Mutualisms in a changing world: an evolutionary perspective.
ABSTRACT Ecology Letters (2010) 13: 1459-1474 ABSTRACT: There is growing concern that rapid environmental degradation threatens mutualistic interactions. Because mutualisms can bind species to a common fate, mutualism breakdown has the potential to expand and accelerate effects of global change on biodiversity loss and ecosystem disruption. The current focus on the ecological dynamics of mutualism under global change has skirted fundamental evolutionary issues. Here, we develop an evolutionary perspective on mutualism breakdown to complement the ecological perspective, by focusing on three processes: (1) shifts from mutualism to antagonism, (2) switches to novel partners and (3) mutualism abandonment. We then identify the evolutionary factors that may make particular classes of mutualisms especially susceptible or resistant to breakdown and discuss how communities harbouring mutualisms may be affected by these evolutionary responses. We propose a template for evolutionary research on mutualism resilience and identify conservation approaches that may help conserve targeted mutualisms in the face of environmental change.
Article: Intercontinental differences in resource use reveal the importance of mutualisms in fire ant invasions.[show abstract] [hide abstract]
ABSTRACT: Mutualisms play key roles in the functioning of ecosystems. However, reciprocally beneficial interactions that involve introduced species also can enhance invasion success and in doing so compromise ecosystem integrity. For example, the growth and competitive ability of introduced plant species can increase when fungal or microbial associates provide limiting nutrients. Mutualisms also may aid animal invasions, but how such systems may promote invasion success has received relatively little attention. Here we examine how access to food-for-protection mutualisms involving the red imported fire ant (Solenopsis invicta) aids the success of this prominent invader. Intense interspecific competition in its native Argentina constrained the ability of S. invicta to benefit from honeydew-producing Hemiptera (and other accessible sources of carbohydrates), whereas S. invicta dominated these resources in its introduced range in the United States. Consistent with this strong pattern, nitrogen isotopic data revealed that fire ants from populations in the United States occupy a lower trophic position than fire ants from Argentina. Laboratory and field experiments demonstrated that honeydew elevated colony growth, a crucial determinant of competitive performance, even when insect prey were not limiting. Carbohydrates, obtained largely through mutualistic partnerships with other organisms, thus represent critical resources that may aid the success of this widespread invasive species. These results illustrate the potential for mutualistic interactions to play a fundamental role in the establishment and spread of animal invasions.Proceedings of the National Academy of Sciences 12/2011; 108(51):20639-44. · 9.68 Impact Factor