Integrative analyses of speciation and divergence in Psammodromus hispanicus (Squamata: Lacertidae)
1 Department of Ecology and Evolution (DEE), Université de Lausanne, Biophore, Lausanne, CH-1015, Switzerland
2 Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Calle José Gutierrez Abascal 2, Madrid, E-28006, Spain
3 Instituto Pirenaico de Ecología (IPE-CSIC), Avenida Regimiento de Galicia s/n, Jaca, E-22700, Spain
4 Fundación Araid, Edificio Pignatelli, Paseo Maria Agustin 36, Zaragoza, E-50004, Spain
5 Department of Zoology, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
6 Department of Cellular and Molecular Physiopathology, Centro de Investigaciones Biologicas (CSIC), Calle Ramiro de Maetzu 9, Madrid, E-28040, Spain
BMC Evolutionary Biology 2011, 11:347 doi:10.1186/1471-2148-11-347Published: 30 November 2011
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.
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.
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.