Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-28T01:56:06.235Z Has data issue: false hasContentIssue false
  • English
  • Français

Natural Selection During Germination in Wild Oat (Avena fatua) and California Burclover (Medicago polymorpha var. vulgaris) Populations

Published online by Cambridge University Press:  12 June 2017

S.K. Jain  and
K.N. Rai
S.K. Jain
Affiliation:
Dep. of Agron. and Range Sci., Univ. of California, Davis, CA 95616
K.N. Rai
Affiliation:
Dep. of Agron. and Range Sci., Univ. of California, Davis, CA 95616
Get access Rights & Permissions [Opens in a new window]

Abstract

Wild oat (Avena fatua L.) and California burclover [Medicago polymorpha L. var. vulgaris (Benth.) Shinners] are two important ruderal as well as rangeland species in California, with their wide adaptability correlated with several widespread genetic polymorphisms. In order to clearly demonstrate the role of genetic variation in their population dynamics, natural selection was studied at two of the polymorphic loci (B/b in wild oat and D/d in California burclover) which represent a useful class of marker genes governing seed coat morphology. Since parental seed coat often remains attached to the offspring seedling, two generations can be scored simultaneously during the population census in successive stages of the life cycle. Data are presented to provide direct evidence for natural selection at these loci and to argue for their wider use in such population studies. In wild oat, black lemma class (B-) germinated at a significantly higher rate than the gray class (bb) in mesic patches at one of the sites and seemed to be negatively density-dependent whereas density-dependent reproductive rates generally favored the gray class. Similarly, germination and seed output provided the balancing selection to maintain polymorphism at locus D/d in California burclover. Such processes of localized selection and population regulation may have significant implications in the management of weed populations.

Type
Research Article
Information
Weed Science , Volume 25 , Issue 6 , November 1977 , pp. 495 - 498
Copyright
Copyright © 1977 by the Weed Science Society of America 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

1. Baker, H.G. 1974. The evolution of weeds. Ann. Rev. Ecol. Syst. 5:1–24.Google Scholar
2. Cohen, D. 1968. A general model of optimal reproduction in a randomly varying environment. J. Ecol. 56:219–228.CrossRefGoogle Scholar
3. Evans, R.A. and Young, J.A. 1970. Plant litter and establishment of alien annual species in rangeland communities. Weed Sci. 18:697–703.Google Scholar
4. Evans, R.A., Young, J.A., and Kay, B.L. 1974. Germination of winter annual species from a rangeland community treated with paraquat. Weed Sci. 11:185–187.Google Scholar
5. Harper, J.L., Lovell, P.H., and Moore, K.G. 1970. The shapes and sizes of seeds. Ann. Rev. Ecol. Syst. 1: 327–356.Google Scholar
6. Harper, J.L. and White, J. 1974. The demography of plants. Ann. Rev. Ecol. Syst. 5:419–463.Google Scholar
7. Jain, S.K. 1969. Comparative ecogenetics of Avena fatua and A. barbata occurring in Central California. Evol. Biol. 3:73–118.Google Scholar
8. Jain, S.K. 1975. Patterns of survival and microevolution in plant populations. In: Karlin, S. and Nevo, E. (eds.) Population Genetics and Ecology, pp. 49–79. Academic Press, New York.Google Scholar
9. Jain, S.K. and Marshall, D.R. 1968. Genetic changes in a barley population analyzed in terms of life cycle components of selection. Genetica (The Hague) 38:355–374.Google Scholar
10. Johnson, C. 1976. Introduction to Natural Selection. Pennsylvania Univ. Press. 200 pp.Google Scholar
11. Levins, R. 1968. Evolution Under Changing Environments. Princeton Univ. Press. 120 pp.Google Scholar
12. Lewontin, R.C. 1974. The Genetic Basis of Evolutionary Change. Columbia, New York. 346 pp.Google Scholar
13. Marshall, D.R. and Jain, S.K. 1970. The role of seed predation and dormancy in the regulation of Avena populations. Ecology 51:886–891.CrossRefGoogle Scholar
14. Sheldon, J.C. 1974. The behavior of seeds in soil. III. The influence of seed morphology and the behavior of seedlings on the establishment of plants from surface-lying seeds. J. Ecol. 62:47–66.Google Scholar
15. Singh, R.S. and Jain, S.K. Analysis of selection at aleurone color loci in barley. Euphytica (in press).Google Scholar
16. Young, J.A., Evans, R.A., and Kay, B.L. 1973. Temperature requirements for seed germination in an annual-type rangeland community. Agron. J. 65:656–659.CrossRefGoogle Scholar