The role of glacial cycles on the diversification and speciation of the birds of southern South America

LIJTMAER, DARÍO A.; BUKOWSKI, BELÉN; LAVINIA, PABLO D.; CASALE, AGUSTÍN I.; FRACAS, PABLO A.; CAMPAGNA, LEONARDO; TUBARO, PABLO L.

London

Congreso; AOS & SCO?SOC 2023; 2023

American Ornithological Society (EEUU) y Society of Canadian Ornithologists

Glacial cycles have been a key driver of speciation in the Nearctic, but they had a milder effect in most of the Neotropics. We are studying their relevance in the temperate south of South America at different geographic and taxonomic scales. The analysis of 235 avian sister species pairs showed that the Andean-Patagonian region has a higher proportion of young species (i.e. originated in the Pleistocene) than the rest of the Neotropics, suggesting a relevant effect of glaciations. Detailed analyses of the Southern Lapwing (Vanellus chilensis), the Rufous-collared Sparrow (Zonotrichia capensis) and the House Wren (Troglodytes aedon) were consistent with a significant role of glaciations. Lineages restricted to Patagonia were found in the three species, although with differences in the timing of their separation. In addition to genetic differences, in the Southern Lapwing and the Rufous-collared Sparrow the Patagonian lineages differ in morphology and/or song. In the latter, in fact, the recently originated Patagonian subspecies is the most differentiated in coloration, a consequence of differences in a single genomic area that contains ST5, a gene involved in the regulation of melanogenesis. In the House Wren, the colonization of the Malvinas Islands from Patagonia and the lack of further gene flow with the continent led to speciation in the insular population, originating T. cobbii. In spite of these differences among species, northward postglacial expansions from Patagonia led to secondary contact in the three of them, promoting gene flow and intermediate color or vocal traits. The results of this study highlight the relevance of glaciations for avian diversification and speciation in southern South America.