From genes to ecosystems: a synthesis of the effects of plant genetic factors across levels of organization

Abstract

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. We found that (i) the strength of plant genetic effects can be quite high; however, the overall strength of genetic effects on most response variables declined as the levels of organization increased. (ii) Plant genetic effects varied such that introgression had a greater impact on individual phenotypes than extended effects on arthropods or microbes/fungi. By contrast, the greatest effects of genotypic diversity were on arthropods. (iii) Plant genetic effects were greater on above-ground versus below-ground processes, but there was no difference between terrestrial and aquatic environments. (iv) The strength of the effects of intraspecific genotypic diversity tended to be weaker than interspecific genetic introgression. (v) 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.

Figure 1

Comparison of the effect size of (a) introgression and (b) genotypic diversity across levels of organization (i.e. on individual-, community- and ecosystem-level phenotypes). (a, b) When tests are characterized as individual-, community- or ecosystem-level phenotypes, there is a significant difference in the effect size of introgression. Bars represent mean effect size ±95% CI. Dashed line represents average effect size across all levels of organization.

Figure 2

Comparison of the effect size of (a) introgression and (b) genotypic diversity across taxa. (a) When tests are characterized as effects on plants, arthropods or soil and litter microbes and fungi, there are significant differences among groups in the effect size of introgression. Genetic introgression acts more strongly on the phenotypes of the plants themselves than on associated arthropods or microbes; however, the effect size is large regardless. Panel (b) shows a similar pattern, but stronger effects on arthropods than either individual phenotypes or microbes. Bars represent mean effect size±95% CI. Dashed line represents average effect size across all levels of organization.

Figure 3

Comparison of the effect size of (a, b) introgression and (b, d) genotypic diversity across diverse environments. (a) When tests are characterized as above or below-ground, the effects of introgression are stronger on above-ground traits and processes than below-ground. (b) When tests are characterized as terrestrial or aquatic, there is no difference in the effects of introgression in aquatic versus terrestrial environments. (c) Patterns are similar for genotypic diversity, where a significant difference is found in the effects of genotypic diversity on above- and below-ground traits and processes. (d) The effects of genotypic diversity are not different in terrestrial and aquatic systems. Bars represent mean effect size±95% CI. Dashed line represents average effect size across all levels of organization.