title: Stress promotes maleness in hermaphroditic modular animals.
abstract: Sex-allocation theory developed for hermaphroditic plants predicts that impaired phenotype or reduced parental survivorship caused by environmental stress should induce relatively greater allocation to the male function. We provide experimental evidence of stress-induced maleness, already well documented in flowering plants, in a modular animal. By using cloned copies of replicate genotypes, we show that the marine bryozoan Celleporella hyalina increases the ratio of male to female modules in response to diverse environmental stressors. Mating trials confirmed that paternity is determined by fair-raffle sperm competition, which should obviate local mate competition at characteristic population density and promote the advantage of increased male allocation. The demonstrated similarity to plants transcends specific physiological pathways and suggests that stress-induced bias toward male function is a general response of hermaphroditic modular organisms to impaired prospects for parental productivity or survival.
authors.affiliation: School of Biological Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, United Kingdom. r.n.hughes@bangor.ac.uk
authors.forename: R N
authors.initials: RN
authors.lastname: Hughes
authors.forename: P H
authors.initials: PH
authors.lastname: Manríquez
authors.forename: J D D
authors.initials: JD
authors.lastname: Bishop
authors.forename: M T
authors.initials: MT
authors.lastname: Burrows
mesh_terms: D000818:Animals; D002013:Bryozoa / Q000502:physiology*; D003163:Competitive Behavior; D012734:Disorders of Sex Development / Q000503:physiopathology*; D005260:Female; D008297:Male; D012744:Sex Ratio; D012726:Sexual Behavior, Animal; D013312:Stress, Physiological / Q000503:physiopathology*