Close Encounters

Edge effects and mating patterns in a bumblebee-pollinated plant

Are plants on the edge of their population at a disadvantage when it comes to pollination?

Many flowering plant populations are small in size or have irregular shapes that increase the proportion of plants on the population’s edge. This reduces the number of neighbours a plant has, which may reduce mating opportunities and lead to decreased fitness. Plants that rely on area-restricted foraging pollinators, such as bumblebees, may be particularly vulnerable to edge effects. Previous work has quantified seed production and mate diversity for edge versus interior plants, however the effects of spatial position on pollination success and the extent of pollen-mediated gene dispersal have not previously been explored.

Bumblebee visiting a Mimulus ringens flower in the experimental population. Image credit: J. Karron.

In their new study published in AoBP, Christopher et al. examined whether fitness via male and female function as well as pollinator foraging patterns differed between plants on the edge or the interior of an experimental population of Mimulus ringens. They found no differences between fitness components. However, pollinator visitation rates were significantly lower for edge plants. This suggests that plant reproduction parameters respond independently to spatial location. The authors conclude that edge effects are not as strong as is commonly assumed and are restricted only to some aspects of pollination biology.

Researcher highlight

Dorothy Christopher and Maggie Hackl tracking bumblebees and marking visited flowers in an experimental population of Mimulus ringens.

Dorothy Christopher received her PhD from the University of Georgia and is currently a postdoctoral researcher at the University of Wisconsin – Milwaukee. Her research focuses on the ecology and evolution of plant mating systems. She combines genetic techniques, field work in natural populations, and greenhouse experiments to address questions in plant reproductive biology. She is particularly interested in how pollinator visitation and heritable plant traits interact to influence male and female fitness.

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