Molecular evidence of polyandry and polygyny in the mating system of the non-biting midge Chironomus riparius (Diptera: Chironomidae)

Chironomus riparius (Insecta: Diptera) is an ecological and environmental flagship species widely distributed in organically enriched waters throughout the temperate latitudes of the Northern Hemisphere. The present study elucidates the mating system of C. riparius using molecular evidence of the reproductive strategies employed by both sexes. A total of 760 larvae from 19 egg masses collected from two different wild populations (Sarayk?y and Pamukkale) in Denizli, T?rkiye, were genotyped at the MSC1 and MSC4 microsatellite loci, and the number of fathers per egg mass was inferred using GERUD and COLONY. Multiple paternity was detected in all sampled egg masses from both populations, with notable differences in the mean number of fathers between them. C. riparius exhibited skewed paternity in populations with male-biased breeding sex ratios. The species is polygynandrous, with both sexes mating with multiple partners. The high frequencies of multiple paternity observed in this study likely indicate substantial genetic diversity within these populations, supporting the species? persistence across diverse ecological conditions.