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  • Gynodioecy  (2)
  • Breeding system  (1)
  • Springer  (3)
  • American Institute of Physics (AIP)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 71 (1985), S. 292-299 
    ISSN: 1432-2242
    Keywords: Breeding system ; Population subdivision ; Multilocus estimator ; Inbreeding ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The breeding systems of seven Limanthes (Limanthaceae) populations, including one “inbreeding” and three “outbreeding” taxa, were quantified using a multilocus outcrossing rate estimator (tm) and autofertility estimates. Along with the assays of heterozygosity levels, these data were used to separate components of “effective” outcrossing in terms of Wright's equilibrium inbreeding coefficient (Fe) and adult (FA) and zygotic (FZ) fixation indices. The patchy distribution of alleles as a potential source of “substructure inbreeding” was tested from the allelic frequencies mapped along a linear transect. Evidence for consanguineous matings in restricted neighborhoods and for selection at two different life cycle stages, and the efficiency of the protandrous breeding system were noted and discussed. Multilocus estimates of outcrossing are useful for their greater precision and unbiased nature while single locus estimates can help in detecting the effects of selection and population substructure. The data generally support the “heterozygosity paradox” noted by Brown (1979) but further suggest that the paradox may often result from a lack of precision of outcrossing estimates and from overlooking the stages of the life cycle being sampled.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 84 (1992), S. 155-160 
    ISSN: 1432-2242
    Keywords: Gynodioecy ; Colonizing species ; Mating system ; Isozymes ; Population structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A multilocus procedure was used to estimate outcrossing rates in ten roadside populations of Trifolium hirtum in California. Three groups of populations were studied: cultivars, hermaphroditic, and gynodioecious (sexually dimorphic) populations. The multilocus outcrossing rate (tm) varied from 0.05 to 0.43 among populations. Population level tm estimates were significantly correlated with the observed heterozygosity in gynodioecious populations but not in hermaphroditic populations. The outcrossing rate of hermaphrodites and females was estimated in three gynodioecious populations; the estimates of tm varied from 0.09 to 0.23 for hermaphrodites and from 0.73 to 0.80 for females. The distribution of outcrossing rates in gynodioecious populations is bimodal. Our results indicate that for the levels of selfing observed among hermaphrodites, inbreeding depression is likely to be a major factor in the maintenance of females in gynodioecious populations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 85 (1992), S. 153-161 
    ISSN: 1573-6857
    Keywords: Gynodioecy ; inheritance of male sterility ; nucleocytoplasmic differentiation ; Trifolium hirtum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inheritance of male sterility was studied using a set of intra and interpopulation crosses from Californian populations of rose clover (Trifolium hirtum All.). The F2 gave higher frequencies of male steriles in interpopulation crosses than in intrapopulation crosses. Several F2 families gave ratios that were compatible with models of two and three complementary genes. However, the frequency distribution of male sterility among F3 families rejected such models. Given that single and two gene models were rejected, we interpret the results using a cytoplasmic-nuclear model with more than two restorer loci which is at least consistent with the observed results.
    Type of Medium: Electronic Resource
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