Copulation duration variation in worm-like millipedes

Copulation duration is a response to sperm competition. Of many determining factors of copulation duration across arthropods, I investigated variation in copulation duration in mate-guarding in worm-like millipedes. The null hypothesis was mean copulations and standard deviation in copulation duration were independent. Copulation durations and standard deviations for 11 populations of millipedes were obtained from the literature. Copulation durations were strongly correlated with standard deviations in southern African populations (r=0.8824, r2=0.8824, n=11, p=0.000323). These ranged from Calostreptus sp. (Sengwa) (33.8±22.9 min.) to Doratogonus (=Alloporus) uncinatus (Hwange) (205.8±60.8 min.) and included three forest species. Female size was correlated to standard deviation in copulation duration in savanna millipedes (r=0.9269, r2=0.8591, n=8, p=0.000924). Male size was correlated to standard deviation in copulation duration in savanna millipedes (r=0.9337, r2=0.8718, n=8, p=0.000693). There was no significant difference between the correlation coefficients of male against female variation (z=0.07997498, n=8, 8, p=0.93625715).