Meeting Abstract

P2-58   -   Physiological condition, and not competitive ability, is the key difference between mating and non-mating male fiddler crabs Leptuca pugilator in a Florida population Lane, ZM*; Darnell, MZ; University of Southern Mississippi, School of Ocean Science and Engineering, Ocean Springs, MS; University of Southern Mississippi, School of Ocean Science and Engineering, Ocean Springs, MS zachary.lane@usm.edu

The Atlantic sand fiddler crab, Leptuca pugilator, is endemic to the intertidal zones of sandy beaches and marshes along the Gulf and Atlantic coasts of the U.S.A from Panacea, FL to Cape Cod, MA. Within a population, males are spatially segregated in two areas: the high intertidal mating area and the low intertidal foraging area. Males in the high-intertidal mating area maintain and defend burrow-centered territories and pursue mating opportunities at the cost of thermal stress, starvation, and energetically-taxing intraspecific interactions, while foraging males in the low intertidal are subjected to much lower stress levels overall but are unable to mate. In this study, we aimed to determine what morphological, physiological, and behavioral factors differentiate the males found in the mating and foraging subpopulations. In particular, we considered differences in size, competitive ability, territoriality, and physiological condition (measured as claw closing force) of males in each area. Both high-intertidal territory-holding (resident) males and low-intertidal foraging males performed identically in combat, with no difference in the probability of combat initiation, level of combat escalation, fight outcomes, and fight durations. Likewise, body size, claw size, and territory holding ability did not differ between the two groups. Claw closing force was greater in high-intertidal resident males than low-intertidal foraging males. These results suggest that males forage in the low intertidal until they are strong enough to successfully mate. Then, after acquiring a territory in the high intertidal zone, males remain until cumulative effects of heat stress and low food availability decrease physiological condition below some threshold at which time they return to the low intertidal to feed and recover.