Rapid increase in genetic diversity in an endemic Patagonian tuco-tuco following a recent volcanic eruption

Genomic data reveal a loss of diversity in two species of tuco-tucos (genus Ctenomys) following a volcanic eruption

“…Because these results are based on analyses of a large number of putatively neutral markers distributed throughout the genome, we believe that our findings are indicative of the impact of the eruption on genetic variation in the study animals. Intriguingly, the decrease in genetic variation reported here for C. sociabilis contradicts previous findings regarding the impacts of the Puyehue-Cordón Caulle eruption; our prior analyses based on a much more limited suite of microsatellite loci 16 had revealed an increase in post-eruption genetic variation in the focal study population for this species. This difference in outcomes raises intriguing questions regarding the abilities of different types of molecular markers, including associated differences in numbers of loci surveyed, to detect the genetic consequences of recent demographic changes.…”

“…Our results indicate that in both C. sociabilis and C. haigi the reduction in population size documented immediately following the 2011 eruption of the Puyehue-Cordón Caulle volcanic complex 16 was associated with a decrease in genetic variation, as revealed by measures of mean heterozygosity across the multiple loci examined. In the more extensively sampled C. sociabilis , this decrease in genetic variation was evident throughout the focal population, with no apparent differences in response to the eruption based on the sex of the animals or the number of burrow systems sampled.…”

“…To explore the potential impacts of demographic processes on post-eruption genetic variation in our study populations, we conducted a series of simulations. First, to quantify the expected effects of drift resulting from post-eruption declines in population size, we simulated an approximately 50% reduction in each of our pre-eruption study populations; this level of decline was largely consistent with that observed for C. sociabilis immediately following the 2011 eruption 16 . Specifically, we randomly designated 50% of individuals in each pre-eruption sample as survivors, after which we calculated heterozygosity for both the entire pre-eruption population and for the “surviving” post-eruption population.…”

“…The colonial tuco-tuco ( Ctenomys sociabilis ) and the parapatric Patagonian tuco-tuco ( C. haigi ) have been the subjects of extensive behavioral, ecological, demographic, and genetic research, including comparative analyses of genetic variation over multiple spatial and temporal scales 11 – 15 . In 2011, both species were significantly affected by the eruption of the Puyehue-Cordón Caulle volcanic complex in southern Chile, resulting in deceases in population density of ~40% for C. sociabilis and ~25% for C. haigi 16 and providing a rare opportunity to compare directly levels of genetic variation before and after a natural population decline. Notably, previous analyses based on microsatellite markers 16 suggested that this event was associated with a significant post-eruption increase in genetic variation in C. sociabilis but not in C. haigi .…”

“…In 2011, both species were significantly affected by the eruption of the Puyehue-Cordón Caulle volcanic complex in southern Chile, resulting in deceases in population density of ~40% for C. sociabilis and ~25% for C. haigi 16 and providing a rare opportunity to compare directly levels of genetic variation before and after a natural population decline. Notably, previous analyses based on microsatellite markers 16 suggested that this event was associated with a significant post-eruption increase in genetic variation in C. sociabilis but not in C. haigi .…”