The influence of the forest corridors to the north of the Andes on the
diversification of the Bright-rumped Attila, Attila spadiceus
(Passeriformes, Tyrannidae), during the climatic oscillations of the
middle Pleistocene
Abstract
Aim: This study aims to enhance our understanding of the temporal and
spatial proceses scales governing the taxonomic diversification of
Neotropical birds with Trans- and Cis-Andean populations. Location:
Central America and South America. Taxon: Attila spadiceus
(Bright-rumped Attila). Methods: Through a multilocus analysis of the
mitochondrial (CytB and ND2) and nuclear genes (I7BF, I5BF, and G3PDH)
of 41 samples representing six subspecies, we describe the existing
molecular lineages of A. spadiceus, and estimate their demographic
dynamics. We also modeled the climatic niche of the species. Results:
The analysis confirms a relatively recent divergence of the Trans- and
Cis-Andean lineages, at approximately 0.25 million years ago (Ma). The
niche modeling supports the existence of a dynamic scenario of the
expansion and retraction of forest corridors in northwestern South
America during the last glaciation. This suggests that the earlier
orogenesis of the Andes was not a primary determinant of this dichotomy.
Additionally, the analysis of population dynamics indicated a trend of
increasing population size starting at 0.05 Ma for both lineages. Main
Conclusions: Our findings highlight the significance of Pleistocene
Forest corridors north of the Andes as the key factor maintaining
communication before the separation of the lineages, likely associated
with the retraction of this forest. We highlight the absence of any
significant differentiation between the disjunct Amazonian and Atlantic
Forest populations, both part of the Cis-Andean lineage. The
phylogeographic profile of A. spadiceus diverges from the patterns
observed in other Neotropical birds, which emphasizes the need for
further research on the role of the forest corridors of the northern
Andes as drivers of diversification, to provide comprehensive insights
into the processes that led to the formation of the region’s present-day
avian diversity.