GASTROPOD SHELL REPAIR IN THE INTERTIDAL OF BAHIA-LA-CHOYA (N. GULF OF CALIFORNIA)

Models of evolutionary escalation between gastropods and their shell-b reaking predators rely on the presence of a strong relation between pr edation intensity and repair frequency. Some previous work has suggest ed that both predation intensity and repair frequency have increased t hrough geologic time. Repair frequency (the percentage of shells with at least one repair scar) in four Recent gastropods from the northern Gulf of California shows both high interspecific (7.6% in Cerithium st ercusmuscarum to 87.9% in Turritella gonostoma) and interhabitat varia tion (11.9-30.7% in Theodoxus luteofasciatus and 26.8-64.9% in Cerithi dea albonodosa). Habitat-mixing, time-averaging and collecting practic es might diminish variation in shell repair in fossil populations. Nev ertheless, the high microhabitat variation observed here indicates tha t trends in shell repair through geologic time should consider the var iation in shell repair at any one lime. Reliable estimates of repair f requencies in fossil gastropods requires samples of several species an d several habitats. Measuring shell repair should be better standardiz ed, published data are now often difficult to compare. (C) 1997 Elsevi er Science B.V.