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Phylogeography of the subterranean rodent Ctenomys torquatus : an evaluation of the riverine barrier hypothesis
Author(s) -
Roratto Paula Angélica,
Fernandes Fabiano Araújo,
Freitas Thales R. O.
Publication year - 2015
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.12460
Subject(s) - phylogeography , mantel test , biology , range (aeronautics) , population , rodent , ecology , isolation by distance , genetic structure , zoology , genetic variation , phylogenetic tree , genetics , demography , sociology , gene , composite material , materials science
Aim Subterranean rodents of the genus Ctenomys are widespread in open habitats; the collared tuco‐tuco, C. torquatus , has a wide range crossed by large water‐courses. Based on a phylogeographical approach to investigate the riverine barrier hypothesis, we evaluated the strength of a river as a barrier and characterized the effect of large rivers in structuring distinct populations of the collared tuco‐tuco. Location Grasslands of southern Brazil. Methods Sampling included 294 individuals from 33 localities throughout the geographical range of C. torquatus , especially around the main rivers. Phylogeographical patterns were estimated through two mitochondrial DNA sequences (control region and COI ). Additionally, 22 microsatellite loci were surveyed to estimate the effect of rivers on population divergence through the F ST index of genetic differentiation and AMOVA s. Spatial autocorrelation analyses were performed for both molecular markers. Molecular rates of change for mitochondrial DNA were estimated using fossil records and applied to Bayesian demographic analysis to test the relationship with the river geological data. Results Molecular‐clock analysis estimated the time to most recent common ancestor ( TMRCA ) to be c . 200 kyr and indicated a pattern of recent demographic expansion for C. torquatus . Fu's F S neutrality test was significant and negative (−13.7). High and significant F ST and AMOVA among‐population comparisons ( F SC ) revealed highly differentiated populations, although no AMOVA groupings considering rivers as a segregating factor were significant. Spatial autocorrelation analysis revealed that isolation by distance was detected over approximately 200 km. Main conclusions The effect of the river was not proportionally larger from the headwaters to the mouth, and no population differentiation was observed after the later events of dispersal over the river or the formation of a water channel. This finding could result from the recent history of the occupation of C. torquatus in that region, combined with a dry Pleistocene climate and lower river levels.