A comparative genomics approach to understand historical connections among Neotropical savannas

CÁSSIA ALVES LIMA-REZENDE; GUSCATVO CABANNE; AMANDA VAZ ROCHA; MARTIN CARBONI; RENATO CAPARROZ; ROBERT ZINK

CABA

Congreso; Evolution; 2021

ASN/SSB/SSE

Neotropical open biomes are distributed along two major blocks of savannas separated by the Amazon Forest. Notwithstanding being currently geographically isolated, many taxa with different levels of habitat specialization are shared by south (e.g., Cerrado) and northern blocks (e.g., Amazonian savannas; AmSavs), indicating that these savannas were linked in the past through open vegetation corridors (East Amazonia, Central Amazonia, and West Amazonia routes). Here we used four co-distributed open-habitat passerines (Lepidocolaptes angustirostris, Elaenia cristata, Ammodramus humeralis, and Neothraupis fasciata) to address if (1) Is there a unique biogeographic history for taxa shared between the Cerrado and Amazonian savannas, (2) which are the connection routes between these savannas, and (3) does habitat specialization impact on the population genetic structure? We used genomic datasets (> 4,542 SNPs) to investigate the genetic structure (FST, PCA, and STRUCTURE), population history (SNAPP trees and GPhoCS), and gene flow (GPhoCS and EEMS) of the model species. Our results indicated a weak genetic structure with no congruent phylogeographic breaks among the model species. Tree topologies supported both Cerrado populations as a monophyletic or paraphyletic clade, and recent and asynchronous divergence indicating a Quaternary population dynamic. Therefore, we found no evidence of a unique biogeographic history for these taxa shared between the Cerrado and Amazonian savannas. Gene flow estimates supported all proposed connections between Amazonian savannas and Cerrado, with no support for the use of a single corridor by each species. The significant gene flow and heterogeneity in the divergence times suggest cyclic occurrence of these connections. Although it was expected that specialist species tend to have deeper phylogeographic structure when compared to generalist species, our results do not support this hypothesis. Finally, our results revealed a complex evolutionary history and supported the hypothesis of Quaternary connections between the northern and southern blocks of South American tropical savannas.