title: Embryonic inbreeding depression varies among populations and by mating system in Witheringia solanacea (Solanaceae).
abstract: OBJECTIVE
  Embryonic inbreeding depression is a key influence on mating system evolution and can be difficult to estimate in self-incompatible species. A pollen chase experiment was used to estimate the magnitude of embryonic inbreeding depression in Costa Rican Witheringia solanacea, a species polymorphic for self-incompatibility (SI). In a pollen chase experiment, bud self-pollinations are followed after anthesis by outcross pollinations, with a comparable pair of outcross pollinations used as a control. Lowered seed set for the self-precedence treatment indicates embryonic inbreeding depression. •
  
  
  METHODS
  Embryonic inbreeding depression was assayed for self-compatible (SC) individuals and for SI plants from two populations that differ quantitatively in the onset and enzymatic activity of their SI response. Microsatellite markers were used to assay the selfing rate of a sample of surviving progeny from the prior self-pollination treatment. •
  
  
  RESULTS
  SC individuals showed no evidence of embryonic inbreeding depression. In SI plants, prior self-pollination reduced seed number by 28-70%, depending on population. Microsatellite genotyping revealed that embryonic inbreeding depression was even more severe than estimated by the phenotypic data: for mature fruits resulting from self-pollination precedence, the majority of the progeny were the result of outcross fertilization. •
  
  
  CONCLUSIONS
  Lineage-specific purging of recessive lethals has accompanied the evolution of SC in this species. SI populations show contrasting levels of embryonic inbreeding depression, with nearly complete embryonic lethality upon selfing in the Monteverde population. In the face of high embryonic inbreeding depression, an increase in selfing rate can evidently occur only under severe pollen limitation.
authors: Department of Biology, Colby College, Waterville, Maine 04901 USA.
authors: Judy L
authors: JL
authors: Stone
authors: Emily E
authors: EE
authors: Wilson
authors: Andrew S
authors: AS
authors: Kwak
references: Ann Bot. 2006 Aug;98(2):351-60
references: 16720632
references: Evolution. 1990 Aug;44(5):1230-1241
references: 28563887
references: Genetics. 2001 Nov;159(3):1217-29
references: 11729164
references: Evolution. 2005 Jan;59(1):46-60
references: 15792226
references: Genetics. 1995 Nov;141(3):1209-23
references: 8582625
references: Heredity (Edinb). 2005 May;94(5):547-55
references: 15770231
references: Evolution. 1985 Jan;39(1):24-40
references: 28563655
references: Evolution. 1999 Oct;53(5):1354-1365
references: 28565542
references: Evolution. 2002 Dec;56(12):2347-58
references: 12583575
references: Heredity (Edinb). 2001 Feb;86(Pt 2):184-94
references: 11380664
references: Evolution. 1996 Feb;50(1):54-70
references: 28568860
references: Methods Mol Biol. 2000;132:365-86
references: 10547847
references: Am J Bot. 2008 Dec;95(12):1596-605
references: 21628166
references: Am J Bot. 1999 Aug;86(8):1114-20
references: 10449390
references: Genetics. 2003 Dec;165(4):2193-212
references: 14704197
references: Genetics. 2004 Jun;167(2):1001-15
references: 15238548
references: Evolution. 2000 Jun;54(3):840-6
references: 10937257
references: Theor Appl Genet. 1990 Jun;79(6):825-32
references: 24226746
references: Heredity (Edinb). 2005 Feb;94(2):159-65
references: 15562289
references: Evolution. 2002 Nov;56(11):2187-95
references: 12487349
references: Am J Bot. 2006 Apr;93(4):592-8
references: 21646220
references: Evolution. 1999 Oct;53(5):1366-1376
references: 28565568
references: Heredity (Edinb). 2002 Feb;88(2):154-9
references: 11932774