Unveiling the evolutionary history of a widespread passerine (Troglodytes aedon/cobbi species complex) in the southern Neotropics by integrating mitochondrial and genomic data

KOPUCHIAN, CECILIA; TUBARO, PABLO L.; LIJTMAER, DARÍO A.; CAMPAGNA, LEONARDO

Montpellier

Congreso; 2018 Evolution Meeting; 2018

Esuropean Society for the Study of Evolution, Society for the Study of Evolution, American Society of Naturalists, Society of Systematic Biologists

Divergent intraspecific lineages discovered in mitochondrial-based analyses are frequently interpreted as being isolated with limited gene flow. However, nuclear markers are better suited to uncover patterns of gene flow and can be currently easily obtained at large scale using genomic techniques. Here we combine mitochondrial and genomic (ddRADseq) data to study the evolutionary history of the House Wren species complex, Troglodytes aedon and T. cobbi. We focused on the southern cone of South America and included both Continental populations of T. aedon and insular populations of T. cobbi from the Malvinas/Falkland Islands. Mitochondrial (COI) data from around 120 specimens from Argentina, Bolivia and Uruguay revealed the presence of at least 4 continental lineages with up to 5% sequence divergence. These lineages, however, were not clearly geographically structured: only one lineage is present in Patagonia but two or three different lineages are sympatric in other localities in Argentina. The insular population of T. cobbi formed a fifth mitochondrial lineage, sister to that of Patagonia. Our genomic analysis did not differentiate the Continental lineages as clearly as the mitochondria, with the exception of a few birds from the High Andes in Bolivia, suggesting instead high levels of gene flow among lineages and even exposing some cases of mitochondrial introgression. These results suggest the presence of divergent mitochondrial lineages in the Continental southern Neotropics in an otherwise largerly panmictic population. This pattern could have arisen as a result of isolation during glacial periods both within the Continent and between continental and insular populations and posterior secondary contacts with gene flow among Continental lineages. The very large effective population size of this species could have also contributed to the retention of mitochondrial diversity. This study highlights that analyzing nuclear and mitochondrial data together could provide a better understanding of evolutionary history.