Magne Friberg lab
Floral scent evolution in ecological networks
The same signals that attract pollinators can be picked up also by herbivores and seed predators. Local variation in these networks is likely to be an important driver of geographical variation in plant signaling. We use several model systems, including different populations of the crucifer plants Arabis alpina and Arabidopsis lyrata. In these species, several populations have evolved self-compatibility. These populations also show substantial variation in floral morphology and chemical floral signaling, and provide interesting model systems for understanding the relationship between different floral signals, the plant mating system and the local community of associated insects.
Coevolutionary divergence in tight mutualisms
Obligate relationships between prodoxid moths and their host plants are among the best-studied examples of coevolution in nature. The moth Greya politella simultaneously pollinates and lays eggs into the flowers of its Lithophragma host plants (Saxifragaceae). We study the evolution of floral scent variation, and its importance for interaction specificity and population and species divergence among both the plants and the insects. Further, we compare the impact of selection from the specific moth pollinators with the evolutionary effects of generalized co-pollinators at various geographic scales.
Plant genome duplications and the evolution of plant-insect interactions
Diversification requires processes that generate diversity (mutation, recombination) and processes that filter this diversity (drift, natural selection). In plants, the most dramatic form of mutation is polyploidization, the duplication of the chromosome set. We investigate the direct effects of polyploidization on phenotypic traits of importance for plant-insect interactions (e.g. floral scent and morphology), using different ploidy-types of the plant Lithophragma bolanderi as model. This species involves multiple ploidy-levels, and different populations are highly variable in floral scent and morphology, and in the propensity to form asexual propagation bodies (root bulbils). Ecology may interact with genomic architecture if pre-existing selection for asexuality facilitates establishment of polyploid lineages; e.g., in conditions where pollination is unreliable, selection should favour asexual reproduction also in diploid populations. Thus, the success of novel polyploids may depend on plant-insect interactions. We combine genomic methods with greenhouse experiments and ecological field studies to address how ecological processes and genomic architecture interact to shape resource allocation into sexual and asexual reproduction, and how this variation facilitates the origination of ploidy-level variation.
Evolution of host plant preferences
Whereas plant signals are partly shaped by the need to avoid attacks from insect antagonists, the fitness of phytophagous insects is largely a result of how well the female succeeds in finding suitable hosts for her offspring. We use two closely related butterflies (Pieris napi and Pieris rapae), at different levels of host specialization, to study the evolutionary potential of host plant preferences, and how these relate to female experience, plant growth form and the composition of the host plant community. We use repeatable and reliable bioassays to determine patterns of local adaptations in host plant use. The current project explores how local selection can affect female egg-laying preferences, and how this relate to the landscape-level land use in each area.