Study on Zoomorphic Variation with Copulation Duration in Centrobolus

Abstract

Centrobolus typically has prolonged copulation as a form of syn-copula mate-guarding. Variations in the copulation duration were calculated and analyzed in four species of the millipede genus Centrobolus. Mean copulation durations differed between all four species but only two species were different intra-specifically. C. inscriptus was different from C. anulatus in copulation duration coefficient of variation (CV) (F=0.41490, d.f.=114, 7, p=0.04892) and C. fulgidus and C. anulatus were different in copulation duration CV (F=0.38912, d.f.=50, 7, p=0.04836). Copulation duration was variable intra-specifically but tends to be intermediate and determining evolutionarily (interspecifically). Copulation duration was significantly correlated (Spearman’s Rho Calculator) with male and female volumes (r=1, p=0, n=4, 4; 4, 4). When I controlled for sex, I found copulation duration was significantly correlated with size (volumes) (r=0.6655, r²=0.4429, p=0.004897, n=8, 8). Larger male and female body sizes correlate with copulation duration both intra-specifically and inter- specifically in millipedes, and perhaps in animals.