Department of Ecology and Evolutionary Biology, University of Tennessee-Knoxville, Knoxville, Tennessee, United States of America.
PLoS One. 2013;8(1):e53718. doi: 10.1371/journal.pone.0053718. Epub 2013 Jan 17.
Aboveground-belowground linkages are recognized as divers of community dynamics and ecosystem processes, but the impacts of plant-neighbor interactions on these linkages are virtually unknown. Plant-neighbor interactions are a type of interspecific indirect genetic effect (IIGE) if the focal plant's phenotype is altered by the expression of genes in a neighboring heterospecific plant, and IIGEs could persist after plant senescence to affect ecosystem processes. This perspective can provide insight into how plant-neighbor interactions affect evolution, as IIGEs are capable of altering species interactions and community composition over time. Utilizing genotypes of Solidago altissima and Solidago gigantea, we experimentally tested whether IIGEs that had affected living focal plants would affect litter decomposition rate, as well as nitrogen (N) and phosphorous (P) dynamics after the focal plant senesced. We found that species interactions affected N release and genotype interactions affected P immobilization. From a previous study we knew that neighbor genotype influenced patterns of biomass allocation for focal plants. Here we extend those previous results to show that these changes in biomass allocation altered litter quality, that then altered rates of decomposition and nutrient cycling. Our results provide insights into above- and belowground linkages by showing that, through their effects on plant litter quality (e.g., litter lignin:N), IIGEs can have afterlife effects, tying plant-neighbor interactions to ecosystem processes. This holistic approach advances our understanding of decomposition and nutrient cycling by showing that evolutionary processes (i.e., IIGEs) can influence ecosystem functioning after plant senescence. Because plant traits are determined by the combined effects of genetic and environmental influences, and because these traits are known to affect decomposition and nutrient cycling, we suggest that ecosystem processes can be described as gene-less products of genetic interactions among the species comprising ecological communities.
地上-地下联系被认为是群落动态和生态系统过程的多样化因素，但植物-邻居相互作用对这些联系的影响实际上是未知的。如果焦点植物的表型因相邻异质植物中基因的表达而改变，则植物-邻居相互作用是一种种间间接遗传效应 (IIGE)，并且 IIGE 可以在植物衰老后持续存在，从而影响生态系统过程。这种观点可以深入了解植物-邻居相互作用如何影响进化，因为 IIGE 能够随着时间的推移改变物种相互作用和群落组成。利用 Solidago altissima 和 Solidago gigantea 的基因型，我们通过实验测试了是否影响活体焦点植物的 IIGE 会影响凋落物分解率，以及焦点植物衰老后氮 (N) 和磷 (P) 的动态。我们发现，种间相互作用影响 N 释放，基因型相互作用影响 P 固定。从之前的一项研究中我们知道，邻居基因型会影响焦点植物的生物量分配模式。在这里，我们扩展了之前的结果，表明这些生物量分配的变化改变了凋落物质量，从而改变了分解和养分循环的速率。我们的结果通过显示 IIGE 通过影响植物凋落物质量（例如凋落物木质素：N）对地上和地下联系有后续影响，将植物-邻居相互作用与生态系统过程联系起来，提供了对这些联系的深入了解。这种整体方法通过显示进化过程（即 IIGE）可以在植物衰老后影响生态系统功能，推进了我们对分解和养分循环的理解。由于植物性状是由遗传和环境影响的综合作用决定的，并且已知这些性状会影响分解和养分循环，因此我们建议生态系统过程可以被描述为由构成生态群落的物种之间遗传相互作用产生的无基因产物。
