A comparative genomics approach to understand historical connections among Neotropical savannas

LIMA REZENDE, CÁSSIA ALVES; CABANNE, GUSTAVO SEBASTIÁN

Conferencia; Evolution Meeting; 2021

Neotropical open biomes are distributed along two major blocks of savannas separated by the AmazonForest. Notwithstanding being currently geographically isolated, many taxa with different levels of habitatspecialization are shared between south (e.g., Cerrado) and northern blocks (e.g., Amazonian savannas;AmSavs), indicating that these savannas were linked in the past. Hypothesized corridors linking these regionsare at: East Amazonia, Central Amazonia, and West Amazonia routes. Here we used genomic analyses offour co-distributed open-habitat passerines ( Lepidocolaptes angustirostris, Elaenia cristata, Ammodramushumeralis, and Neothraupis fasciata) to address if (1) is there a unique biogeographic history for taxa sharedbetween 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 GBS datasets (>4,542 SNPs/species) to investigate the genetic structure (FST, PCA, and STRUCTURE), population history(SNAPP trees and GPhoCS), and gene flow patterns (GPhoCS and EEMS). Our results indicated weakgenetic structures and no congruent phylogeographic breaks among the model species. Tree topologiessupported both Cerrado populations as a monophyletic or paraphyletic group, and recent and asynchronousdivergence indicating a Quaternary population dynamic. Therefore, we found no evidence of a uniquebiogeographic history for the taxa shared between the Cerrado and Amazonian savannas. G ene flowestimates supported all proposed connections between Amazonian savannas and Cerrado, with no support forthe use of a single corridor. The significant gene flow and heterogeneity in the divergence times suggestcyclic occurrence of these connections. Although it was expected that specialist species tend to have deeperphylogeographic structure when compared to generalist species, our results do not support this hypothesis.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 Quaternaryconnections between the northern and southern blocks of South American tropical savannas.