Identity recognition and the invasion of exotic plant.
Identity recognition (competition or altruism depending on genetic relationship) in plants was reported more infrequently than in animals. Few studies found identity recognition can help reducing competition between kin plants, and increasing population fitness. The exotic invasive plants usually form dense monoculture distribution, but native plants rarely distribute similarly. It might due to the invader had higher identity recognition ability, which could reduce intraspecific competition and enhance overall population fitness. In this study, we compared identity recognition ability between invasive Eupatorium adenophorum and two native congeners (Eupatorium fortunei and Eupatorium lindleyanum) in different nutrient condition and planting density. The results indicated that all three species did not show identity recognition ability in low and intermediate density condition. However, in high density condition, invasive E. adenophorum shew higher identity recognition ability than two native congeners. Recognition could alleviate intraspecific competition of invasive E. adenophorum through reducing carbon accumulation and RMF, but increasing the height to enhance light use efficiency. This strategy might contribute to high population fitness of E. adenophorum when it grew in high densities. This is the first study to explore the relationship between identity recognition and exotic plant invasion.