Digging for molecular variation in low polymorphic species: an analysis of philopatry in the endangered hooded grebes Podiceps gallardoi

MAHLER, B.; MAZZONI, C.

Berlin

Jornada; Fifth Genomics Symposium; 2018

The hooded grebe Podiceps gallardoi is a critically endangered endemic bird of the southernmost part of continental Argentina. The species has reproductive conditions restricted to lakes of basaltic Preandean plateus, which led to its discovery only in 1974. Since then, global population dropped 80% leaving about 800 individuals. Identified threats include climate change, invasive American minks, and introduced trouts. In winter, hooded grebes migrate towards the estuaries of the Atlantic Ocean returning to the plateaus in spring. A relatively constant number of individuals is found at each plateau during successive breeding seasons, suggesting that Hooded Grebes are phylopatric to breeding plateaus. Using a ddRADseq-derived approach known as 3RAD, we analyzed the population structuring among three different plateaus separated by approx. 200 km from each other (Lago Buenos Aires-Strobel-Siberia). On the one hand, the extremely low variation found in Hooded Grebes has helped achieving a highly reproducible 3RAD dataset. On the other hand, the low number of SNPs across populations demanded a careful control of each methodological step, both in the lab and analytical levels, in order to reach high overlapping of loci with satisfactory coverage among individuals. The resulting dataset generated consisting SNPs across different analytical pipelines and is now being used for downstream population analyses.