Species Response to Environmental Change: Impacts of Food Web Interactions and Evolution
Jason P. Harmon,1*
Nancy A. Moran,2
Anthony R. Ives1
How environmental change affects species abundances depends
on both the food web within which species interact and their
potential to evolve. Using field experiments, we investigated
both ecological and evolutionary responses of pea aphids (
Acyrthosiphon pisum), a common agricultural pest, to increased frequency of
episodic heat shocks. One predator species ameliorated the decrease
in aphid population growth with increasing heat shocks, whereas
a second predator did not, with this contrast caused by behavioral
differences between predators. We also compared aphid strains
with stably inherited differences in heat tolerance caused by
bacterial endosymbionts and showed the potential for rapid evolution
for heat-shock tolerance. Our results illustrate how ecological
and evolutionary complexities should be incorporated into predictions
of the consequences of environmental change for species' populations.
2 Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
* To whom correspondence should be addressed. E-mail: jharmon{at}wisc.edu
