Evidence for the Pleistocene Arc Hypothesis from genome‐wide SNPs in a Neotropical dry forest specialist, the Rufous‐fronted Thornbird (Furnariidae: Phacellodomus rufifrons)

Abstract

South American dry forests have a complex and poorly understood biogeographic history. Based on the fragmented distribution of many Neotropical dry forest species, it has been suggested that this biome was more widely distributed and contiguous under drier climate conditions in the Pleistocene. To test this scenario, known as the Pleistocene Arc Hypothesis, we studied the phylogeography of the Rufous‐fronted Thornbird (Phacellodomus rufifrons), a widespread dry forest bird with a disjunct distribution closely matching that of the biome itself. We sequenced mtDNA and used ddRADseq to sample 7,167 genome‐wide single‐nucleotide polymorphisms from 74 P. rufifrons individuals across its range. We found low genetic differentiation over two prominent geographic breaks — particularly across a 1,000 km gap between populations in Bolivia and Northern Peru. Using demographic analyses of the joint site frequency spectrum, we found evidence of recent divergence without subsequent gene flow across those breaks. By contrast, parapatric morphologically distinct populations in northeastern Brazil show high genetic divergence with evidence of recent gene flow. These results, in combination with our paleoclimate species distribution modelling, support the idea that currently disjunct patches of dry forest were more connected in the recent past, probably during the Middle and Late Pleistocene. This notion fits the major predictions of the Pleistocene Arc Hypothesis and illustrates the importance of comprehensive genomic and geographic sampling for examining biogeographic and evolutionary questions in complex ecosystems like Neotropical dry forests.

Incorporating topological and age uncertainty into event-based biogeography supports paleo-islands in Galapagos and ancient connections among Neotropical dry forests

“…Phylogenetic patterns of other organisms, such as birds, support the hypothesis of recent connections among Neotropical dry forests (e.g. Corbett et al 2020). Our data, on the other hand, indicates that dispersal of sand spiders to the Caatinga happened as early as in the Oligocene (Fig.…”

Incorporating Topological and Age Uncertainty into Event-Based Biogeography of Sand Spiders Supports Paleo-Islands in Galapagos and Ancient Connections among Neotropical Dry Forests

“…They compiled detailed evidence that compellingly indicates dry conditions in the region during the Quaternary. Phylogenetic patterns of other organisms, such as birds, support the hypothesis of recent connections among Neotropical dry forests (e.g., [60]). Our data, on the other hand, indicate that dispersal of sand spiders to the Caatinga happened as early as in the Oligocene (Figure 7), with no recent dispersals to other areas.…”

A general scenario to evaluate evolution of grassland birds in the Neotropics

“…Phacellodomus rufifronsk ; Corbett et al . 2020) that have a distribution pattern predicted by the ‘Pleistocene Arc Hypothesis’ (Prado & Gibbs 1993). Some model species used to test the island type connectivity are Anthus lutescens , Leistes militaris and Gallinago paraguaiae due to their non‐migratory habits and strong philopatry.…”

“…Phylogeographical studies on organisms inhabiting grasslands in the Neotropics are still in their infancy (Bates et al 2003, Masello et al 2011, Campagna et al 2012a, 2012b, Lopes et al 2018, Moura et al 2018, Norambuena et al 2018, Lima-Rezende et al 2019, Corbett et al 2020, Rocha et al 2020, Santana et al 2020, limiting our understanding of the potential historical scenarios that characterize these ecosystems as well as the potential processes shaping genetic diversity across taxa. Therefore, new information about the phylogeographical history of taxa that specialize in this type of habitat is crucial to understand the historical and geological processes that have shaped the biodiversity of this biome (Antonelli et al 2010, Brumfield 2012.…”