What is Community Genetics?

Antonovics (1992) articulated a vision for a new field of inquiry, Community Genetics, to investigate the ìrole of genetic variation in influencing species interactions and determining community structure.î Community genetics is thus a synthesis of community ecology and population genetics that recognizes the interplay between changes in genetic composition and changes in species abundances in the evolution of interactions among species in communities.

The community genetics synthesis has many applications in natural and agricultural ecosystems. It is particularly valuable in situations where a community has undergone an extreme change that resulted in strong selection on its members. The need for such a synthesis might be best illustrated by a number of examples from our research efforts.

• The widespread use of genetically modified Bt corn for pest control can render its use quickly ineffective because it exerts intense selection towards resistance on the target organisms, the European corn borer (ECB). Resistance management of Bt corn requires a thorough understanding of gene flow among ECB demes in the spatial mosaic of Bt and non-Bt corn. In addition, the population and evolutionary dynamics of the European corn borer are affected by its predator, parasitoid and disease community.
• Prairie fragmentation changes both population dynamics and genetic composition of prairie plants by directly affecting pollination, in particular in small and isolated prairie patches.
• Extensive cultivation and expansion of crops, such as corn, can elicit an evolutionary response in their associated pathogens (e.g., corn smut). An increase in host abundance and a change in growing conditions can alter the competitive hierarchy of different pathogen strains, for instance, by favoring more virulent strains.
• Lakes are frequently stocked with game fish, and this increases predation pressure on plankton. This pressure can alter the phenotypic composition of plankton by favoring plankton that tolerate oxygen levels low enough so that they can persist at depths where they escape fish predation. This can cause a rapid change in the genotypic composition of the plankton community after introduction of fish.
• Global climate change can affect native plant communities by allowing invasions of plant species due to changes in plant fitness brought on by different climatic conditions. The invaders need not be exotic species. For instance, a species with a large home range could move northwards and thus promote crossing between individuals from previously distinct geographic ranges and this could result in outbreeding depression. This can change the competitive rank of this species in the community and thus affect community dynamics.
• Today's landscape is a mosaic of natural and agricultural ecosystems. Genes from agricultural crops can enter natural systems through cross-breeding between crops and closely related wild plants. This can affect fitness of wild plants and thus alter community dynamics by changing the competitive hierarchy of the plants composing the natural community.

The CCG unites expertise in insect, weed, parasite, and plant-disease management with expertise in basic mechanisms of ecology and evolution. Our research efforts have largely concerned evolution and management of terrestrial systems, such as crop-pest interactions or management of prairie fragments, but have also included aquatic systems, such as interactions between fish and plankton communities. Recent advances in molecular, population, and quantitative genetics have set the stage for a broadly synthetic approach to understanding evolution in a community context. Rather than viewing organisms as independent entities, we consider their evolutionary responses in the community context in which they occur.

References:

Antonovics, J. (1992) Toward Community Genetics. In Plant Resistance to Herbivores and Pathogens: Ecology, Evolution, and Genetics. R.S. Fritz and E.L. Simms (eds). University of Chicago Press, Chicago, IL.

Page last modified Wednesday, August 22, 2001