A footprint of tree‐genetics on the biota of the forest floor

Abstract

Understanding how far the effects of genes extend beyond the phenotype of an individual or population, is fundamental to the developing field of community genetics. We therefore assessed two geographically and genetically distinct populations of the Australian forest tree, Eucalyptus globulus, and the existence of genetic effects on a leaf litter invertebrate community and soil characteristics within a 15 year old common garden. Twenty trees per population were randomly selected for felling and placement of the apical branch next to the stump. This produced a leaf litter habitat of known genotype. Pitfall trap sampling for invertebrates, and linseed bioassay analyses of soil, were conducted within this habitat. Two key findings emerged. Firstly, assessment of 27 invertebrate orders (57 924 individuals) revealed significant population-level variation in leaf litter biodiversity (i.e. in community richness, abundance, composition and beta diversity). Secondly, considerable population-level differences in soil characteristics were evident based on linseed germination and growth responses. While recent findings in E. globulus have demonstrated consequences of genetic variation within forest trees for organisms that interact directly (i.e. proximally) with the living tree, these findings highlight the distal impacts that intraspecific genetic variation may have on communities and ecosystems. Such community genetic considerations have important implications for in situ community conservation, biodiversity management within restoration and plantation forestry, and our understanding of community-level evolutionary interactions involving foundation species.

Plant genotype and nitrogen loading influence seagrass productivity, biochemistry, and plant–herbivore interactions

“…Seagrass ecosystems sustain important detritus-based food webs (Fenchel 1977) and are also a major global carbon sink through the accumulation of a refractory detrital pool Cebrian 1996, Mateo et al 2007). Genotype identity strongly influences riparian and terrestrial litter-based arthropod communities associated with clonal plants (e.g., LeRoy et al 2006, Barbour et al 2009) and, ultimately, decomposition rates and nutrient remineralization (e.g., Schweitzer et al 2004, Crutsinger et al 2009) by determining the quantity and quality of litter produced. We found strong differences in detritus production among genotypes in Zostera marina, with the green genotype producing the most of a high quality (low C:N and low phenol) material, which could have large effects on the ecosystems dependent on eelgrass detritus.…”

Forest gene diversity is correlated with the composition and function of soil microbial communities

“…Swaty et al (2004) showed that, along a droughtstress gradient, mycorrhiza exhibited a unimodal pattern in which colonization was highest at intermediate stress/productivity levels; however, on the same trees, Stone et al (2010) showed that arthropods decreased linearly. Studies examining the role of plant genetic variation on above-and belowground communities have found that soil communities can sometimes display more idiosyncratic patterns than aboveground communities (Crutsinger et al 2008;Barbour et al 2009b); for example, Crutsinger et al (2008) found that litter-based microarthropod communities show weak effects of plant genotype and genotypic diversity compared with foliar herbivores (and other guilds) that show strong responses to genotype (Crutsinger et al 2006). In contrast, litter arthropods (at early stages of decay) and canopy arthropods are both affected by tree provenance-level genetic divergence within Eucalyptus globulus (Barbour et al 2009b).…”

Plant genotype influences aquatic‐terrestrial ecosystem linkages through timing and composition of insect emergence

“…) of plant genes on litter communities are much less understood, though specific litter taxa have been shown to respond to intraspecific plant variation (Barbour et al. , Wojtowicz et al. ).…”

“…The genetic similarity hypothesis predicts that plants with more similar genotypes will support more similar traits (e.g., phytochemistry), which in turn are associated with more similar arthropod communities (sensu Bangert et al 2006b). The afterlife effects (sensu Findlay et al 1996) of plant genes on litter communities are much less understood, though specific litter taxa have been shown to respond to intraspecific plant variation (Barbour et al 2009a, Wojtowicz et al 2014. Variation within tree species can also influence litter decomposition and invertebrate communities in terrestrial (Schweitzer et al 2005) and aquatic (LeRoy et al 2006, Lecerf and Chauvet 2008, Jackrel and Wootton 2014 ecosystems.…”