The role of vicariance vs. dispersal in shaping genetic patterns in ocellated lizard species in the western Mediterranean

Abstract

The schism between North Africa and Southern Europe caused by the opening of the Strait of Gibraltar and the consequent refilling of the Mediterranean basin at the end of Messinian salinity crisis (MSC), 5.33 million years ago, has been advocated as the main event shaping biogeographical patterns in the western Mediterranean as exemplified by the distribution of species and subspecies and genetic variation within the ocellated lizard group. To reassess the role of the MSC, partial sequences of three mitochondrial DNA genes (cytochrome b, 12S and 16S ribosomal RNA) and two nuclear genes (b-fibrinogen and C-mos) from species of the ocellated lizard group were analysed. Three alternative hypotheses were tested: that divergence was initiated (i) by post-MSC vicariance as the basin filled, (ii) when separate populations established either side of the strait by pre-MSC overseas dispersal, and (iii) by post-MSC overseas dispersal. The pattern and level of divergence detected clearly refute the post-MSC vicariance hypothesis, and support a model of divergence initiated by earlier overseas dispersal. Indeed, our best estimate is that the basal Euro-African divergence predates the MSC event by several million years. The estimated divergence times among the populations in former Miocene Mediterranean islands, the current Betic and Rifian mountains, from adjacent mainland populations suggest overseas dispersal for the former and overland dispersal, or perhaps vicariance, for the latter. These results suggest that the MSC may have played a much less important role in shaping the current western Mediterranean biogeographical patterns than might have been anticipated from the dramatic nature of the episode.

Where are you from, stranger? The enigmatic biogeography of North African pond turtles (Emys orbicularis)

“…In general, the differentiation pattern found for Iberian and North African pond turtles mirrors a common paradigm for North African amphibians and reptiles, with Moroccan populations often being well-differentiated from their eastern Algerian and Tunisian counterparts (e.g., Pleurodeles spp., Veith et al 2004; Hyla meridionalis, Recuero et al 2007;Mauremys leprosa, Fritz et al 2006b;Testudo graeca, Fritz et al 2009b; Chamaeleo chamaeleon, Dimaki et al 2008; Timon spp., Paulo et al 2008;Coronella girondica, Santos et al 2012; Macroprotodon spp., ; Malpolon spp., Carranza et al 2006; Natrix maura, Guicking et al 2008; Vipera latastei complex, Velo-Antón et al 2012), while Moroccan and Iberian populations can be often very similar (e.g., Pleurodeles waltl, Veith et al 2004;Mauremys leprosa, Fritz et al 2006b;Testudo graeca, Fritz et al 2009b;Graciá et al 2013;Macroprotodon brevis, Carranza et al 2004;Malpolon monspessulanus, Carranza et al 2006). This suggests that the Straits of Gibraltar constitutes no significant biogeographic barrier for these taxa, and this may be especially true for E. orbicularis, as indicated by the weak differentiation of pond turtles from southern Spain (Doñana National Park) and Morocco (Fig.…”

Diversity and conservation of Algerian amphibian assemblages

“…Other workers (ARANO et al, 1998;CARRANZA & WADE, 2004;FROMHAGE et al, 2004;MARTÍNEZ-SOLANO et al, 2004;VEITH et al, 2004) have also discovered genetic discontinuities of the same order of magnitude. BARBADILLO et al (1997), and later CARRANZA & WADE (2004) and PAULO et al (2008), presented very convincing hypotheses based on fragmentation of basal populations, before and during the Messinian Crisis, to explain discontinuities. These authors suggested that the area now comprising the coast of northwestern Africa and the southern Iberian Peninsula once belonged to a series of islands belonging to a geologic complex named Alkapeca (MICHARD et al, 2002).…”

Challenges and pitfalls in the characterization of anonymous outlier AFLP markers in non-model species: lessons from an ocellated lizard genome scan

“…The same individual carries also an European allele at the melanocortin-1 receptor gene (JF732954, Nunes et al, 2011b). Although technical errors cannot be entirely ruled out, the cytochrome b haplotype obtained for this individual undoubtedly belongs to the North African clade (AF378959, Paulo et al, 2008), and it clusters with Moroccan samples based on neutral microsatellites (Paulo, unpublished data). Given the long time (about 11 million years) of divergence and isolation of this species from European lizards , it is unexpected to find such a level of ancestral polymorphism retained in a single individual at the nuclear level.…”

“…The species is widespread throughout the Iberian Peninsula in a variety of ecological conditions that are strongly influenced by the distribution of precipitation and temperature ranges. Morphological and genetic differentiation in populations from the northwest and southeast of the Iberian Peninsula are strong enough to consider those populations as distinct subspecies: Lepida lepida iberica and Lepida lepida nevadensis, respectively (Mateo and Castroviejo, 1990;Paulo et al, 2008). The first lives in a rainy and lesswarm weather regime, whereas the second inhabits a region that experiences hot summers and the lowest annual rainfall across the species' distribution range.…”