THE ADAPTIVE SIGNIFICANCE OF COLOR PATTERN POLYMORPHISM IN THE AUSTRALIAN SCINCID LIZARD LAMPROPHOLIS-DELICATA

Females of Lampropholis delicata are dimorphic for colour pattern, the difference between morphs being the presence or absence of a distinct white mid-lateral stripe. A less distinct striped morph occurs also i n males. We evaluated alternative hypotheses for the maintenance of th is polymorphism by examining temporal and spatial variation in morph f requency, testing for differential selection among morphs using data o n body size and reproductive traits from preserved specimens, and expe rimentally manipulating colour pattern in free-ranging lizards of both sexes, to assess the influence of the lateral stripe on survival rate s. We found that the relative frequency of striped individuals varied among populations and decreased from north to south in both sexes, coi ncident with an increasing incidence of regenerated tails. Morph frequ encies did not change through time within a population. Striped gravid females appeared to survive better and produced larger clutches than did non-striped females. In our experimental study, the relationship b etween survival and colour morph differed between the two sexes; males painted with a white lateral stripe had lower survival than control ( brown stripe) males, but survival did not differ between striped and c ontrol females. The different response in the two sexes may be due par tly to differences in temperature and microhabitat selection. We propo se that the white lateral stripe decreases susceptibility to predators in gravid females but increases risk of predation in males, especiall y in combination with low temperatures. The polymorphism might be main tained by: (1) opposing fitness consequences of the stripe in males an d females; (2) sex-specific habitat selection; and (3) gene flow in co mbination with spatial variation in relative fitness of the two morphs . (C) 1995 The Linnean Society of London.