I am interested in the ecological and evolutionary consequences of plant-animal interactions, and in particular, the role of pollinators in driving floral evolution and plant population differentiation. I am also interested in how climate and land use affect plant population viability and evolution, both via direct effects on demographic rates and via effects mediated by biotic interactions.
Understanding adaptive evolution requires insight in the phenotypic traits subject to selection and the ecological factors that cause selection, something which remains a challenge in most cases.
In a couple of systems, we use field experiments to gain a quantitative understanding of the role of pollinators relative to other selective agents in shaping selection on floral traits. The adaptive significance of floral traits is examined through phenotypic manipulations, and the selective agents on floral traits are identified through manipulations of the pollination environment. A goal is to link phenotypic selection gradients with demographic data, to quantify lifetime contribution from specific selective agents and predict evolution in natural populations.
Manipulating the pollination environment of Gymnadenia conopsea by conducting hand-pollinations and selective pollinator exclusions (caging by day or night). Sølendet, Norway.
Many plants are currently red-listed, and populations are becoming small and fragmented. It is of great concern to determine demographic and genetic factors influencing extinction risk. We currently work with long-term data-series on orchid demography, where we combine monitoring in natural and managed field populations with experimental approaches targeted at the most uncertain life cycle transitions (germination and dormancy).
We also study the effects of pollen limitation and inbreeding through controlled crosses and field germination experiments, and the goal is to produce knowledge that will underpin management decisions and future conservation strategies for several declining species.
Sletvold N., J. M. Grindeland, P. Zu and J. Ågren. 2012. Strong inbreeding depression and local outbreeding depression in the rewarding orchid Gymnadenia conopsea. Conservation Genetics, doi: 10.1007/s10592-012-0373-7
Sletvold N., J. Trunschke, C. Wimmergren and J. Ågren. 2012. Separating selection by diurnal and nocturnal pollinators on floral display and spur length in Gymnadenia conopsea. Ecology, doi: 10.1890/11-2044
Sletvold N. and J. Ågren. 2011. Nonadditive effects of floral display and spur length on reproductive success in a deceptive orchid. Ecology 92: 2167-2174.
Sletvold N., J. M. Grindeland and J. Ågren. 2010. Pollinator-mediated selection on floral traits and flowering phenology in the deceptive orchid Dactylorhiza lapponica. New Phytologist 188: 385-392.
Sletvold N., D.-I. Øien and A. Moen. 2010. Long-term influence of mowing on population dynamics in the rare orchid Dactylorhiza lapponica: the importance of recruitment and seed production. Biological Conservation 143: 747-755.