Recent reviews in the field of community and ecosystem genetics provide strong evidence that plant genetic factors can have distinct community and ecosystem phenotypes, that these phenotypes can be heritable, and that the community phenotype can feed back to affect the fitness of the individual plant genotypes. Reviews to date have covered a range of conceptual topics including: i) the role of plant hybridization in maintaining associated biodiversity; ii) genes to ecosystems links; iii) the importance of functional genomics to community genetics; iv) the role of genetically based feedbacks in community genetics; and v) the effects of genotypic diversity on community and ecosystem-level properties.  Such a diverse array of topics clearly link genetic variation in plants to community and ecosystem processes, and provide compelling evidence for the importance of bridging community and ecosystem ecology with evolutionary biology.  These reviews are largely qualitative, providing conceptual frameworks for understanding how genetic variation in one species may affect community traits and ecosystem services with little comparative synthesis of the broader patterns in the strength of plant genetic effects within or across systems.  Using two genetic approaches and seven different plant systems, we present findings from a meta-analysis examining the strength of the effects of plant genetic introgression and genotypic diversity across individual, community and ecosystem levels with the goal of synthesizing the patterns to date.

Results/Conclusions

We found that:  1. The strength of plant genetic effects can be quite high, however the overall strength of genetic effects on most response variables declined as the level of organization increased.  2. Plant genetic effects varied such that introgression had a greater impact on individual phenotypes than extended effects on arthropods or microbes/fungi. In contrast, the greatest effects of genotypic diversity were on arthropods.  3. Plant genetic effects were greater on aboveground versus belowground processes, but there was no difference between terrestrial and aquatic environments.  4. The strength of the effects of intraspecific genotypic diversity tended to be weaker than interspecific genetic introgression.  5. Although genetic effects generally decline across levels of organization, in some cases they do not, suggesting that specific organisms and/or processes may respond more than others to underlying genetic variation.  Because patterns in the overall impacts of introgression and genotypic diversity were generally consistent across diverse study systems and consistent with theoretical expectations, these results provide generality for understanding the extended consequences of plant genetic variation across levels of organization, with evolutionary implications.