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Inbreeding depression and the outcrossing rate in natural populations of Allium schoenoprasum L. (wild chives)

Heredity volume 60, pages 257261 (1988) | Download Citation



The level of inbreeding depression has been measured at four independent stages of the life cycle (parental seed fecundity, seed viability, seedling survival and seedling growth rate) using wild-collected parental plants from seven natural populations of Allium schoenoprasum. At each stage, progenies produced by self-fertilisation were significantly less fit than progenies produced by cross-fertilisation, and the overall inbreeding depression was severe (0·718). This suggests that a high level of cross-fertilisation usually occurs in natural populations, despite the fact that A. schoenoprasum is a clonal, self-compatible, hermaphrodite plant, with apparently ample opportunities for geitonogamous selfing.

Using a white flower colour marker, the minimum outcrossing rate in a natural population has been estimated as 0·91. However, this is almost certainly an over-estimate due to the unequal viabilities of cross and self zygotes. An adjusted estimate of tmin = 0·80 is derived which takes account of the lower survival rate of self zygotes


  1. 1985. Maintenance of a polymorphism for out-crossing frequency in a predominantly selfing plant. In Haeck, J. and Woldendorp J. W. (eds.) Structure and Functioning of Plant Populations, 2, North-Holland Publishing Co., Amsterdam, pp. 277–286.

  2. 1968. Evolution in closely adjacent plant populations. V. Evolution of self-fertility. Heredity, 23, 219–238.

  3. 1984. Influence of flower color polymorphism on genetic transmission in a natural population of the common morning glory, Ipomoea purpurea. Evolution, 38, 796–803.

  4. 1979. The evolutionary genetics of sexual systems in flowering plants. Proc R Soc Lond, Ser B, 205, 513–530.

  5. 1876. The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom. Murray, London.

  6. 1972. Genetic load in loblolly pine. Am Nat, 106, 262–265.

  7. 1971. Embryonic lethals of Picea abies and Pinus sylvestris. Comm Inst For Fenn, 75, 1–30.

  8. 1985. The evolution of self-fertilization and inbreeding depression in plants. I. Genetic models. Evolution, 39, 24–40.

  9. 1984. Inbreeding depression and proximity-dependent crossing success in Phlox drommondii. Evolution, 38, 116–127.

  10. 1979. Some reproductive factors affecting the selection of self-fertilization in plants. Am Nat, 113, 67–79.

  11. 1971. Extreme-environment heterosis and genetic loads. Heredity, 26, 479–483.

  12. 1983. Breeding system and habitat effects on fitness components in three neotropical Costus (Zingi-beraceae). Evolution, 37, 523–539.

  13. 1985. The evolution of self-fertilization and inbreeding depression in plants. II. Empirical observations. Evolution, 39, 41–52.

  14. 1983. Relative fitnesses of selfed and outcrossed progeny in Gilia achilleifolia (Polemoniaceae). Evolution, 37, 292–301.

  15. 1969. Embryonic genetic load in coastal Douglasfir, Pseudotsuga menziesii var. menziesii. Am Nat, 103, 389–398.

  16. 1984. Seed variation in wild radish: effects of seed size on components of seedling and adult fitness. Ecology, 65, 1105–1112.

  17. 1985. The meiotic and breeding systems of Allium schoenoprasum L. in natural populations. D. Phil, thesis, University of York.

  18. 1987. Genetic analysis of flower colour variation in Allium schoenoprasum L. (wild chives). Heredity, 60, 253–256.

  19. 1968. Outcrossing in natural populations: a comparison of outcrossing estimation methods. In Drake, E. T. (ed.) Evolution and Environment, Yale Univ. Press, New Haven, pp. 369–385.

  20. 1971. Statistical Principles in Experimental Design, 2nd ed. McGraw-Hill Book Co., New York.

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    • J P Stevens

    Present address: Department of Botany and Microbiology, University College of Swansea, Singleton Park, Swansea SA2 8PP, UK.


  1. Department of Biology, University of York, York YO1 5DD, UK

    • J P Stevens
    •  & S M Bougourd


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