Øystein Opedal lab
Plant Ecology and Evolution
The ecology and evolution of plant mating systems
Plants exhibit remarkably diverse sexual systems that range from obligate selfing to enforced outcrossing through self-incompatibility, separate sexes, or spatial or temporal separation of sex function within bisexual flowers. Among self-compatible species, most exhibit mixed mating systems, in which a proportion s of offspring are produced through self-fertilization, and a proportion t = 1 – s through outcrossing. Using the tropical vine Dalechampia as a model system, we are assessing which ecological factors (e.g. pollination reliability, intensity of seed predation) drive the evolution of mating systems among populations.
Understanding pollinator-mediated reproductive interactions
Whenever plant species that share pollinators flower together, there is scope for plant-plant interactions mediated by pollinators. These reproductive interactions can have direct fitness consequences for each plant species, and may affect the assembly of communities. The coflowering community may also affect patterns of natural selection on each species, and thus drive evolution of flowers and whole-plant phenotypes. We are currently looking for students interested in working on these issues!
The Dynamics of Complex Terrains
The environments inhabited by natural populations are not homogeneous, but vary at scales ranging from continents to centimetres. Alpine landscapes, for example, are often very heterogeneous due to the complex topography characteristic of mountain landscapes. Environmental heterogeneity associated with topographic complexity have myriad consequences for the organisms inhabiting these environments, not least their ability to persist when the environment is changing. Populations can respond to environmental change in two basic ways: either stay where you are and adjust or adapt to novel environmental conditions, or migrate to track favourable environments elsewhere. Populations that fail to do so are likely to go extinct due to competition from well-adapted invaders. We have been interested in how topographically complex landscapes differ from more homogeneous ones. One consistent pattern is that complex landscapes tend to contain more species, most likely due to the greater range of microenvironments available on complex landscapes. Furthermore, complex landscapes tend to be more variable in space, so that when walking across the landscape, you will tend to encounter more different species. In ecological terms, complex landscapes are characterized by greater beta-diversity. Why does this matter for populations experiencing environmental change? The first reason is that migrating to a new spot that is, say, 2 degrees cooler on average is easier if that spot is 10 meters away than if it is 1 kilometre away, at 300 meters higher altitude. Thus, complex landscapes may allow persistence of local populations through reshuffling of species on the landscape. A second reason is that populations occupying complex landscapes may differ genetically from those occupying more homogeneous ones. For example, environmental heterogeneity is thought to select for phenotypic plasticity; the ability of a genotype to produce different phenotypes depending on environmental conditions. Furthermore, environmental heterogeneity could select for greater genetic diversity and thus greater abilities to respond to further environmental change.