Does the silver moss Bryum argenteum exhibit sex-specific patterns in vegetative growth rate, asexual fitness or prezygotic reproductive investment?

Kimberly Horsley, Lloyd R. Stark, D. Nicholas McLetchie

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Background and Aims Expected life history trade-offs associated with sex differences in reproductive investment are often undetected in seed plants, with the difficulty arising from logistical issues of conducting controlled experiments. By controlling genotype, age and resource status of individuals, a bryophyte was assessed for sex-specific and location-specific patterns of vegetative, asexual and sexual growth/reproduction across a regional scale. Methods Twelve genotypes (six male, six female) of the dioecious bryophyte Bryum argenteum were subcultured to remove environmental effects, regenerated asexually to replicate each genotype 16 times, and grown over a period of 92 d. Plants were assessed for growth rates, asexual and sexual reproductive traits, and allocation to above-and below-ground regenerative biomass. Key Results The degree of sexual versus asexual reproductive investment appears to be under genetic control, with three distinct ecotypes found in this study. Protonemal growth rate was positively correlated with asexual reproduction and sexual reproduction, whereas asexual reproduction was negatively correlated (appeared to trade-off) with vegetative growth (shoot production). No sex-specific trade-offs were detected. Female sex-expressing shoots were longer than males, but the sexes did not differ in growth traits, asexual traits, sexual induction times, or above-and below-ground biomass. Males, however, had much higher rates of inflorescence production than females, which translated into a significantly higher (24x) prezygotic investment for males relative to females. Conclusions Evidence for three distinct ecotypes is presented for a bryophyte based on regeneration traits. Prior to zygote production, the sexes of this bryophyte did not differ in vegetative growth traits but significantly differed in reproductive investment, with the latter differences potentially implicated in the strongly biased female sex ratio. The disparity between males and females for prezygotic reproductive investment is the highest known for bryophytes.

Original languageEnglish
Pages (from-to)897-907
Number of pages11
JournalAnnals of Botany
Issue number6
StatePublished - May 2011

Bibliographical note

Funding Information:
We thank Richard Castetter for field assistance in locating critical populations, Allen (‘Koop’) Gibbs for evolutionary discussions and the use of his microbalance, Crystal Erickson for providing sterile water, media, and Hoagland’s solution, and John Brinda and Sarah Eppley for insightful discussion and literature acquisitions. This research was supported by the National Science Foundation (IOB 0416407 to D.N.M., IOB 0416281 to L.R.S., and an undergraduate research award from the Experimental Program to Stimulate Competitive Research to K.H.).


  • Bryum argenteum
  • asexual reproduction
  • bryophyte
  • ecotype
  • gender specific fitness
  • inflorescence
  • protonema
  • reproductive investment
  • sex ratio
  • sexual reproduction
  • silver moss
  • trade-off

ASJC Scopus subject areas

  • Plant Science


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