Macrostomum biology

For sexually reproducing animals, the absence of a mate usually spells disaster. This is not necessarily so for simultaneous hermaphrodites (who have both male and female sex organs at the same time), because they have a potential “escape route” available if only they could somehow contrive to have their own sperm fertilise their own eggs. It’s an imperfect solution, as any offspring produced by “selfing” in this way will be inbred and probably of lower fitness, but it’s better than leaving no offspring at all. In a new study with Lukas Schärer and Dita Vizoso from the University of Basel, Switzerland, I show that the flatworm Macrostomum hystrix is indeed capable of switching to just such selfing behaviour in the prolonged absence of a mating partner. What’s more, we demonstrate that some worms are more likely to self than others, and that their offspring inherit this selfing propensity. The paper is published today online in the Journal of Evolutionary Biology.

Ramm SA, Vizoso DB & Schärer L. Occurrence, costs and 
heritability of delayed selfing in a free-living flatworm. 
Journal of Evolutionary Biology, doi:10.1111/jeb.12012