TESTING MULTIVARIATE PATTERNS OF WITHIN-ISLAND DIFFERENTIATION IN PODARCIS-DUGESII FROM MADEIRA

Podarcis dugesii is a polymorphic species found on the ecologically-he terogeneous Atlantic island of Madeira. Patterns of geographic variati on in size-free body dimensions (body shape), scalation, and size were portrayed on maps with isophene contours. There was no dominant patte rn of among-site variation as seen in several other island lizards, al though some linear combinations of morphological variables showed evid ence of dines towards the east coast. Multivariate statistical techniq ues were developed to evaluate whether morphological variation contain ed an ecology-related spatial pattern, after removal of the effects of statistical non-independence of studied populations. Specifically, a partial correlation matrix comparison method provided evidence to supp ort a proposed elevation model of among-site divergence in scalation a nd body size, with both an alternative rainfall model and spatial non- independence held constant. Similar divergence in scalation has been o bserved in other lizard species on other island archipelagos as well o n some continental areas. The rainfall model was rejected for both bod y shape and scalation. The degree of within-population polymorphism in body shape and scalation showed no clear geographic trends in general , although the elevation and rainfall models could not be rejected for female scalation.