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

• Published in: Philosophical transactions of the Royal Society of London. Series B. Biological sciences Vol. 358; no. 1434; pp. 1047 - 1050
• Main Authors: Brennan, Adrian C., Harris, Stephen A., Hiscock, Simon J.
• Format: Journal Article
• Language: English
• Published: England The Royal Society 29.06.2003
• Subjects: Allele; Alleles; Asteraceae; Ecological genetics; Evolution; Genes, Dominant - genetics; Genetic inheritance; Genetic loci; Genetics, Population; Inbreeding; Mate Availability; Mating behavior; Plants; Pollen; Population Bottleneck; Population estimates; Population genetics; Reproduction - genetics; S-allele; Senecio - genetics; Senecio squalidus; Sporophytic Self-Incompatibility; The Fluid Genome: Intraspecific Gene Flow; United Kingdom
• ISSN: 0962-8436; 1471-2970
• DOI: 10.1098/rstb.2003.1300

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.