Pollination is a critical ecosystem service, and over 90% of flowering plants require animals for pollination. However, like many other interspecies interactions this service is being disrupted by anthropogenic activities, such as the introduction of alien species (Cane & Tepedino 2001). Humans are moving species around the world at unprecedented rates, and invasive alien species are one of the largest threats to global biodiversity. recent studies have begun to investigate their impact on plant-pollinator interactions (Chittka & Schurkens 2001). These studies are mostly limited to interactions between a pair of plant species and their pollinators (Brown& Mitchell 2001), however, plant-pollinator interactions typically involve a large number of species, and therefore studies at the community level are most appropriate for understanding the pollination ecology of alien plants.

In the late 1800's entomologist Charles Robertson documented all the plant-pollinator interactions in Carlinville, Illinois. His data consists of over 15,000 plant-pollinator interactions, and provides an unprecedented opportunity to revisit the area and compare current interactions with historical ones. Robertson's historic dataset shows that alien plants were visited by fewer pollinators and were less integrated into the network of plant-pollinator interactions than native plants (Memmott & Waser 2002). Additionally, species that were phylogenetically novel (lacking native congeners) were visited by fewer pollinators than their less novel counterparts (Memmott & Waser 2002). Robertson's study was conducted 75 years after European colonization when alien species were likely first introduced to Carlinville. Over a century has passed since then, and the area has been invaded by more alien plants (new aliens) that now share the habitat with the original alien plants (old aliens) as well as natives. In my research, I am resampling a subset of the plant-pollinator interactions in Carlinville to determine how pollinator interaction patterns of old aliens have changed over time, and if phylogenetic novelty or breeding system plays a role in the degree to which new and old aliens are integrated into the pollination network.

I hypothesize that the old aliens will now be more integrated into the pollination network than they were historically, and that new aliens will be less integrated compared to old aliens. However, I also expect to see variation in degree of integration within alien groups. I hypothesize that phylogenetically novel aliens will be less integrated into the pollination network compared to less novel ones because they may not be as readily recognized by native pollinators. Additionally, aliens with an autogamous breeding system (the ability to self-fertilize) will be less integrated compared to aliens that are self incompatible and require pollinator service to set seed.

By re-examining historic plant-pollinator interactions of alien plants in Carlinville, this project will provide unique insight into how alien plant species integrate into plant-pollinator networks over a long time period. This is a key area of invasive plant ecology that has not been addressed previously due to the lack of historical information about plant-pollinator interactions at different stages of plant invasion. The results of this study will allow us to better predict how new alien invasions may disrupt native pollination networks after a long time period. As a part of a larger ongoing study documenting the entire plant-pollinator web including native species, this project will also contribute to understanding how alien plants integrate themselves into native pollinator webs by potentially usurping links previously connected to native plants.

Works Cited
Brown BJ, Mitchell RJ (2001). Competition for pollination: effects of pollen of an invasive plant on seed set of a native congener. Oecologia 129:43-49.

Cane JH, and Tepedino VJ (2001). Causes and extent of declines among native North American invertebrate pollinators: detection, evidence, and consequences. Conservation Ecology 5(1): 1.

Chittka L, Schurkens S (2001). Successful invasion of a floral market. Nature 441, 653.

Memmott J, Waser NM (2002). Integration of Alien Plants into a Native Flower-Pollination Visitation Web. Proceedings: Biological Sciences 269:1508:2395-2399.

Robertson C (1929). Flowers and Insects: lists of visitors to four hundred and fifty-three flowers. Carlinville, IL: C, Robertson.