A comparative phylogenomic analysis of birds reveals heterogeneous differentiation processes among Neotropical Savannas

The main objective of this study is to evaluate biogeographic hypotheses
of diversification and connection between isolated savannas north
(Amazonian savannas) and south (Cerrado core) of the Amazon River. To
achieve our goal, we employed genomic markers (genotyping by sequencing)
to evaluate the genetic structure, population phylogenetic relationships,
and historical range shifts of four Neotropical passerines with
peri-Atlantic distributions: the Narrow-billed Woodcreeper (Lepidocolaptes
angustirostris), the Plain-crested Elaenia (Elaenia cristata), the
Grassland Sparrow (Ammodramus humeralis), and the White-banded Tanager
(Neothraupis fasciata). The population genetic analyses indicated that
landscape (e.g., geographic distance, landscape resistance, and percentage
of tree cover) and climate metrics explained divergence among populations
in most species, but without indicating a differential role between
current and historical factors. Our results did not fully support the
hypothesis that isolated populations at Amazonian savannas have been
recently derived from the Cerrado core domain. Intraspecific phylogenies
and gene flow analyses supported multiple routes of connection between the
Cerrado and Amazonian savannas, rejecting the hypothesis that the Atlantic
corridor explains the peri-Atlantic distribution. Our results reveal that
the biogeographic history of the region is complex and cannot be explained
by simple vicariant models.