title: Integrating novel chemical weapons and evolutionarily increased competitive ability in success of a tropical invader.
abstract: The evolution of increased competitive ability (EICA) hypothesis and the novel weapons hypothesis (NWH) are two non-mutually exclusive mechanisms for exotic plant invasions, but few studies have simultaneously tested these hypotheses. Here we aimed to integrate them in the context of Chromolaena odorata invasion. We conducted two common garden experiments in order to test the EICA hypothesis, and two laboratory experiments in order to test the NWH. In common conditions, C. odorata plants from the nonnative range were better competitors but not larger than plants from the native range, either with or without the experimental manipulation of consumers. Chromolaena odorata plants from the nonnative range were more poorly defended against aboveground herbivores but better defended against soil-borne enemies. Chromolaena odorata plants from the nonnative range produced more odoratin (Eupatorium) (a unique compound of C. odorata with both allelopathic and defensive activities) and elicited stronger allelopathic effects on species native to China, the nonnative range of the invader, than on natives of Mexico, the native range of the invader. Our results suggest that invasive plants may evolve increased competitive ability after being introduced by increasing the production of novel allelochemicals, potentially in response to naïve competitors and new enemy regimes.
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan Province, 650223, China.
authors.forename: Yu-Long
authors.initials: YL
authors.lastname: Zheng
authors.affiliation: College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, Liaoning Province, 110866, China.
authors.forename: Yu-Long
authors.initials: YL
authors.lastname: Feng
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan Province, 650223, China.
authors.forename: Li-Kun
authors.initials: LK
authors.lastname: Zhang
authors.affiliation: Division of Biological Sciences and the Institute on Ecosystems, The University of Montana, Missoula, MT, 59812, USA.
authors.forename: Ragan M
authors.initials: RM
authors.lastname: Callaway
authors.affiliation: Departamento de Ecologôa de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autônoma de Mexico, Apartado Postal 70-275, CP 04510, México DF, Mexico.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Valiente-Banuet
authors.affiliation: College of Life Sciences, Hebei University, Baoding, Hebei Province, 071002, China.
authors.forename: Du-Qiang
authors.initials: DQ
authors.lastname: Luo
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan Province, 650223, China.
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Liao
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan Province, 650223, China.
authors.forename: Yan-Bao
authors.initials: YB
authors.lastname: Lei
authors.affiliation: Department of Life Sciences, University of the West Indies, St Augustine, Trinidad and Tobago.
authors.forename: Gregor F
authors.initials: GF
authors.lastname: Barclay
authors.affiliation: Departamento de Ecologôa de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autônoma de Mexico, Apartado Postal 70-275, CP 04510, México DF, Mexico.
authors.forename: Carlos
authors.initials: C
authors.lastname: Silva-Pereyra
mesh_terms: D064089:Allelopathy; D005075:Biological Evolution; D018533:Biomass; D036604:Chromolaena / Q000254:growth & development / Q000502:physiology*; D005843:Geography; D058865:Introduced Species; D008954:Models, Biological; D012717:Sesquiterpenes / Q000032:analysis / Q000737:chemistry; D014329:Tropical Climate
chemical_list: D012717:Sesquiterpenes; C018119:odoratin
keywords: Chromolaena odorata; aboveground and soil-borne enemies; allelochemicals; enemy suppression; evolution of increased competitive ability (EICA); intraspecific competition; invasion; novel weapons hypothesis