title: Reproductive success through high pollinator visitation rates despite self incompatibility in an endangered wallflower.
abstract: OBJECTIVE
  Self incompatibility (SI) in rare plants presents a unique challenge-SI protects plants from inbreeding depression, but requires a sufficient number of mates and xenogamous pollination. Does SI persist in an endangered polyploid? Is pollinator visitation sufficient to ensure reproductive success? Is there evidence of inbreeding/outbreeding depression? We characterized the mating system, primary pollinators, pollen limitation, and inbreeding/outbreeding depression in Erysimum teretifolium to guide conservation efforts.
  
  
  METHODS
  We compared seed production following self pollination and within- and between-population crosses. Pollen tubes were visualized after self pollinations and between-population pollinations. Pollen limitation was tested in the field. Pollinator observations were quantified using digital video. Inbreeding/outbreeding depression was assessed in progeny from self and outcross pollinations at early and later developmental stages.
  
  
  RESULTS
  Self-pollination reduced seed set by 6.5× and quadrupled reproductive failure compared with outcross pollination. Pollen tubes of some self pollinations were arrested at the stigmatic surface. Seed-set data indicated strong SI, and fruit-set data suggested partial SI. Pollinator diversity and visitation rates were high, and there was no evidence of pollen limitation. Inbreeding depression (δ) was weak for early developmental stages and strong for later developmental stages, with no evidence of outbreeding depression.
  
  
  CONCLUSIONS
  The rare hexaploid E. teretifolium is largely self incompatible and suffers from late-acting inbreeding depression. Reproductive success in natural populations was accomplished through high pollinator visitation rates consistent with a lack of pollen limitation. Future reproductive health for this species will require large population sizes with sufficient mates and a robust pollinator community.
authors.affiliation: Department of Environmental Studies, San Jose State University, One Washington Square, San Jose, California 95192 USA.
authors.forename: Miranda K
authors.initials: MK
authors.lastname: Melen
authors.affiliation: Department of Biology, Santa Clara University, 500 El Camino Real, Santa Clara, California 95053 USA.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Herman
authors.affiliation: Southern Illinois University, 1125 Lincoln Drive, Carbondale, Illinois 62902 USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Lucas
authors.affiliation: Department of Environmental Studies, San Jose State University, One Washington Square, San Jose, California 95192 USA.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: O'Malley
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064 USA.
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Parker
authors.affiliation: Department of Biology, Santa Clara University, 500 El Camino Real, Santa Clara, California 95053 USA.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Thom
authors.affiliation: Department of Biology, Santa Clara University, 500 El Camino Real, Santa Clara, California 95053 USA jwhittall@scu.edu.
authors.forename: Justen B
authors.initials: JB
authors.lastname: Whittall
mesh_terms: D000818:Animals; D032601:Erysimum / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D005638:Fruit / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D000071422:Inbreeding Depression; D007313:Insecta / Q000502:physiology*; D011058:Pollen / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D053205:Pollen Tube / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D054817:Pollination; D011123:Polyploidy; D012098:Reproduction; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D057945:Self-Fertilization; D060436:Self-Incompatibility in Flowering Plants
keywords: Brassicaceae; Erysimum teretifolium; inbreeding depression; pollen limitation; self incompatibility