Dugès, A. (1829) - Mémoire sur les espèces indigènes du genre Lacerta. - Annales des Sciences naturelles, 16, 337–339.  Fitze, P.S. & Gonzalez-Jimena, V. & San-Jose, L.M. & San Mauro, D. & Aragón, P. & Suarez, T. & Zardoya, R. (2011) - Integrative analyses of speciation and divergence in Psammodromus hispanicus (Squamata: Lacertidae) - BMC Evolutionary Biology, 11: 347. 21 pp.   × Background
Genetic, phenotypic and ecological divergence within a lineage is the result of past and ongoing evolutionary processes, which lead ultimately to diversification and speciation. Integrative analyses allow linking diversification to geological, climatic, and ecological events, and thus disentangling the relative importance of different evolutionary drivers in generating and maintaining current species richness.
Results
Here, we use phylogenetic, phenotypic, geographic, and environmental data to investigate diversification in the Spanish sand racer (Psammodromus hispanicus). Phylogenetic, molecular clock dating, and phenotypic analyses show that P. hispanicus consists of three lineages. One lineage from Western Spain diverged 8.3 (2.9-14.7) Mya from the ancestor of Psammodromus hispanicus edwardsianus and P. hispanicus hispanicus Central lineage. The latter diverged 4.8 (1.5-8.7) Mya. Molecular clock dating, together with population genetic analyses, indicate that the three lineages experienced northward range expansions from southern Iberian refugia during Pleistocene glacial periods. Ecological niche modelling shows that suitable habitat of the Western lineage and P. h. edwardsianus overlap over vast areas, but that a barrier may hinder dispersal and genetic mixing of populations of both lineages. P. h. hispanicus Central lineage inhabits an ecological niche that overlaps marginally with the other two lineages.
Conclusions
Our results provide evidence for divergence in allopatry and niche conservatism between the Western lineage and the ancestor of P. h. edwardsianus and P. h. hispanicus Central lineage, whereas they suggest that niche divergence is involved in the origin of the latter two lineages. Both processes were temporally separated and may be responsible for the here documented genetic and phenotypic diversity of P. hispanicus. The temporal pattern is in line with those proposed for other animal lineages. It suggests that geographic isolation and vicariance played an important role in the early diversification of the group, and that lineage diversification was further amplified through ecological divergence.
Fitze, P.S. & Gonzalez-Jimena, V. & San-Jose, L.M. & San Mauro, D. & Zardoya, R. (2012) - A new species of sand racer, Psammodromus (Squamata: Lacertidae), from the Western Iberian Peninsula - Zootaxa 3205: 41–52 (2012) × A new species of lacertid lizard of the genus Psammodromus is described from the Iberian Peninsula. Genetic and recently
published phenotypic data support the differentiation of Psammodromus hispanicus into three, and not as previously suggested two, distinct lineages. Age estimates, lineage allopatry, the lack of mitochondrial and nuclear haplotype sharing between lineages, ecological niche divergence, and the current biogeographic distribution, indicated that the three lineages correspond to three independent species. Here, we describe a new species, Psammodromus occidentalis sp. n., which is genetically different from the other sand racers and differentiated by the number of femoral pores, number of throat scales, snout shape, head ratio, green nuptial coloration, and number of supralabial scales below the subocular scale. We also propose to upgrade the two previously recognized subspecies, Psammodromus hispanicus hispanicus Fitzinger, 1826 from central Spain and Psammodromus hispanicus edwardsianus (Dugès, 1829) from eastern Spain, to the species level: Psammodromus hispanicus stat. nov. and Psammodromus edwardsianus stat. nov. Given that the holotype of Psammodromus hispanicus was lost, we designate a neotype. We also analysed museum specimens of P. blanci, P. microdactylus and P. algirus to describe differentiation of the Psammodromus hispanicus lineages/species from their closest relatives. Mendes, J. & Harris, D.J. & Carranza, S. & Salvi, D. (2017) - Biogeographical crossroad across the Pillars of Hercules: Evolutionary history of Psammodromus lizards in space and time. - Journal of Biogeography, 44 (12): 2877-2890. × Aim
To infer the biogeographical and evolutionary history of the Western Mediterranean Psammodromus lizards with the aim of assessing the role of vicariance and dispersal on the cladogenetic events within the palaeogeological dynamics of the Strait of Gibraltar.
Location
North Africa and Western Europe.
Methods
We built a dataset including all six species of Psammodromus using mitochondrial (12S, cytb, nd4) and nuclear (acm4, mc1r, pomc) gene fragments. Species tree and concatenation methods were used to infer phylogenetic relationships and divergence times. Phylogenies were used for biogeographical inference using S-DIVA, DEC and BBM.
Results
Psammodromus probably originated in Iberia, with P. algirus diverging early. The ancestor of the African P. blanci and P. microdactylus dispersed to Africa through the Betic-Rif massif, c. 10 Ma. The cladogenetic events within Africa and Iberia were probably due to vicariance mediated by habitat and climatic changes at the end of the Miocene (P. blanci and P. microdactylus) and during the Pliocene (P. occidentalis, P. hispanicus and P. edwardsianus). Psammodromus algirus shows three lineages, two in Iberia and one in Africa, the latter originated following a transmarine dispersal during the Middle Pleistocene (1.5 Ma).
Main conclusions
Over-sea dispersal has played a major role in intercontinental exchange and divergence in Psammodromus, with two dispersal events towards Africa that occurred 10 and 1.5 Ma resulting in the African lineages. This study, combined with previous literature, provides compelling evidence that major biotic exchanges took place across the Strait of Gibraltar well before or long after the land connection during the Messinian Salinity Crisis (MSC, 5.9–5.33 Ma). These findings suggest caution in the application of the relatively short event of Atlantic flooding at the end of the MSC as cause for divergence in molecular clock calibrations, which is a popular approach in literature.
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