Systematics, biogeography, and diversification of Scytalopus tapaculos (Rhinocryptidae), an enigmatic radiation of Neotropical montane birds

Abstract

We studied the phylogeny, biogeography, and diversification of suboscine passerines in the genus Scytalopus (Rhinocryptidae), a widespread, species-rich, and taxonomically challenging group of Neotropical birds. We analyzed nuclear (exons, regions flanking ultraconserved elements) and mitochondrial (ND2) DNA sequence data for a taxonomically and geographically comprehensive sample of specimens collected from Costa Rica to Patagonia and Brazil. We found that Scytalopus is a monophyletic group sister to Eugralla and consists of 3 main clades roughly distributed in (1) the Southern Andes, (2) eastern Brazil, and (3) the Tropical Andes and Central America. The clades from the Southern Andes and eastern Brazil are sister to each other. Despite their confusing uniformity in plumage coloration, body shape, and overall appearance, rates of species accumulation through time in Scytalopus since the origin of the clade in the Late Miocene are unusually high compared with those of other birds, suggesting rapid non-adaptive diversification in the group. We attribute this to their limited dispersal abilities making them speciation-prone and their occurrence in a complex landscape with numerous barriers promoting allopatric differentiation. Divergence times among species and downturns in species accumulation rates in recent times suggest that most speciation events in Scytalopus predate climatic oscillations of the Pleistocene. Our analyses identified various cases of strong genetic structure within species and lack of monophyly of taxa, flagging populations which likely merit additional study to clarify their taxonomic status. In particular, detailed analyses of species limits are due in S. parvirostris, S. latrans, S. speluncae, the S. atratus complex, and the Southern Andes clade.

Biogeography of a neotropical songbird radiation reveals similar diversification dynamics between montane and lowland clades

“…Mean diversification rates estimated by BAMM are comparable with those of other rapid radiations in birds such as tanagers, tapaculos and ovenbirds (Furnariidae) (Table S5) (Cadena et al, 2020). Despite the lack of shifts in diversification rates in the BAMM analysis, the LTT shows higher diversification rates in the montane versus lowland clade, both early in the radiation of the genus and more recently, during the early Pleistocene, resulting in slightly higher current montane diversity (Figure 2).…”

“…Mean diversification rates estimated by BAMM are comparable with those of other rapid radiations in birds such as tanagers, tapaculos and ovenbirds (Furnariidae) (Table S5) (Cadena et al, 2020).…”

Ecological drivers of global gradients in avian dispersal inferred from wing morphology

“…refs. 32,35,56,58 ). Even on larger islands, such as Borneo, low dispersal (inferred from low HWI) strongly predicts reduced gene flow and incipient speciation in birds 34 .…”

An Evolutionary Study of Carex Subg. Psyllophorae (Cyperaceae) Sheds Light on a Strikingly Disjunct Distribution in the Southern Hemisphere, With Emphasis on Its Patagonian Diversification

“…Most available phylogeographical studies focusing on plants along South America (SA) have been primarily restricted to the Tropical Andes region (Muellner et al, 2005 ; Marcheli and Gallo, 2006 ; Acosta and Premoli, 2010 ; Table 1 ), while Patagonia remains among the least phylogeographically studied regions of SA despite having been affected more than other areas of the continent by historical environmental changes, both recently and over geological time scales (Rabassa, 2008 ; Sérsic et al, 2011 ). The interest in understanding the historical processes impacting Patagonian biota has been increasing in the last decades, with a special focus on animals (e.g., rodents, Kim et al, 1998 ; lizards, Morando et al, 2004 , 2007 ; Breitman et al, 2012 ; fishes, Cussac et al, 2004 ; Ruzzante et al, 2008 ; birds, Calderón et al, 2014 ; Cadena et al, 2020 ). However, understanding of the evolutionary history and processes of plant diversification in this region has not bloomed until recently (Azpilicueta et al, 2009 ; Jakob et al, 2009 ; Tremetsberger et al, 2009 ; Cosacov et al, 2010 ; Sede et al, 2012 ; Nicola et al, 2014 , 2019 ; Soliani et al, 2015 ; López and Bonasora, 2017 ; Table 1 ).…”