Print PageCommunity genetics has focused on the community- and ecosystem-level consequences of intraspecific genetic variation. To date, it is well established that genetic variation within host-plant species can have strong effects on particular trophic levels, such as leaf herbivores. Recent work has sought to elucidate the specific plant traits that underlie these genetic effects, as well as to understand how the effects of trait variation extend across multiple trophic groups. We studied the above- and belowground communities associated with a dominant dioecious shrub, Baccharis pilularis, which occurs as two distinct architectural forms (upright and prostrate) in the coastal dunes of California. Using a common garden experiment, we asked how genetic variation in plant architecture influences the diversity and structure of soil bacteria, fungi, litter microarthropods, and foliage arthropods.
Results/Conclusions
We found that both above- and belowground communities varied considerably in their diversity and composition between plant architectural morphs. Plant trait mechanisms that accounted for these patterns appeared to operate primarily through differences in microenvironment. Thus, microbes and arthropods responded more strongly to abiotic factors, such as wind buffering caused by plant architecture, and less to biotic factors, such as variation in foliage or litter quality. While previous studies have shown a dampening of plant genetic effects belowground, our results show similar effect sizes between these distinct subcommunities. Our results suggest that a more complete understanding of the ecological consequences of plant genetic variation requires comparisons of above- and belowground interactions within terrestrial ecosystems, as well as more explicit linkage between intraspecific variation in plant functional traits to community responses.
