Male size-dependent dominance for burrow holding in the semiterrestrial crab Neohelice granulata: multiple tactics used by intermediate-sized males

SAL MOYANO MP; LORUSSO M; NUÑEZ J; RIBEIRO P; GAVIO MA; LUPPI T

BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY

SPRINGER

Lugar: Berlin; Año: 2016 vol. 70 p. 1497 - 1505

0340-5443

Dominance and the establishment of social hierarchiesare frequently related to size: the larger individuals gaingreater reproductive success, while the smaller ones displayalternative mating strategies.We studied the existence of dominanceand the alternative mating strategies among Neohelicegranulata small (SM) and large (LM) males competing forburrows. LM construct burrows with copulation chamberswhile SM do not. Field studies showed the existence of aSM?s size-range of 30?32 mm carapace width when theychange behavior and occupy burrows with copulation chambers(hereafter referred to as the Bswitch size-range^). Wefound a restricted size-range in mating pair formation.Laboratory experiments showed that LM dominate SM becauseSM did not construct burrows in the presence of LM,and LM displaced SM from their burrows. When given thechance, recently mated SM occupied burrows without copulationchambers while not recently mated SMoccupied chamberedburrows. This is evidence that these males may bedisplaying a cheating mating strategy to copulate with femaleslooking for these burrows: they occupy but do not own theseburrows. SM can also intercept and mate females on the surface.Given the size restriction in pair formation, intermediatesizedmales in the switch size-range (30?32 mm carapacewidth) may copulate with a broader female size-range, largerand smaller than themselves. In this way, SM in the switch size-range may be acquiring a higher reproductive success byadopting multiple tactics. Male dominance hierarchies havebeen well documented in crustaceans, except for crabs.Here, we demonstrate male dominance related to the constructionand defense of burrows and male size in the crabN. granulata. We found that small males of a certain sizerange adopt an alternative Bcheating^ mating strategy thatcan enhance fitness. Therefore, although they are not largeand dominant, small males can nevertheless achieve high reproductivesuccess as a result of this alternative reproductivetactic.