromosomes and rearrangements, and in particular the identification of sex chromosomes (Martins, 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
