The population genetics of sporophytic self-incompatibility in Senecio squalidus L. (Asteraceae): avoidance of mating constraints imposed by low S-allele number.

Journal article

Senecio squalidus L. (Asteraceae) has been the subject of several ecological and population genetic studies due to its well-documented history of introduction, establishment and spread throughout Britain in the past 300 years. Our recent studies have focused on identifying and quantifying factors associated with the sporophytic self-incompatibility (SSI) system of S. squalidus that may have contributed to its success as a colonist. These findings are of general biological interest because they provide important insights into the short-term evolutionary dynamics of a plant mating system. The number of S-alleles in populations and their dominance interactions were investigated in eight wild British populations using cross-diallel studies. The numbers of S-alleles in British S. squalidus populations are typically low (average of 5.3 S-alleles) and the entire British population is estimated to possess no more than 7-11 S-alleles. Such low numbers of S-alleles are most probably a consequence of population bottlenecks associated with introduction and colonization. Potential evolutionary impacts on SSI caused by a paucity of S-alleles, such as restricted mate availability, are discussed, and we suggest that increased dominance interactions between S-alleles may be an important short-term means of increasing mate availability when S-allele numbers are low.

Authors: Brennan, A; Harris, S; Hiscock, S

• Publication status: Published
• Journal: Philosophical transactions of the Royal Society of London. Series B, Biological sciences
• Volume: 358
• Issue: 1434
• Pages: 1047-1050
• Publication date: 2003-06-01
• DOI: 10.1098/rstb.2003.1300
• EISSN: 1471-2970
• ISSN: 0962-8436
• Language: English
• Keywords: Senecio; Reproduction; Alleles; Inbreeding; Genetics, Population; Great Britain; Genes, Dominant