I am an evolutionary ecologist whose research ranges from basic bee and pollination biology to conservation biology and agricultural pollination. I am interested in the interactions of flower visitors and the floral hosts which they often pollinate. I explore questions about pollinators, flowering plants and pollination from a variety of perspectives and at different scales from the foraging of individual bees, to the persistence of their populations, to the stability and dynamics of their communities in space and time.
Pollinators, pollination and landscape change
Much of my current research examines how landscape change affects native bees and the pollination they provide to wild and managed plant populations. Throughout these investigations I attempt to identify mechanisms that underlie the patterns we see at the level of communities across landscapes.
Current projects include:
- The importance of landscape connectivity for the persistence of pollinators in the mosaic landscapes associated with agriculture. This work uses a combination of field manipulations and spatially explicit modeling of resources across the landscape. Rather than adopting a habitat -non-habitat dichotomy, I view these landscapes as mosaics of different habitats of varying quality with respect to different resources such as floral resources and nesting sites. Connectivity among complementary habitat types may therefore be critical to population persistence.
- The effect of different ecological and life history traits on bee responses to habitat degradation and landscape modification. Analyses explore differential responses of bees to agricultural intensification and habitat restoration.
- The temporal and spatial variation of insect-flower interactions at the community level and how these webs (bi-partite networks) are affected by habitat type.
- Spatial and temporal stability in pollinator communities and pollination service
RESTORATION OF Pollinator Habitat
This research program seeks to identify mixtures of native forb species whose flowers best support abundant and diverse pollinators within agricultural landscapes.
Funding is through National Fish and Wildlife Foundation in collaboration with support from Operation Pollinator (Syngenta)
Phase 1. Testing different plant mixes for attractiveness to pollinators.
Phase 2. Testing ability of a “best mix” to support diverse pollinators over the growing season. Identify whether large scale plantings of the mix can enhance pollination service to adjacent crops under large-scale cultivation. Determine best methods for cultivation and management within the context of a production farm.
We want our approach to be one that farmers can practically adopt and that can effectively enhance pollinator numbers and diversity without increasing pest pressure.
Photos of Mixes during the 2011 Season.
Note seed watermelon field with some border weeds to the left in the photograph. By August early season flowers in the forb mix to the right have died back and later season sunflowers and gumweed dominates
Foraging specialization versus specialist pollinators
Another major interest of mine is in the ecology and evolution of trophic specialization by bees and how differences in specialization by these foragers affects their quality as pollinators and thus their potential influence on floral evolution. My approach to such pollination interactions embraces the idea that bees are nectar-and-pollen-eaters rather than simply pollinators. Their behavior at the level of individual flower interactions, movements among flowers, choices of host individuals and use of different host species is influenced by current ecological context and by selection for efficient foraging rather than for pollen transfer. The flowering plants from which these bees feed are selected to manipulate bee foragers to affect efficient pollen transfer.
Contributions of specialist and generalist pollinators
Plant species are often visited by combinations of specialist (oligolectic) and generalist (polylectic) bees. Although specialists may be superior pollinators because of fidelity to their host plant, they should be selected for efficient foraging on their host, but not for particularly effective pollen transfer. This means they might remove pollen from the system making them potentially inefficient pollinators or even pollen thieves. We are investigating pollen transfer dynamics by specialist and generalists bees that share the same host. This work is ongoing in Chihuahuan desert and in Mid-Atlantic woodland. Focal plant species include desert mallow, Opunita cacti, spring beauty and others.