Patterns of diversification in islands: A comparative study across three gecko genera in the Socotra Archipelago q Joan Garcia-Porta a,⇑ , Hernán E. Morales b , Elena Gómez-Díaz c , Roberto Sindaco d , Salvador Carranza a a Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta, 37-49, 08003 Barcelona, Spain b School of Biological Sciences, Monash University, Wellington Road, Clayton, Victoria 3800, Australia c Doñana Biological Station (EBD, CSIC), Isla de La Cartuja, Av. Américo Vespucio, s/n. 41092 Sevilla, Spain d Museo Civico di Storia Naturale, via San Francesco di Sales, 88, 10022 Carmagnola (TO), Italy article info Article history: Received 6 August 2015 Revised 19 January 2016 Accepted 10 February 2016 Available online 18 February 2016 Keywords: Reptiles Island Diversification Climate Phenotype abstract In this study we used the complete fauna of geckos of the Socotra Archipelago to test whether the three gecko genera co-occurring in the islands (Pristurus, Hemidactylus and Haemodracon) produced similar out- comes of morphological and climatic diversification. To test this, we produced a time-calibrated tree of 346 geckos including all 16 endemic species of the archipelago and 26 potential close-relatives in the continent. Our dating estimates revealed that most of the diversity of geckos in the archipelago was the consequence of in situ diversification. However not all genera shared similar patterns of diversifica- tion. While in Hemidactylus and Haemodracon this involved great differences in body size and low levels of climatic diversification (mostly involving sympatric distributions), an opposite pattern appeared in Pristurus in which most of the diversification involved shifts in climatic envelopes (mostly involving allopatric and parapatric distributions) but almost no size differentiation. Consistently with this, Pristurus was the only genus in which rates of size diversification in islands were substantially lower than in the continent. This illustrates how different groups can greatly differ in their patterns of intra-island diversification and highlights the importance of taxon-dependent factors at determining different patterns of diversification in the same insular context. Ó 2016 Elsevier Inc. All rights reserved. 1. Introduction One of the most typical outcomes of intra-island diversification is the emergence of adaptive radiations, usually driven by resource partitioning among closely related species coexisting in the same island (Losos and Ricklefs, 2009; Schluter, 2000). In these cases, disruptive selection on resource use traits often leads to the exam- ples of extreme morphological diversification so often observed in islands (Schluter, 2000). Yet, evidence shows that not all groups radiating in insular environments produce high levels of phenotypic diversification (Rundell and Price, 2009). Indeed, phenotypic divergence may not necessarily be the outcome when diversification, instead of involving the partitioning among local resources (or a-niche diversification), takes place across different climatic envelopes (or b-niche diversification), typically involving parapatric or allopatric scenarios (Ackerly et al., 2006). This would allow the accommodation in the same island of multiple species with similar phenotypes and non-overlapping distributions (Harmon et al., 2008; Rundell and Price, 2009). A number of factors may determine whether groups take the path of diversifying at the small scales (typically involving pheno- typic differentiation) and/or at large scales (across different climatic envelopes). On one hand, the physical features of islands provide different patterns of environmental heterogeneity, which in turn can determine different extents of resource partitioning and climatic differentiation. For instance, as island area is often correlated with the diversity of vegetation, islands with different areas will likely provide different opportunities for microhabitat specialization (Losos and Parent, 2009). Moreover, different lengths of the altitudinal gradient in islands will obviously deter- mine different opportunities for altitudinal diversification (Whittaker et al., 2008). On the other hand, physiological or morphological constrains in the insular groups may also lead to different climatic or phenotypic evolvabilities (i.e. the ability to evolve into different phenotypes or into different climatic envelopes), which can be translated into var- ious degrees of climatic or phenotypic differentiation. For instance, http://dx.doi.org/10.1016/j.ympev.2016.02.007 1055-7903/Ó 2016 Elsevier Inc. All rights reserved. q This paper was edited by the Associate Editor J.A. Schulte. ⇑ Corresponding author. E-mail address: j.garcia-porta@ibe.upf-csic.es (J. Garcia-Porta). Molecular Phylogenetics and Evolution 98 (2016) 288–299 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev