Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub


    Genetic load has been estimated for a number of outcrossing organisms, for example, Drosophila (Malogolowkin-Cohen et al. 1964), Tribolium (Levene et al. 1965), and man (Morton, Crow, and Muller 1956). However, little informaiton about load of deleterious genes in higher plants has been published. The purpose of this article is to provide some data on plants by reporting an estimate of embryonic load in coastal Douglas-fir as determined from comparison of set of sound seed following self-pollination and following controlled crossing with unrelated pollen.

    It was stated a decade ago (Dobzhansky 1957) that no estimates of frequency of deleterious and lethal genes were available for plants. This statement is still true in general, although some information does appear in the literature. For example, there are estimates or indications of load due to certain categories of genes in cultivated plants, especially genes causing chlorophyll deficiencies, as in maize (Crumpacker 1967) and pines (Eiche 1955; Snyder, Squillace, and Hamaker 1966). There are also data from some forest tree species, particularly coniferous species, which appear suitable for rough estimation of some part of the genetic load, although calculations of load have rarely been made (Fowler 1965b is an exception).

    The present data from coastal Douglas-fir were originally collected for purposes other than calculation of genetic load. However, the "control" appears good enough and the number of trees sampled large enough that a well-based estimate of load is possible. Because of this and because load estimates on plants are rare, the results from coastal Douglas-fir are presented in detail here.

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Sorensen, Frank C. 1969. Embryonic genetic load in coastal Douglas-fir, Pseudotsuga menziesii var. menziesii. American Naturalist. 103: 389-398

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page