PhD thesisWe conducted an extensive flow cytometric survey of reproductive modes and genome sizes
(GSs), combined with cytotype screenings for 100 genera and 335 Asteraceae species across
elevation ranges in the Alps. We found that apomictic reproduction was tied to odd ploidy
levels (e.g. 3x, 5x) and showed strong phylogenetic signal, but did not correlate with elevation
or phenology. Most species analysed were diploid, with GSs skewed towards small values. Short
life cycles (annual or biennial) and endemic status were linked to smaller GSs, while elevation,
nitrogen soil content preference and phenology were not.
We analysed a sympatric mixed-ploidy population of Senecio doronicum, gathering ploidy and
phenotype data. We found divergent phenology between cytotypes, with octoploid specimens
flowering earlier than tetraploids. Also, cytotypes showed phenotype differences. Octoploids
were taller and had larger capitula with more florets, and tetraploids had more numerous
capitula with fewer florets and more pollen per floret. Likewise, cytotypes exhibited micro-niche
differences: octoploids occupied a larger niche and grew in denser communities, while tetraploids
occupied marginal habitats with sparse vegetation. Despite their abundance, reproductive
success was lower in octoploids, that suffered attacks by a pre-dispersal seed predator.
Available automated pollinator monitoring systems were reviewed, and one of such systems
(Rana) was deployed to monitor insect visits on S. doronicum. The main visitors were shorttongued
insects (flies and small bees), mostly hoverflies. Octoploids received less visits and
lower proportion of feeding visits than tetraploids. Most of the feeding visits to octoploids
were made by Syrphus and to tetraploids by Eristalis. Overall, each cytotype showed distinct
pollinators communities with similar extents of variation.
This thesis provides novel insights into how genomic processes, such as polyploidization, and
ecological processes, such as pollination, can shape plant diversity both at the local (sympatric
population micro-evolution) and geographical (Asteraceae family macro-evolution in the Alps)
scales.
