Diversification of Sexual Size Dimorphism in Cyclops vicinus

The aim of this study was to qualify the sexual size dimorphism at the both inter and intra-population levels of a copepod species, Cyclops vicinus, populations living in a small-scale geographical range. Sexual size dimorphism is evaluated by the ratio of female to male total length. But, to deep insight into sexual size dimorphism we assumed that the more difference between same measurements on the body from different sexes lead to more sexual dimorphism rate. The samples were taken from four water sources locating east and southeast part of Turkey. The significant inter and intra population differences were detected. The thorax width related measurements (mostly) and abdomen length had the most effective ones with changing order in the different populations on the sexual size dimorphism. Pearson correlation coefficients (r) showed that there were strong positive relationships between sexual dimorphism rate and predator presence (r = 0.88) and water volume of lake (r=0.72), while a moderate negative relationship both with water depth (r=0.50) and with lake area (r=-0.45).