PHYSIOLOGICAL VARIATION IN THE DOG-WHELK NUCELLA-LAPILLUS, L EITHER SIDE OF A CLINE IN ALLOZYME AND KARYOTYPE FREQUENCIES

Genetic constitution in the intertidal gastropod Nucella lapillus infl uences variation in shell shape and growth rate which in turn are corr elated with such habitat variables as wave action and temperature. We have investigated the response to hyperosmotic stress of samples from a dine in karyotype and allozyme frequencies and shell shape. Animals with a shell shape associated with environments where temperature and desiccation stress are important respond less to hyperosmotic stress t han animals living in a high wave energy environment. With regard to t he interaction between shell shape, physiology and habitat, animals wi th elongate shells associated with protected shores are shown to exhib it a reduced response to hyperosmotic stress compared to animals with a more spherical shell shape; this is discussed in relation to the pro duction of an adaptive phenotype.