Community Genetics

by

Jennifer A. Schweitzer, Joseph K. Bailey

• LAST REVIEWED: 17 March 2021
• LAST MODIFIED: 27 March 2014
• DOI: 10.1093/obo/9780199830060-0069

Introduction

Community genetics is a relatively young empirical field that focuses upon the genetic relationships among species and how these interactions shape whole communities and ecosystem function. Species and individual genotypes continuously interact with other species and genotypes, as well as the environment, and the outcomes of these interactions are dictated, in part, by genes. These genetic interactions involve the direct expression of phenotypes that affect other species but do not require the reciprocity of coevolution among species. Much of this work, to date, has been undertaken with dominant plant species, due to their natural histories and complex interactions with other species, such as herbivores, symbionts, and pathogens that have both ecological and evolutionary consequences. There is much overlap in the study of community genetics, eco-evolutionary dynamics, and the geographic mosaic of coevolution, leading some authors to suggest that the term is unnecessary. However, since community genetics was first defined by Antonovics in 1992, it is clear that a term was necessary to describe genetically based interactions among species (i.e., the role of genotype or genetic variation in structuring associated communities and ecosystem processes). In contrast, eco-evo dynamics is the study of feedbacks among ecology and evolution and the geographic mosaic of coevolution is the study of species interactions across landscapes that can lead to “hot” and “cold” spots of coevolution. Therefore, while they differ in scale and scope, all three fields of study are similarly grounded in the theory of indirect genetic effects, whereby the genes of one individual or species impacts the fitness or performance of another individual or species. Empirical studies in community genetics across a range of habitat types and systems have demonstrated the roles of plant phenotype, genotype, genetic variation, genotypic variation, and phylogenetic variation in structuring plant-associated communities and ecosystem processes. Current empirical and theoretical research is focusing on understanding the importance of genetic scale, spatial scale, the role of environmental variation, genetic X genetic X environmental interactions, and genetic feedbacks among interacting species, as well as the application of community genetics approaches to applied questions. Research focused on the application of community genetics approaches may become especially important in the context of global change that is leading to novel genetic interactions among species, altering community composition and ecosystem function.

General Overviews

Since 1992, when the term community genetics was first defined, special features in Ecology in 2003 and Proceedings of the Royal Academy B in 2013 as well as multiple key reviews have been undertaken to organize, summarize, and synthesize community genetics studies and results (it should be noted that empirical studies are not keeping up with the reviews, leading to some redundancy across reviews). The special feature in Ecology in 2003 highlighted both “reductionist” and “holistic” approaches to the study of genetic interactions among species. These approaches were differentiated by either a classical population genetics approach tracing potentially rapid population changes in one population to another population (reductionist) or a “genes-to-ecosystem” approach (holistic), tracing heritable genetic variation in one species to affect associated communities and ecosystem processes. Eight additional papers highlighted the advantages, disadvantages, and opportunities afforded by taking a community genetics approach to understanding the ecology and evolution of interacting species. Expanded reviews of this approach with applications were undertaken in Whitham, et al. 2006 and from a genomics perspective in Whitham, et al. 2008. Johnson and Stinchcombe 2007 reviewed evidence of the importance of evolutionary biology to community ecology, while Hughes, et al. 2008 tackled a fundamental assumption of community genetics, namely, that genetic diversity within species is as important to ecological processes as among species variation. Bailey, et al. 2009 provided the first meta-analysis of the strength of plant genetic effects on individuals, communities, and ecosystems across plant systems. Recently, a Special Feature in the Philosophical Transactions of the Royal Society B summarized some of the current research on the topic by highlighting twelve research and review papers in a variety of systems and contexts linking community ecology and genetics.

• Bailey, Joseph K., Jennifer A. Schweitzer, Julia Koricheva, et al. 2009. Community and ecosystem consequences of gene flow and genotypic diversity across systems and environments: A meta-analysis. Philosophical Transactions of the Royal Society B 364:1607–1616.

  This review found that plant genetics had larger effects on aboveground processes than belowground, that few differences in effects occur between terrestrial vs. aquatic systems, and that genetic effects generally declined across levels of organization (with a few exceptions). This study represents the first quantitative review of community genetics concepts.

• Hughes, A. Randall, Brian D. Inouye, Marc T. J. Johnson, Nora Underwood, and Mark Velland. 2008. Ecological consequences of genetic diversity. Ecology Letters 11:609–623.

  DOI: 10.1111/j.1461-0248.2008.01179.x

  A review highlighting the relative importance of within-species genetic diversity as a component of biodiversity. Important clarification of terminology within community genetics studies, highlighting the need for a broader diversity of taxa, study approaches and scope of genetic variation in ecological studies.

• Johnson, Marc T. J., and John R. Stinchcombe. 2007. An emerging synthesis between community ecology and evolutionary biology. Trends in Ecology & Evolution 22:250–257.

  DOI: 10.1016/j.tree.2007.01.014

  A review highlighting examples of how linkages between community ecology and evolutionary biology can and do occur. The authors cite four key conditions that would support the linkage of these fields and they also highlighted that more work is required to determine when and how these interactions occur.

• Neuhauser, Claudia, David A. Andow, George E. Heimpel, Georgiana May, Ruth G. Shaw, and Stuart Wagenius. 2003. Community genetics: Expanding the synthesis of ecology and genetics. Ecology 84:545–558.

  DOI: 10.1890/0012-9658(2003)084[0545:CGETSO]2.0.CO;2

  Key highlighted paper in a special feature focusing on the application and importance of a community genetics approach. With an emphasis on applications, this paper uses four examples, with empirical and modeling data, to indicate the importance of both ecological and genetic viewpoints.

• Whitham, Thomas G., Joseph K. Bailey, Jennifer A. Schweitzer, et al. 2006. A framework for community and ecosystem genetics: From genes to ecosystems. Nature Reviews Genetics 7:510–523.

  DOI: 10.1038/nrg1877

  A key review expanding the examples and application of community and ecosystem genetics. The paper highlights both a “genes-to-ecosystem” perspective and a multidisciplinary approach to better understanding the extended consequences of species genetic interactions.

• Whitham, Thomas G., Stephen P. DiFazio, Jennifer A. Schweitzer, et al. 2008. Extending genomics to natural communities and ecosystems. Science 320:492–495.

  DOI: 10.1126/science.1153918

  Perspectives paper highlighting the role and mechanisms of genomics, with the growing list of species that have had their genomes sequenced, in both community assembly and ecosystem processes in natural systems.

• Whitham, Thomas G., William P. Young, Gregory D. Martinsen, et al. 2003. Community and ecosystem genetics: A consequence of the extended phenotype. Ecology 84:559–573.

  DOI: 10.1890/0012-9658(2003)084[0559:CAEGAC]2.0.CO;2

  Another of the key highlighted papers in a special feature focusing on community genetics. This paper illustrates, with a single well-studied system (Populus spp.), that heritable genetic variation has extended consequences for associated communities and ecosystem processes.