Piotr Michalak

Piotr developed a mathematical model to explore how seminal fluid proteins (Sfps) regulate female reproduction in Drosophila melanogaster. Sfps are transferred by males during mating and have long been considered a textbook example of sexual conflict, a way for males to manipulate female physiology at a cost to female survival. However, this view has been increasingly questioned in the literature, with a growing body of work suggesting that females may in fact use Sfps to guide their own reproductive investment. Our modelling work supports this shift. We show that Sfps can synchronize sperm and egg release, aligning different components of female fitness and increasing reproductive success. Furthermore, the binding of sex peptide to sperm ensures that Sfps honestly signal the amount of sperm remaining, allowing females to adjust their reproductive investment accordingly Michalak et al. Am.Nat. 2026. When we modelled remating, we found that Sfp-guided reproduction allows females to achieve high offspring production across a wider range of mating intervals, providing a buffer against uncertainty in mating opportunities and greater flexibility in mate choice. Importantly, Sfps also reduce the selective pressure on males to deviate from the female optimum, suggesting that rather than driving sexual conflict, Sfps can attenuate it Michalak et al. bioRxiv. The post-mating refractory period, during which females reject males, may therefore reflect female adjustment of behaviour rather than male manipulation.

Piotr’s PhD also had an experimental component. He tested whether wounds — a common injury in nature — could disrupt female reproduction when inflicted at different moments relative to mating. Despite a high early peak in offspring production suggesting a vulnerable period, females produced the same total number of offspring regardless of when they were wounded, indicating that female fecundity is remarkably robust to injury Michalak et al. Roy.Soc.Op.Sc. 2026