CONTRASTING PATTERNS OF HERITABLE GEOGRAPHIC VARIATION IN SHELL MORPHOLOGY AND GROWTH POTENTIAL IN THE MARINE GASTROPOD BEMBICIUM VITTATUM: EVIDENCE FROM FIELD EXPERIMENTS.

Similar phenotypes do not always imply similar genotypes. In species distributed over a broad latitudinal range, geographical variation in morphological and life-history traits may reflect very different relations between genotypic and environmental effects on these traits. Patterns of selection among latitudinally separated sites may minimize phenotypic differences in life-history traits but promote phenotypic differences in form.

Role of dispersal ability in the phenotypic differentiation and plasticity of two marine gastropods : I. Shape.

Species with contrasting abilities for dispersal may adopt different strategies in response to wide ranges of environmental conditions. These strategies were investigated here by comparisons of phenotypic differentiation and plasticity in the gastropods Austrocochlea constricta and Bembicium vittatum, which coexist in a range of intertidal habitats on the Abrolhos Islands and Albany in Western Australia. They differ in their potential for larval dispersal, A.