CONNECTION BETWEEN SEXUAL DIMORPHISM IN S IZE AND SOCIAL-SYSTEMS IN WADERS (CHARADRIIFORMES, AVES), BREEDING IN NORTHEAST YAKUTIA

Sexual dimorphism in body mass was studied in 15 species of waders, br eeding in North-East Yakutia. Allometric equations for female body mas s as a function of male body mass were calculated in different groups, depending on the social system. Correlation was found between sexual dimorphism in size and the mating system, and between sexual size dimo rphism and parental care. The smaller mate has the greatest investment into offspring. If both sexes have display similar parental care, the ir size is nearly equal. All monogamous species do not display signifi cant sexual dimorphism in size. In polygamous species the dimorphism i s more pronounced: the male is larger in those with polygyny, whereas polyandry is characterised by a reverse condition.