The evolutionary dynamics of plant mating systems: how bias for studying ‘interesting’ plant reproductive systems could backfire

Abstract Background and Aims An “abominable mystery”: angiosperm sexual
systems have been a source of both interest and frustration for the
botanical community since Darwin. The evolutionary stability, overall
frequency, and distribution of self-fertilization and mixed-mating systems
have been explored in a variety of studies. However, there has been no
recent study which directly addresses our knowledge of mating systems
across families, the adequacy of existing data, or the potential for
biases. Scope Here we present an updated dataset of mating systems across
flowering plants covering 6,781 species and 212 families based on a
synthesis of existing reviews and an original literature review using Web
of Science. We assess the adequacy of this data by evaluating for bias
indicating enrichment of certain families or sexual systems.  Key
Results We find that the vast majority of our data on mating systems comes
from a small number of disproportionally sampled families, and that
families with significant proportions of dioecious or monoecious species
are much more likely to be undersampled. Conclusions Our results show that
the frequency of selfing in angiosperms is overestimated, possibly due to
increased research interest in selfing and mixed-mating systems. This
suggests that systematic study bias may mean we know less about this vital
facet of plant life than we think.