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Aim: Recent biogeographical studies have postulated a North African, Late Pleistocene, origin for some species of the Iberian Peninsula. However, a robust assessment of such range expansions requires high-resolution molecular tools to resolve overlapping biogeographical and cultural processes. Here we aim to determine whether the spur-thighed tortoise, Testudo graeca, arrived in south-eastern Spain during historical or prehistoric times, and whether its dispersal to the Iberian Peninsula was human-mediated. Location: The western Mediterranean Basin (south-eastern Spain, northern Algeria and north-western Morocco). Methods: Using 428 samples from 19 sites in North Africa and 18 in south-eastern Spain, we obtained mitochondrial sequences from the cytochrome b gene and genotypes derived from seven microsatellite loci. These data were employed to obtain population genetics descriptors, haplotype networks, Bayesian cluster analyses and isolation-by-distance patterns. Moreover, we used a Bayesian demographic approach to delimit the dates involved in the range expansion. Results: We found lower levels of genetic variability and weak mitochondrial differentiation in the south-eastern Spanish tortoises compared with the North African ones. However, exclusive haplotypes occurred in the Iberian samples and microsatellite cluster analyses revealed moderate levels of admixture across both sides of the Mediterranean. A coastal area in the west of Algeria and the central-southern region in south-eastern Spain are suggested as the most probable founder and arrival places, respectively. Finally, we identified signatures of an ancient bottleneck event approximately 20,000-30,000 years ago. Main conclusions: The spur-thighed tortoise probably arrived in south-eastern Spain during Late Pleistocene sea-level low stands. The role that humans may have played as dispersers across the Mediterranean remains unclear. Our results are in accordance with other recent findings of trans-Mediterranean expansions during this period and highlight the importance of employing precise methodological approaches before a species can be considered as historically introduced. © 2012 Blackwell Publishing Ltd.

Research was supported by grants from Fundacao para a Ciencia e Tecnologia (FCT): SFRH/BD/25012/2005 (to R.V.), PTDC/BIA-BDE/74288/2006 (to D.J.H.); from the Ministerio de Educacion y Ciencia, Spain: CGL2009-11663/BOS, Grup de Recerca Emergent of the Generalitat de Catalunya: 2009SGR1462, and an Intramural Grant from the Consejo Superior de Investigaciones Cientificas, Spain: 2008301031 (to S.C.).

Aim To determine genetic substructuring within the lacertid lizard Psammodromus algirus. To compare levels of variation across a geological barrier, the Strait of Gibraltar, and to compare this against the known age of the barrier using a molecular clock hypothesis. To compare the effect of the barrier within this species with previously published data from other organisms. Location The Iberian Peninsula and North Africa. Methods Partial sequences from the mitochondrial cytochrome b, 12S rRNA and 16S rRNA genes were obtained from 101 specimens belonging to the subfamily Gallotiinae and used in this study. The data set was aligned using ClustalX and phylogenetic trees produced using both maximum-parsimony and maximum-likelihood methods. Maximum likelihood estimates of divergence times for the combined data set (12S + 16S + cytochrome b) were obtained after discovery of lineage rate constancy across the tree using a likelihood ratio test. Results Psammodromus algirus contains divergent eastern and western mtDNA clades within the Iberian Peninsula. The western clade has northern and southern lineages in Iberia and one in North Africa. This phylogeographical pattern indicates that the lizard invaded North Africa after the opening of the Strait, presumably by natural rafting. Main conclusions As in several other species, current patterns of genetic diversity within P. algirus are not directly related to the opening of the Strait of Gibraltar. Widespread sampling on both sides of the barrier is necessary to determine its effect on species in this area accurately.

Aim Cryptoblepharus is a genus of small arboreal or rock-dwelling scincid lizards, widespread through the Indo-Pacific and Australian regions, with a disjunct outlier in the Malagasy region. The taxonomy within this genus is controversial, with different authors ranking the different forms (now some 36) at various levels, from different species to subspecies of a single species, Cryptoblepharus boutonii. We investigated the biogeography and genetic differentiation of the Cryptoblepharus from the Western Indian Ocean region, in order to understand their origin and history. Location Western Indian Ocean region. Methods We analysed sequences of mitochondrial DNA (partial 12s and 16s rRNA genes, 766 bp) from 48 specimens collected in Madagascar, Mauritius, the four Comoros islands and East Africa, and also in New Caledonia, representing the Australo-Pacific unit of the distribution. Results Pairwise sequence divergences of c. 3.1% were found between the New Caledonian forms and the ones from the Western Indian Ocean. Two clades were identified in Madagascar, probably corresponding to the recognized forms cognatus and voeltzkowi, and two clades were identified in the Comoro islands, where each island population formed a distinct haplotype clade. The East African samples form a monophyletic unit, with some variation existing between Pemba, Zanzibar and continental Tanzania populations. Individuals from Mauritius form a divergent group, more related to populations from Moheli and Grand Comore (Comoros islands) than to the others. Main conclusions The level of divergence between the populations from the Western Indian Ocean and Australian regions and the geographic coherence of the variation within the Western Indian Ocean group are concordant with the hypothesis of a colonization of this region by a natural transoceanic dispersal (from Australia or Indonesia). The group then may have diversified in Madagascar, from where it separately colonized the East African coast, the Comoros islands (twice), and Mauritius. The genetic divergence found is congruent with the known morphological variation, but its degree is much lower than typically seen between distinct species of reptiles.

Aim To examine the effect of a known geological barrier on genetic variation within a wall lizard species complex. Location The Iberian Peninsula and North Africa. Methods Sequencing of partial 12S rRNA and cytochrome b mtDNA. Results The current distribution of genetic variability is not related to the opening of the Strait of Gibraltar. Conclusions Podarcis hispanica in North Africa is probably a species complex. The Strait of Gibraltar should not be used as a known barrier to gene flow in other land based organisms without careful sampling to test for multiple crossings since its formation.