Evolution and maintenance of colour pattern polymorphism in Liopholis (Squamata:Scincidae)

Abstract

We examined the evolution and maintenance of colour pattern polymorphism in an Australian lineage of scincid lizards, the genus Liopholis. Liopholis comprises 11 species, with representatives in both the temperate zone and arid zone. Specimens from all major Australian museums were examined to characterise colour pattern polymorphism within Liopholis, and investigate geographic variation in the relative abundance of morphs within polymorphic species. We used a previously published phylogeny for Liopholis to investigate the evolution and maintenance of colour pattern polymorphism within the group. Five species were found to exhibit colour pattern polymorphism (L. margaretae margaretae Storr, L. m. personata Storr, L. montana Donnellan et al., L. multiscutata Mitchell & Behrndt, L. pulchra Werner, L. whitii Lacépède), with six species being monomorphic (L. guthega Donnellan et al., L. inornata Rosén, L. kintorei Stirling & Zietz, L. modesta Storr, L. slateri Storr, L. striata Sternfeld). Three colour morphs occur in L. whitii, with the relative abundance of each varying significantly among latitudes. The patterned morph is most common, while the incidence of the plain-back morph decreases at latitudes higher than 35°S. The L. whitii patternless morph occurs only within a narrow latitudinal band (34-38°S). In L. multiscutata, the relative abundance of the patterned (∼89-93%) and patternless morph (∼7-11%) is consistent across regions, except for the Nullarbor Plain region where the patternless morph is more common (∼39%). Our analyses suggest a single origin of colour pattern polymorphism in Liopholis, followed by the subsequent loss of polymorphism on four occasions. The secondary loss of polymorphism might be associated with climate or habitat, possibly as the result of shifts into the arid zone or alpine regions of Australia. This study provides the necessary framework for future studies of colour pattern polymorphism in Liopholis.