Did paleoenvironmental change drive the loss of genetic diversity in colonial tuco-tucos?

TAKENAKA, RISA; LACEY, EILEEN A.; TAMMONE, MAURO N.

Congreso; 99TH ANNUAL MEETING & CENTENNIAL CELEBRATION OF THE AMERICAN SOCIETY OF MAMMALOGISTS; 2019

Identifying the factors that contribute to pronounced changes in genetic diversity is essential tounderstanding the evolutionary dynamics and conservation needs of natural populations of mammals.Colonial tuco-tucos (Ctenomys sociabilis) are subterranean rodents that are endemic to Neuquén Province,Argentina. Paleogenetic data indicate that although C. sociabilis underwent a significant loss of geneticdiversity ~ 3,000-5,000 ybp, the partially sympatric Patagonian tuco-tuco (C. haigi) did not experience asimilar reduction in variability. Using radiocarbon- dated stratigraphy, paleogenetic variability, and stableisotope signatures, we explored the effects of the following factors on genetic diversity in these species:vulcanism, interspecific competition, and gradual changes in local Holocene environments. Comparisonsof data from three cave deposits in the Limay Valley revealed that the timing and spatial distribution ofgenetic changes in our study species were not consistent with either the volcanic or competitionhypotheses. Carbon isotope signatures from sub-fossil tooth samples revealed significant changes inHolocene food resources consumed by C. haigi but not C. sociabilis. We propose that general changes inenvironmental conditions in the Limay Valley in conjunction with the greater ecological specialization of C.sociabilis led to a significant reduction in availability of suitable habitat for this species but not for C. haigi,with associated demographic impacts contributing to the pronounced historical reduction in geneticvariability in C. sociabilis.