Local scales condition stronger than geographical scales in the morphometric variations of rocky shore gastropods.

BIGATTI G; SEBASTIAN GIULIANELLI; NIETO VILELA RA; FEDERICO MARQUEZ

Workshop; II Workshop latinoamericano de otolitos y otras estructuras calcificadas; 2019

Since the description of ecogeographical rules, morphological variation has usually been analyzed latitudinally, ignoring the variation at micro-geographic scales. The goal of this work is to study shell form variation in Trophon geversianus at a microscale (intertidal vs subtidal) and macroscale (latitudinal) to determine which scale is more influential in marine gastropod shell form variation. We collected alive adults of T. geversianus from three localities along a latitudinal range (400 km) from both intertidal and subtidal rocky shores (0.3 km). We analyzed shell morphology using classic and 3D geometric morphometrics. Significant differences in form and shape were found within the microscale. In the macroscale different locality grouping were registered separating the habitats that the gastropods inhabit. Finally, when comparing all the sampled sites together, we found that the principal shell shape separation was also at the microscale. Accordingly, we propose that the use of empty shells must be avoided in morphometric studies regarding latitudinal variations, as origin of the samples is unknown and could lead to an erroneous interpretation of the results. Collectively, our results are a milestone with important implications for future ecological, biogeographic and paleo-ecological studies as well as the revision of theories carried out previously.