Less fit Lamium amplexicaule plants produce more dispersible seeds

Theory predicts that less fit individuals would disperse more often than fitter ones (Fitness Associated Dispersal, FAD hypothesis). To test this prediction under laboratory conditions, an entire life cycle of Lamium amplexicaule plants and the preferences of its dispersal agent, Messor ebeninus ants, were tracked. Characterization of individual L. amplexicaule plant revealed high variability in spot cover on the surface of the seeds, where less fit plants produce “unspotted seeds” (see Fig. 1 in Introduction). Unspotted L. amplexicaule seeds showed higher variation in germination time and lower germination rate. Moreover, M. ebeninus ants preferably collected these unspotted seeds. Our results show that low fitness L. amplexicaule plants produce seeds with higher potential for dispersal, supporting the FAD hypothesis in a plant-animal system.