No evidence of colour-based microhabitat choice in a polymorphic marine snail

ABSTRACT Microhabitat choice has been proposed as a mechanism contributing to the maintenance of colour polymorphism in marine gastropods, based on observed associations between shell colour and microhabitat in certain species (e.g. Littorina saxatilis). To examine this hypothesis, different colour morphs of L. saxatilis were studied following a mark-recapture experimental design to assess whether this species preferentially chooses those microhabitats matching its shell colour, presumably favouring crypsis. Our results revealed no significant association between shell colour and microhabitat. Furthermore, despite movement patterns being affected by habitat heterogeneity, no clear evidence supporting an active search for crypsis was found. These results suggest that microhabitat choice does not play an important role in maintaining intrapopulation shell colour polymorphism in L. saxatilis, highlighting the relevance of alternative, more plausible processes such as differential predation.