An integrated assessment of a group with complex systematics: the Iberomaghrebian lizard genus Podarcis (Squamata, Lacertidae)

A critical review of the evolutionary biology of Iberian and North African lizard members of the genus Podarcis (Lacertidae) based on phylogeny, phylogeography, morphometrics, behavior, ecology and physiology is presented. The Iberomaghrebian region is inhabited by at least 12 different evolutionary lineages that group into a monophyletic clade (except Podarcis muralis). In contrast to the current taxonomy, the saxicolous 'Podarcis hispanica' is paraphyletic with respect to Podarcis bocagei and Podarcis carbonelli, two currently recognized species. Nodes in the phylogenetic tree are deep, resulting from old divergences, clearly preceding the Pleistocene. Nevertheless, more recent range changes as a result of glaciations are also evident. The most plausible evolutionary scenario for this group indicates both vicariant and dispersal events. Although parapatry between lineages is the rule, sympatry and even syntopy are frequent, but usually between ground-dwelling and saxicolous forms. Contacts between forms with similar habitat use are rare and local. Morphological distinctiveness between lineages has been demonstrated, indicating historical constraints. However, other characters have repeatedly evolved under similar environmental pressures independently of the evolutionary lineage. Strong sexual dimorphism derives from sexual selection and is attained before sexual maturity, although developmental restrictions exist. Variation between populations is also important and derives from local variation in both natural (habitat, climate) and sexual (density) selective pressures. Evidence for short-term changes has already been found, particularly in insular populations. Reproductive isolation between syntopic forms and partner recognition are based on male-male competition and on visual and chemical recognition of females by conspecific males. Despite this ancient diversification, most forms maintain a degree of reproductive compatibility. Hybridisation may occur, but is limited, and there is evidence of selection against hybrids. The ecological analysis presented here does not support exploitative competition, but rather behavioral interference between forms. Ecomorph classification of lineages suggests character displacement between those with extensive range overlap. Finally, a critical assessment of the specific status of all lineages is provided and directions for further research are suggested.