Shell shape variation and fitness variables in the gastropod Littorina saxatilis

On shores on the east coast of Yorkshire, England, the gastropod Littorina saxatilis shows consistency in shell shape variation in samples taken from the upper portion of its intertidal range. Using analysis of shell dimensions by standard multivariate techniques and extended eigenshape analysis, this variation can be dissected into different aspects, and related to the ‘Raup growth parameters’. Some of the shell variation is shown to be related to the relative proportions of body and brood mass, and to an estimate of reproductive effort. This implies an association (perhaps indirect) between subtle variations in shell shape and fitness variables.