The evolution of dispersal syndromes: a case study with the tribe Cichorieae (Asteraceae) (Visiting Scholar)
The fitness of any organism is conditioned by its dispersal behavior. In plants, dispersal distance and propensity are mainly determined by fruit characteristics. Some plants produce two or more defined fruit types, i.e heterocarpy, which differ in dispersal behavior. Such fruit polymorphism has been considered as a bet-hedging strategy to increase fitness under heterogeneous conditions. Moreover, the evolution of heterocarpy might be favored by the existence of other traits. Fruits are repeated organs whose attributes, such as size and rate of maturation are affected by position within a plant and even within individual inflorescences. Therefore, heterocarpy might evolve with higher likelihood in those plants that show strong positional variation in fruit traits. Additionally, genomic variation may alter the patterns of genetic regulation enhancing the adaptive potential of certain genomic architectures. For instance, polyploids might have a higher likelihood of developing morphological innovations, including fruit polymorphisms. In this project, I will assess the role of extrinsic (ecological niche) and intrinsic factors (phenotypic constraints, mating systems, ploidy level and genome size) leading to the evolution of heterocarpy in a large Asteraceae lineage, the tribe Cichorieae. This group is a good model for this aim because it is a well-studied and diverse plant group for which ecological, morphological, genetical and phylogentic data are available.