Abstract
Seven microsatellite loci were used to investigate the genetic variability and structure of six mainland and two island populations of the Neotropical water rat Nectomys squamipes, a South American semi-aquatic rodent species with a wide distribution. High levels of variability were found within mainland populations while island populations were less variable but the more differentiated in respect to allele number and frequency. The time of biological divergence between mainland and island populations coincided with geological data. A significant geographic structure was found in mainland populations (theta = 0.099; rho = 0.086) although the degree of differentiation was relatively low in respect to the distance between surveyed localities (24 to 740 km). Genetic and geographic distances were not positively correlated as previously found with random amplified polymorphic DNA (RAPD) markers. Significant but low genetic differentiation in the mainland and lack of isolation by distance can be explained by large population size and/or recent population expansion. Additionally, the agreement between the age of geologic events (sea level fluctuations) and divergence times for insular populations points to a good reference for molecular clock calibration to associate recent environmental changes and the distribution pattern of small mammals in the Brazilian Atlantic Forest.
Highlights
The Neotropical water rat, Nectomys squamipes (Brants, 1827), is a semi-aquatic rodent species widely distributed along rivers and streams of the Atlantic Forest and Cerrado biomes in Eastern Brazil
One hundred and ten Nectomys squamipes were captured with Sherman or Tomahawk live traps in eight Brazilian localities (Figure 1), six mainland sites at Glicério (GL; n = 26); Fazenda União (FU; n = 8); Sumidouro (SU; n = 18), Tarituba (TA; n = 21) in Rio de Janeiro State; Pedreiras (PD; n = 10) in São Paulo State and Fazenda Canoas (FC; n = 6) in Minas Gerais State and two insular sites Ilha da Marambaia (IM; n = 8) and Ilha Grande (IG; n = 13) in Rio de Janeiro State
No significant linkage disequilibrium was found between any pair of loci either when pooling all populations or when considering each population separately
Summary
The Neotropical water rat, Nectomys squamipes (Brants, 1827), is a semi-aquatic rodent species widely distributed along rivers and streams of the Atlantic Forest and Cerrado biomes in Eastern Brazil. Ecological studies showed that these rodents rarely move farther than 20 m from streams, their home range being restricted to a range of from 200 to 14,808 m2 and 90% of displacements occurring only in the water or along riverbanks (Bergallo, 1995, MV Vieira, personal communication). These rodents rely on a generalist diet and the availability of riverbank habitats seems to be the only factor affecting their distribution that might occur in the proximity of urban areas (Gentile, et al, 2000), their semi-aquatic habits may hinder migration between river basins and across mountain ranges.
Sign-in/Register to view highlights & summary 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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
