Female reproductive success in females versus hermaphrodites has been well documented. However, documenting a potential advantage in fertility of male versus hermaphrodite individuals in subdioecious species is also essential for understanding the evolutionary pathway from hermaphroditism toward dioecy via gynodioecy. In a recent study published by Wang et al. in AoB PLANTS, siring success in terms of fruit set, fruit mass, number of seeds, and mean seed mass was compared by hand-pollinated crosses in the subdioecious shrub Eurya japonica.
Male individuals exhibited an advantage in male fertility in terms of both quantity and quality compared with hermaphrodites in hand-pollinated crosses in the subdioecious species Eurya japonica. This male advantage was prominent when the mother trees were female individuals rather than hermaphrodites. Given that the female reproductive success of females is higher than that of hermaphrodites and that hermaphrodites are self-incompatible in E. japonica, pollen limitation may inhibit the shift and permit the persistence of hermaphrodites in this E. japonica population. The subdioecious study population may be entering a transition stage to dioecy along the gynodioecy–dioecy pathway.
Wang, H., Matsushita, M., Tomaru, N., & Nakagawa, M. (2016). High male fertility in males of a subdioecious shrub in hand-pollinated crosses. AoB Plants, 8, plw067. http://dx.doi.org/10.1093/aobpla/plw067