Large differences in the composition of herbivore communities and seed damage in diploid and autotetraploid plant species
Abstrakt
Herbivory is one of the key interactions affecting plant fitness. Despite the large amount of data available on the effects of herbivores on various plant groups, we still know very little information about the interactions of herbivores with individuals having different ploidy levels.
We studied the relationship of diploid and tetraploid Centaurea phrygia in natural and experimental garden conditions to the community of pre-dispersal seed predators developing in flower heads of the plants. In addition, we collected a set of data on flowering phenology, and flower head morphology and chemistry to investigate potential mechanisms underlying the differences between cytotypes.
The two cytotypes are strongly differentiated in their flower head morphology and chemistry as well as in their flowering phenology, with flower heads of diploids being larger, containing more secondary metabolites and flowering later. Also, the two cytotypes strongly differed in the composition of insect communities in the flower heads and tetraploids suffered higher seed damage than the diploids.
The differences between cytotypes in seed damage were generally consistent across datasets, indicating that the differences are not due to differences in the habitats in which the cytotypes occur but are due to differences in particular biological characteristics of the plants. The diversity and composition of insect communities, however, strongly varied between years and environments.
Flowering phenology could explain part, but not all of the differences observed between cytotypes, indicating that other factors such as flower head morphology or chemistry could also play a role. The study indicated that the differences between the two cytotypes are important determinant of the plant-herbivore interactions in the system.
Although we identified multiple factors that could explain the different associations, further research is needed to assess the relative importance of each of these factors.