Our new paper on fern mating systems has just been published in early view by New Phytologist! This study looks at mating systems in 115 species of ferns, and we found that capacity for gametophytic selfing, an extreme form of inbreeding only possible in homosporous plant lineages, is widespread in ferns, with up to 70% of species capable of undergoing gametophytic selfing in the lab.

Sessa EB, WL Testo, and JE Watkins, Jr. (2016) On the widespread capacity for, and functional significance of, extreme inbreeding in ferns. New Phytologist.


  • Homosporous vascular plants utilize three different mating systems, one of which, gameto- phytic selfing, is an extreme form of inbreeding only possible in homosporous groups. This mating system results in complete homozygosity in all progeny and has important evolution- ary and ecological implications. Ferns are the largest group of homosporous land plants, and the significance of extreme inbreeding for fern evolution has been a subject of debate for decades.
  • We cultured gametophytes in the laboratory and quantified the relative frequencies of sporophyte production from isolated and paired gametophytes, and examined associations between breeding systems and several ecological and evolutionary traits.
  • The majority of fern species studied show a capacity for gametophytic selfing, producing sporophytes from both isolated and paired gametophytes. While we did not follow sporo- phytes to maturity to investigate potential detrimental effects of homozygosity at later devel- opmental stages, our results suggest that gametophytic selfing may have greater significance for fern evolution and diversification than has previously been realized.
  • We present evidence from the largest study of mating behavior in ferns to date that the capacity for extreme inbreeding is prevalent in this lineage, and we discuss its implications and relevance and make recommendations for future studies of fern mating systems.