title: Maternal sex effects and inbreeding depression under varied environmental conditions in gynodioecious Fragaria vesca subsp. bracteata.
abstract: OBJECTIVE
  Gynodioecy (coexistence of females and hermaphrodites) is a sexual system that occurs in numerous flowering plant lineages. Thus, understanding the features that affect its maintenance has wide importance. Models predict that females must have a seed fitness advantage over hermaphrodites, and this may be achieved via seed quality or quantity. Females in a population of Fragaria vesca subsp. bracteata, a long-lived gynodioecious perennial, do not demonstrate a seed quantity advantage, so this study explored whether females produced better quality seed via maternal sex effects or avoidance of inbreeding depression (IBD).
  
  
  METHODS
  Families of selfed and outcrossed seed were created using hermaphrodite mothers and families of outcrossed seed were created using female mothers. The effects of these pollination treatments were assessed under benign conditions early in life and under varied conditions later in life. To test for an effect of maternal sex, fitness components and traits associated with acclimation to variable environments of progeny of outbred hermaphrodites and females were compared. To test for expression of IBD, fitness parameters between inbred and outbred progeny of hermaphrodites were compared.
  
  
  RESULTS
  Offspring of females were more likely to germinate in benign conditions and survive in harsh resource environments than outbred progeny of hermaphrodites. IBD was low across most life stages, and both the effect of maternal sex on progeny quality and the expression of IBD depended on both maternal family and resource condition of the progeny.
  
  
  CONCLUSIONS
  The effect of maternal sex and IBD on progeny quality depended on resource conditions, maternal lineage and progeny life stage. In conjunction with known lack of differences in seed quantity, the quality advantages and IBD observed here are still unlikely to be sufficient for maintenance of gynodioecy under nuclear inheritance of male sterility.
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260-3929, USA.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Dalton
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Koski
authors.forename: Tia-Lynn
authors.initials: TL
authors.lastname: Ashman
mesh_terms: D004777:Environment; D031985:Fragaria / Q000235:genetics* / Q000502:physiology; D057850:Hermaphroditic Organisms / Q000235:genetics / Q000502:physiology*; D007178:Inbreeding; D012098:Reproduction
keywords: Fragaria vesca subsp. bracteata; environmental variation; family-level variation; gynodioecy; inbreeding depression; maternal sex; strawberry