Origin and in situ diversification in Hemidactylus geckos of the Socotra Archipelago

Abstract

The Socotra Archipelago is an ancient continental fragment of Gondwanan origin and one of the most isolated landforms on Earth and a biodiversity hot spot. Yet, the biogeography and evolutionary history of its endemic fauna still remain largely overlooked. We investigate the origin, tempo and mode of diversification in the Hemidactylus geckos of the Socotra Archipelago. Concatenated and multilocus species coalescent analyses of Hemidactylus from Arabia and North Africa indicate that the Hemidactylus from Socotra do not form a monophyletic group and branch as three independent and well‐supported clades instead. Both the chronogram inferred using the gene tree approach of BEAST and the age‐calibrated multilocus species tree obtained using *BEAST suggest that the origin of Hemidactylus from Socotra may have involved a first vicariance event that occurred in the Early Miocene, followed by two independent transoceanic dispersal events that occurred more recently, during the Pliocene. Within Socotra, we analysed patterns of genetic diversity, the phylogeography and the demographic history in all seven nonintroduced species of Hemidactylus. Results based on two mitochondrial and two nuclear loci from 144 individuals revealed complex patterns of within‐island diversification and high levels of intra‐species genetic divergence. The interplay of both historical and ecological factors seems to have a role in the speciation process of this group of geckos. Interestingly, the case of H. forbesii and H. oxyrhinus, which inhabit the island of Abd al Kuri with an area of 133 km2, may represent one of the most extreme cases of intra‐island speciation in reptiles ever reported.

Out of Arabia: A Complex Biogeographic History of Multiple Vicariance and Dispersal Events in the Gecko Genus Hemidactylus (Reptilia: Gekkonidae)

“…Originally this clade consisted of only 13 species from Arabia, Socotra, East Africa and the Mediterranean. Additional 24 taxa were added to this clade in later studies [7], [19]–[21], [23], [26]. With the new species revealed in previous [19], [23] and this study, the Arid clade of Hemidactylus accounts for 35.4% out of a total of 130 recognized Hemidactylus species.…”

“…As a result of its wide distribution and high species richness, the genus Hemidactylus represents an excellent model for testing biogeographic, ecological and evolutionary hypotheses, and has therefore become a centre of attention of molecular phylogenetic studies [5]–[7], [14]–[26]. The first comprehensive phylogeny covering about one third of all Hemidactylus species was published by Carranza and Arnold [6].…”

“…Mainland Arabian Hemidactylus have witnessed a substantial increase of described taxa, from 9 to 21 within the last two years [7], [21], [23]. Moreover, recent works from the Levant [23] and the Socotra Archipelago [26] reported the occurrence of several unnamed (or putative) species in the Sinai, Yemen mainland and Socotra, suggesting that the real diversity of the Arabian members of the Arid clade of Hemidactylus is still largely underestimated. In contrast to the relatively high number of recent studies on Arabian Hemidactylus , virtually nothing is known about Northeast African Hemidactylus from a phylogenetic point of view.…”

Microendemicity in the northern Hajar Mountains of Oman and the United Arab Emirates with the description of two new species of geckos of the genusAsaccus(Squamata: Phyllodactylidae)

“…Despite the problems associated with using evolutionary rates from other organisms for time tree calibration, the rates inferred by Carranza & Arnold (2012) and applied here correspond with the rates obtained in other independent studies that used different calibration points and different taxa (Metallinou et al, 2012; Sindaco et al, 2012). Indeed, the rates by Carranza & Arnold (2012) have been applied to several different studies for which reliable internal calibration points based on biogeographic events or fossil evidence do not exist (Gómez-Díaz et al, 2012; Hawlitschek & Glaw, 2013; Metallinou & Carranza, 2013; Milá et al, 2013; Šmíd et al, 2013; Vasconcelos & Carranza, 2014; Metallinou et al, 2015; De Pous et al, 2016; Tamar et al, 2016). Tree nodes were considered strongly supported if they received ML bootstrap values ≥70% and posterior probability (pp) support values ≥0.95 (Wilcox et al, 2002; Huelsenbeck & Rannala, 2004).…”

Sympatric Diversification in the Upper Amazon: A Revision of the Eumaeine Genus Paraspiculatus (Lepidoptera: Lycaenidae)

“…This species complex is the main reason for the original observation of a high incidence of sympatry in the upper Amazon Basin. In situ diversification is usually examined on ecological or physical islands (Simon et al, 2009;Gómez-Díaz et al, 2012;Pante et al, 2012;Blaimer et al, 2015), but perhaps it is also relevant to biogeographic areas. A comprehensive explanation for the high frequency of sympatry in Paraspiculatus would undoubtedly focus on this lineage.…”