Adaptive signal coloration maintained in the face of gene flow in a Hispaniolan Anolis Lizard

Abstract

BackgroundStudies of geographic variation can provide insight into the evolutionary processes involved in the early stages of biological diversification. In particular, multiple, replicated cases of geographic trait divergence present a powerful approach to study how patterns of introgression and adaptive divergence can vary with geographic space and time. In this study, we conduct replicated, fine-scaled molecular genetic analyses of striking geographic dewlap color variation of a Hispaniolan Anolis lizard, Anolis distichus, to investigate whether adaptive trait divergence is consistently associated with speciation, whereby genetic divergence is observed with neutral markers, or whether locally adapted traits are maintained in the face of continued gene flow.ResultsWe find instances where shifts in adaptive dewlap coloration across short geographic distances are associated with reproductive isolation as well as maintained in the face of gene flow, suggesting the importance of both processes in maintaining geographic dewlap variation.ConclusionOur study suggests that adaptive dewlap color differences are maintained under strong divergent natural selection, but this divergence does not necessarily lead to anole speciation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0763-4) contains supplementary material, which is available to authorized users.

Genomic Signatures of Historical Allopatry and Ecological Divergence in an Island Lizard

“…More recently, there have been clear indications that divergence with gene flow due to ecological differences has been a major diversifying force and led to the evolution of different phenotypes (Rundle and Nosil 2005; Hohenlohe et al. 2010; Ng et al. 2016).…”

A genomic assessment of species boundaries and hybridization in a group of highly polymorphic anoles (distichusspecies complex)

“…Our third set of 59 samples was designed to assess genetic divergence and hybridization between A. d. ignigularis and A. d. dominicensis across a hybrid zone at the base of Samaná Peninsula in the northeastern Dominican Republic. Previous work along this zone indicates abrupt phenotypic and genetic divergence, albeit with considerably shallower genetic differentiation than the transect between A. d. ignigularis and A. d. ravitergum (Ng & Glor, ; Ng et al., ; Table , Set 3).…”

“…Our second set of 92 individuals was designed to assess genetic divergence and hybridization between A. d. ignigularis and A. d. ravitergum across a hybrid zone along the Baní River in the south‐central Dominican Republic. Previous work has suggested abrupt phenotypic and genetic differentiation across a narrow hybrid zone (<5 km), with limited evidence for widespread gene flow or introgression (Ng & Glor, ; Ng et al., ; Table , Set 2).…”

“…Meanwhile, mitochondrial DNA (mtDNA) sequence data suggested that each of the subspecies found in the Dominican Republic form distinct and deeply divergent clades, with the exception of the widespread subspecies A. d. dominicensis , which is associated with multiple mtDNA clades (Glor & Laport, ). Fine‐scale studies of contact zones between pairs of subspecies involving phenotypic, mitochondrial, and microsatellite data have uncovered evidence for abrupt phenotypic and genetic divergence along narrow hybrid zones, but also evidence for extensive introgression and relatively shallow genetic differentiation (Ng & Glor, ; Ng, Ossip‐Klein & Glor, ). Multilocus phylogenetic analyses have found that while most subspecies of A. distichus are genetically distinct, these differences were mostly restricted to mtDNA, and several subspecies were not monophyletic (Geneva et al., ).…”

“…We then use AFLP genome scans on a finer geographic scale to test Ng et al. 's () prediction that two pairs of subspecies characterized by different dewlap color are genetically distinct and experiencing limited gene flow where they come into contact. With our genomic perspective, we also test the hypothesis that dewlap color has diverged repeatedly within and among populations of A. distichus .…”