Title: Pollinator behavior mediates negative interactions between two congeneric invasive plant species
What happens when more than one exotic species
invades a new place? Much research has focused on the negative effects of exotic
invasive species on native species, but a recent study establishes that invasive
species can also negatively affect each other. In an experiment conducted at the
Penn State Rock Springs Research Farm, Suann Yang, Matt Ferrari, and Katriona
Shea grew two species of invasive thistle together and alone. They discovered
that when the two thistle species were together, both species reproduced less
than when each was alone. They attribute this reduced reproduction to the insect
pollinators that they share.
Sharing pollinators means that more attractive plant species might steal
pollinators away from less attractive plant species. But how pollinators move
around is also important, and the makeup of the plant community can affect this
movement. "In the mixed patches, the pollinators behaved differently. They
tended to spend more time moving around an individual plant than from plant to
plant," said Suann Yang. Thus, exotic invasive species have the potential to
interfere with each other's ability to invade a new place, both by diverting
pollinators and by altering the way pollinators behave. As more habitats are
invaded by more exotic species, their effects on each other should not be
ignored when estimating how quickly they will be able to invade.
Reference: Suann Yang, Matthew J. Ferrari, &
Katriona Shea (2010). Pollinator behavior mediates negative interactions between
two congeneric invasive plant species. The American Naturalist,
v177.
