Summary
Measurement of outcrossing rates of ray (female) and disc (hermaphrodite) florets of radiate plants sampled from two polymorphic populations of Senecio vulgaris showed that ray florets outcross at much greater frequencies. In one population from Leeds, the greater recorded outcrossing of radiate relative to non-radiate plants (Marshall and Abbott, 1984) can be entirely accounted for by the higher outcrossing of ray florets in radiate capitula while, in a second population, from Cardiff, the difference is partly explained by the same effect. It is concluded that the possession of female ray florets and the resulting functional protogyny exhibited by radiate capitula (Burtt, 1977), are major causes of the reported difference in outcrossing frequency between radiate and non-radiate morphs in polymorphic populations of S. vulgaris. There are however, additional factors, the nature of which have not yet been determined, which may also contribute to the difference in some populations (e.g., at Cardiff), if not all polymorphic populations.
Similar content being viewed by others
Article PDF
References
Allard, R W, and Workman, P L. 1963. Population studies in predominantly self-pollinated species. IV. Seasonal fluctuations in estimated values of genetic parameters in lima bean populations. Evolution, 18, 470–480.
Burtt, B L. 1977. Aspects of diversification in the capitulum. In Heywood, V. H., Harbone, J. B. and Turner, B. L. The Biology and Chemistry of the Compositae. Vol. I, Academic Press, London, pp. 41–59.
Hedrick, P W. 1980. Hitch-hiking: A comparison of linkage and partial selfing. Genetics, 94, 791–808.
Ingram, R, and Taylor, L. 1982. The genetic control of a non-radiate condition in Senecio squalidus L. and some observations on the role of ray florets in the Compositae. New Phytol, 91, 749–756.
Ingram, R, Weir, J, and Abbott, R J. 1980. New evidence concerning the origin of inland radiate groundsel, Senecio vulgaris L. var hibemicus Syme. New Phytol, 84, 543–546.
Jain, S K. 1979. Estimation of outcrossing rates: some alternative procedures. Crop Sci, 19, 23–26.
Marshall, D F, and Abbott, R J. 1980. On the frequency of introgression of the radiate (Tr) allele from Senecio squalidus L. into Senecio vulgaris L. Heredity, 45, 133–135.
Marshall, D F, and Abbott, R J. 1982. Polymorphism for outcrossing frequency at the ray floret locus in Senecio vulgaris L. I. Evidence. Heredity, 48, 227–235.
Marshall, D F, and Abbott, R J. 1984. Polymorphism for outcrossing frequency at the ray floret locus in Senecio vulgaris L. II. Confirmation. Heredity, 52, 331–336.
Stace, C A. 1977. The origin of radiate Senecio vulgaris L. Heredity, 39, 383–388.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Marshall, D., Abbott, R. Polymorphism for outcrossing frequency at the ray floret locus in senecio vulgaris L. III. causes. Heredity 53, 145–149 (1984). https://doi.org/10.1038/hdy.1984.70
Received:
Issue Date:
DOI: https://doi.org/10.1038/hdy.1984.70
This article is cited by
-
Reproductive Biology of Asteraceae on Oceanic Islands
The Botanical Review (2023)
-
Recent hybrid origin and invasion of the British Isles by a self-incompatible species, Oxford ragwort (Senecio squalidus L., Asteraceae)
Biological Invasions (2009)
-
Reproductive isolation of a new hybrid species, Senecio eboracensis Abbott & Lowe (Asteraceae)
Heredity (2004)
-
Chloroplast DNA and isozyme evidence on the evolution ofSenecio vulgaris (Asteraceae)
Plant Systematics and Evolution (1997)
-
The influence of population density on outcrossing rates in Mimulus ringens
Heredity (1995)