Shell variation in Patellid limpets: scales of spatial variability

World Congress of Malacology, Universidade dos Açores, Ponta Delgada, 21-28 de julho.

Species o f the genera Patella generally display a high degree of shell variation, which is thought to be an adaptation to environmental conditions. The present work examines the variation in the morphometry of the two patellid limpets present in the Azores (Patella candei and P. aspera) at multiple spatial scales. Individuals of both patellid species were collected on two sites in each of the nine islands of the Azores. All individuals were measured to estimate base ellipticity, base eccentricity, conicity and cone eccentricity. Shell variation in P. candei was consistent among groups of islands (eastern, central, western) but there was significant variation in shell morphometry at the scales of islands and sites. Components of variation showed that a substantial proportion of variation was associated with the scale of individuais. Shell variation in P. aspera was consistent at the scale of island groups and islands but there was significant variation among sites. Analysis of the components of variability showed that variability in shell morphometrv was mostly associated with differences among individuais. Overall, these results suggest that variation in shell morphometry in the two patellid is not influenced by large scale processes as would be expected given that P. candei and P. aspera both have a pelagic Iarvae. In addition, this study suggests that shell variation in these species is likely to be a result of an adaptation to local conditions (e.g. microhabitats).