The ecological and genetic factors governing plant adaptation to environmental conditions are of fundamental interest in evolutionary biology, but also in plant breeding and conservation, and for predictions of response to environmental change. We use a combination of field experiments, new sequencing technology, and genomic approaches to study the functional and genetic basis of plant adaptation along climatic gradients, and the ecological and evolutionary consequences of plant-pollinator and plant-herbivore interactions. The aim is to identify both targets and agents of selection, and the genetic basis of adaptive evolution. This work includes studies of natural populations of the model plant Arabidopsis thaliana, but also of closely related plant species such as the perennial herbs A. lyrata and Arabis alpina. This research stands out internationally because of its reliance on powerful experimental approaches conducted at the sites of ecologically well characterized natural populations.
In one project, we use a unique genetic resource in the form of a large population of recombinant inbred lines (RIL) derived from a cross between two ecologically well characterized Arabidopsis thaliana populations that exhibit strong adaptive differentiation and that are located close to the northern and southern range margins in Europe. Our experiments are designed to
- identify traits and genomic regions subject to selection in the field and under experimental conditions,
- examine the genetic basis of differences in putative adaptive traits between populations,
- determine the extent to which phenotypic and genetic trade-offs constrain adaptation to different environments, and
- identify agents of selection in the native habitats.
As part of this research, the UCEG environment has sparked collaboration between the research groups of Ågren, Andersson and Baldauf. The aim of this parallel project is to examine the adaptive significance and genetic basis of differences between A. thaliana populations in terms of their interactions with the soil microbiome. One unique feature of this project is that it will allow us to explore the adaptive significance and genetic basis of differences in interactions with the microbiome under relevant field conditions, and thus test hypotheses regarding the importance of biotic interactions for adaptive evolution of plant populations.
A prominent floral display increases attractiveness to pollinators, but may also increase the risk of damage from seed predators and grazers. We use several species, including Arabidopsis lyrata, orchids and the primrose Primula farinosa, to examine factors governing the evolution of floral display. This research involves wide application of experimental approaches to identify targets and agents of selection in the field, and thus fills an important gap in our understanding of the processes shaping current selection regimes. With long-term field experiments, we have demonstrated that changes in selection exerted by biotic agents can trigger rapid evolutionary changes in natural plant populations.
Selected publications
Ågren, J., C. G. Oakley, J. K. McKay, J. T. Lovell, and D. W. Schemske. Genetic mapping of adaptation reveals fitness trade-offs in Arabidopsis thaliana. Proceedings of the National Academy of Sciences USA, in press.
Ågren, J., F. Hellström, P. Toräng, and J. Ehrlén. 2013. Mutualists and antagonists drive among-population variation in selection and evolution of floral display in a perennial herb. Proceedings of the National Academy of Sciences USA 110:18202-18207.
Sletvold, N., M. Mousset, J. Hagenblad, B. Hansson, and J. Ågren. 2013. Strong inbreeding depression in two Scandinavian populations of the self-incompatible perennial herb Arabidopsis lyrata. Evolution 67:2876-2888.
Sletvold, N., J. M. Grindeland, and J. Ågren. 2013. Vegetation context influences the strength and targets of pollinator-mediated selection in a deceptive orchid. Ecology 94:1236-1242.
Ågren, J., and D. W. Schemske. 2012. Reciprocal transplants demonstrate strong adaptive differentiation of the model organism Arabidopsis thaliana in its native range. New Phytologist 194:1112-1122.
Sandring, S., and J. Ågren. 2009. Pollinator-mediated selection on floral display and flowering time in the perennial herb Arabidopsis lyrata. Evolution 63:1292-1300.