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

DARÍO A. LIJTMAER; BELÉN BUKOWSKI; PABLO D. LAVINIA; AGUSTIN IVAN CASALE; PABLO FRACAS; LEONARDO CAMPAGNA; PABLO L. TUBARO

London

Congreso; AOS & SCO-SOC 2023; 2023

AOS & SCO?SOC

Glacial cycles have been a key driver of speciation in the Nearctic, but they had amilder effect in most of the Neotropics. We are studying their relevance in thetemperate south of South America at different geographic and taxonomic scales. Theanalysis of 235 avian sister species pairs showed that the Andean-Patagonian regionhas a higher proportion of young species (i.e. originated in the Pleistocene) than therest of the Neotropics, suggesting a relevant effect of glaciations. Detailed analyses ofthe Southern Lapwing (Vanellus chilensis), the Rufous-collared Sparrow (Zonotrichiacapensis) and the House Wren (Troglodytes aedon) were consistent with a significantrole of glaciations. Lineages restricted to Patagonia were found in the three species,although with differences in the timing of their separation. In addition to geneticdifferences, in the Southern Lapwing and the Rufous-collared Sparrow the Patagonianlineages differ in morphology and/or song. In the latter, in fact, the recently originatedPatagonian subspecies is the most differentiated in coloration, a consequence ofdifferences in a single genomic area that contains ST5, a gene involved in theregulation of melanogenesis. In the House Wren, the colonization of the MalvinasIslands from Patagonia and the lack of further gene flow with the continent led tospeciation in the insular population, originating T. cobbii. In spite of these differencesamong species, northward postglacial expansions from Patagonia led to secondarycontact in the three of them, promoting gene flow and intermediate color or vocaltraits. The results of this study highlight the relevance of glaciations for aviandiversification and speciation in southern South America.