Speciation with gene flow in whiptail lizards from a Neotropical xeric biome

Abstract

Two main hypotheses have been proposed to explain the diversification of the Caatinga biota. The riverine barrier hypothesis (RBH) claims that the São Francisco River (SFR) is a major biogeographic barrier to gene flow. The Pleistocene climatic fluctuation hypothesis (PCH) states that gene flow, geographic genetic structure and demographic signatures on endemic Caatinga taxa were influenced by Quaternary climate fluctuation cycles. Herein, we analyse genetic diversity and structure, phylogeographic history, and diversification of a widespread Caatinga lizard (Cnemidophorus ocellifer) based on large geographical sampling for multiple loci to test the predictions derived from the RBH and PCH. We inferred two well-delimited lineages (Northeast and Southwest) that have diverged along the Cerrado-Caatinga border during the Mid-Late Miocene (6-14 Ma) despite the presence of gene flow. We reject both major hypotheses proposed to explain diversification in the Caatinga. Surprisingly, our results revealed a striking complex diversification pattern where the Northeast lineage originated as a founder effect from a few individuals located along the edge of the Southwest lineage that eventually expanded throughout the Caatinga. The Southwest lineage is more diverse, older and associated with the Cerrado-Caatinga boundaries. Finally, we suggest that C. ocellifer from the Caatinga is composed of two distinct species. Our data support speciation in the presence of gene flow and highlight the role of environmental gradients in the diversification process.

Phylogeography of Muller's termite frog suggests the vicariant role of the Central Brazilian Plateau

“…Carnaval, Hickerson, Haddad, Rodrigues, & Moritz, ; Fitzpatrick, Brasileiro, Haddad, & Zamudio, ; Grazziotin, Monzel, Echeverrigaray, & Bonatto, ), they seem to have played a limited role on DOF species (e.g. Oliveira et al., ; Santos, Nogueira, Giugliano, Colli, & Riddle, ; Werneck et al., ). Our data suggest geographic isolation in the Neogene as the main driver of speciation, yet recent Pleistocene climatic events likely shaped diversity at a shallower evolutionary level.…”

“…Domingos et al., ; Giugliano et al., ; Prado, Haddad, & Zamudio, ; Werneck et al., ), riverine barriers (e.g. Nascimento et al., ; Passoni, Benozzati, & Rodrigues, ; Werneck et al., ) and/or environmental gradients (da Fonseca et al., ; Oliveira et al., ; Werneck et al., ). Although most phylogeographic studies in South America evoke the Pleistocene refuge hypothesis (Haffer, ) as the main driving force for speciation (Turchetto‐Zolet, Pinheiro, Salgueiro, & Palma‐Silva, ), Quaternary climatic fluctuations seem to have played a secondary role in the DOF, mainly influencing demographic changes of taxa through time (e.g.…”

Diversity of teiid lizards from Gran Chaco and Western Cerrado (Squamata: Teiidae)

“…While many species of Ameivula have been described in the last years (Arias et al., ,; Arias, de Carvalho, et al., ; Arias, Teixeira, et al., ; Rocha, Araujo, Vrcibradic, & Da Costa, ; Rocha, Bergallo, & Peccininiseale, ; Silva & Ávila‐Pires, ), few studies have examined the phylogenetic relationship within the genus due to a restricted taxonomic sampling (Giugliano, ; Goicoechea et al., ; Harvey et al., ; Oliveira et al., ; Pyron, Burbrink, & Wiens, ). Our phylogenetic hypothesis of Ameivula includes all currently recognised species ( A. abalosi , A. cipoensis , A. confusioniba , A. jalapensis , A. nigrigula , A. mumbuca , A .…”

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“…Upper 97.5% Quantile ¼ the 97.5 th percentile of the distribution of the correlation coeficient with randomized data. may lead to divergence in functionally important traits owing to differential selection in contrasting environments (Smith et al 1997, Doebeli and Dieckmann 2003, Milá et al 2007, McCormack et al 2008, Oliveira et al 2015. Studies examining variation in morphological traits and in multiple loci across the genome would shed further light on the role that environmental variation along the MRV may have in driving phenotypic and genetic divergence among populations.…”

“…Although geographic isolation by physical barriers likely accounts for a large proportion of speciation events in tropical forest organisms (Moritz et al 2000, natural selection in contrasting environments in the absence of physical isolation also might drive speciation and contribute to the buildup of tropical biodiversity (Moritz et al 2000). However, studies examining the relative roles of physical and geographical barriers as drivers of population differentiation and speciation are scarce (Smith et al 1997, Milá et al 2009, Oliveira et al 2015, Weir et al 2015.…”