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
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.
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.