Combining DNA barcodes and genomics to assess if a subtropical river in the Neotropics is acting as a geographic barrier for birds

CAMPAGNA, LEONARDO; GARCÍA, NATALIA C.; LOVETTE, IRBY; LIJTMAER, DARÍO A.; LAVINIA, PABLO D.; DI GIACOMO, ADRIÁN SANTIAGO; KOPUCHIAN, CECILIA; CABANNE, GUSTAVO SEBASTIÁN; TUBARO, PABLO L.

Trondheim

Congreso; 8th International Barcode of Life Conference; 2019

Barcode of Life

The riverine barrier hypothesis proposes that large tropical rivers represent geographic barriers to gene flow for different organisms, leading to population differentiation and eventually, speciation. This hypothesis was first put forward in relation to the Amazon River basin; an area that includes the largest rivers in the Neotropics. Here we asses if the subtropical Paraná-Paraguay Rivers axis in the Del Plata basin, the second in importance in South-America, acts as a barrier for east-west dispersion and gene flow for bird species. Results: We use COI and a reduced representation genomic approach (ddRADseq) to assess genetic differentiation in seven species that have subspecies defined based on morphological differences on either side of these rivers axis. Only one of the species analyzed showed genetic differentiation concordant with the current course of the Paraná-Paraguay Rivers. Another five species show population structure with an East/West split that is not concordant with the current location of rivers, but that coincide broadly with the Parana River paleo-channel; suggesting a role of this river in shaping the observed genetic structure. In one of those species (Cyanocompsa brissonii), the contact zone determined by nuclear loci was displaced towards the west with respect to the COI, morphological and behavioral transition. There was weak population structure in the remaining species, showing no clear association with the rivers. We discuss our results in the context of the geological history of the region, the ecological differences among ecoregions in our study area, and the biology of each species. Significance: This study shows how mitochondrial and genomic data are useful to test classic biogeographic hypotheses, both by showing contrasting and concordant patterns, which should be analyzed in the context of the geological and ecological history of the region.