Disparate eVects of plant genotypic diversity on foliage and litter arthropod communities

IntraspeciWc diversity can inXuence the structure of associated communities, though whether litter-based and foliage-based arthropod communities respond to intraspeciWc diversity in similar ways remains unclear. In this study, we compared the eVects of host-plant genotype and genotypic diversity of the perennial plant, Solidago altissima, on the arthropod community associated with living plant tissue (foliage-based community) and microarthropods associated with leaf litter (litter-based community). We found that variation among host-plant genotypes had strong eVects on the diversity and composition of foliagebased arthropods, but only weak eVects on litter-based microarthropods. Furthermore, host-plant genotypic diversity was positively related to the abundance and diversity of foliage-based arthropods, and within the herbivore and predator trophic levels. In contrast, there were minimal eVects of plant genotypic diversity on litter-based microarthropods in any trophic level. Our study illustrates that incorporating communities associated with living foliage and senesced litter into studies of community genetics can lead to very diVerent conclusions about the importance of intraspeciWc diversity than when only foliage-based community responses are considered in isolation.