Abstracts (first author)
Floral pigmentation evolution and movement through genetic space in snapdragons (Antirrhineae)
Floral pigmentation is a conspicuous and variable trait with an enormous effect on sexual selection, and the underlying genetic pathways are well-understood. As such, flower colour evolution has great potential to inform our understanding of the relationship between genes and phenotype. Previous work has found consistent patterns of irreversible transitions from purple to white, red and blue flowers, via single-locus loss-of-function mutations in regulatory genes of the flavonoid pathway. Since yellow pigmentation is typically controlled by a wholly different pathway, transitions to yellow must involve mutations at two loci. However, transitions involving yellow flowers, or at broader taxonomic scales have never been properly examined. I present results from an ongoing comparative study of floral evolution in a tribe of snapdragons (Antirrhineae, Plantaginaceae), which aims to assess patterns of evolution between yellow, white and purple flowered species in a phylogenetic context. Single locus transitions appear to dominate at short time scales, demonstrating the need to look beyond the genus level. Transitions also appear to be generally more reversible than in previously examined groups. I also examine the role of other floral traits that may be correlated with shifts in flower colour.
Mating patterns and sexual selection in a snapdragon hybrid zone
Large scale, long term evolutionary processes such as gene flow, drift or species formation depend ultimately on the patterns of mating between individual organisms. Mating patterns are especially interesting in natural hybrid zones, where alleles from parental populations recombine to form novel genotype combinations. In the Spanish Pyrenees, one yellow- and one magenta-flowered subspecies of the snapdragon Antirrhinum majus form such a hybrid zone, leading to floral colours not seen in either subspecies. Complementing a broader study to assign parentage across generations, I am genotyping wild seedlings to assign paternity to candidate fathers. This information can be used to infer the ways in which pollinators mediate the dispersal of gametes, and the effects of multiple mating on the distribution of siring success of different fathers with a single mother.