| Abstract |
Sex ratio skewed towards adult females has been detected in the majority of Thalassinidea species.Among the hypotheses proposed to explain this pattern, differential mortality of adult males due to intraspecific agonistic interaction is the most applyable to Callicirus major.Limb damage, which is known to potentially increase mortality in crustaceans, was studied in adult males of a C.major population on Bareque‡aba Beach, SÆo SebastiÆo, SÆo Paulo (45o26'W/23o49'S), a sheltered sandy beach in southeastern Brazil.Temporal variation (April 1994 to December 1995) of percentage of individuals bearing non-typical (regenerating) larger chela (%RC) and relative size of the larger chela (RSC= propodus length/dorsal oval length) were analysed in conjunction to other biological parameters of the population: percentage of individuals with well calcified larger chela in males (%WCCM) and females (%WCCF); index of ovary development (IOD=ovary width/dorsal oval lenght); percentage of ovigerous females.Peaks of %RC and low mean RSC occured during transition from molting to intermolt periods of males (late summer/early fall).Mean RSC of molting (1.02, N=66) and intermolt (1.13, N=112) periods differed significantly (U= 2752, p<0.01).RSC was correlated to IOD (rs=0.65, p=0.02, N=13) and to %WCCF (rs=-071, p=0.01, N=13) while %RC was correlated to %WCCF (rs=0.65, p=0.02, N=13).Since molting in female C.major is related to reproduction, the present results strongly suggest that injuries that might cause mortality occur in males involved in reproductive activity |
Shimizu, R.M. and S. de A. Rodrigues (1999) Is sex ratio in Callichirus major (Say, 1818) (Decapoda: Thalassinidea) determined by agonistic interaction of males? Program and Abstracts of the 1999 The Crustacean Society Summer Meeting. 