Our latest experimental results in Macrostomum lignano flatworms demonstrate that individuals are able to produce sperm faster under conditions of higher sperm competition, presumably contributing to stronger sperm competitiveness. The findings are important because they imply that the speed of spermatogenesis is not a fixed property of a species or a genotype, but rather a malleable parameter that varies according to the prevailing environmental conditions. Whether or not other animals are capable of modulating the speed of spermatogenesis in this manner is currently unknown, but it could be that speeding up and slowing down spermatogenesis based on sperm competition cues is a taxonomically widespread – but until now largely overlooked – mechanism underlying phenotypic plasticity in sperm production.
The paper is based on experiments conducted by Athina Giannakara for her Master Thesis with me here in Bielefeld, in collaboration with Lukas Schärer in Basel, and has just been published in BMC Evolutionary Biology.
Sperm competition-induced plasticity in the speed of spermatogenesis. Giannakara A, Schärer L, Ramm SA (2016) BMC Evolutionary Biology 16: 60. doi: 10.1186/s12862-016-0629-9
Picture: Detail from Fig. 1 in Giannakara et al. (2016).