Xinmin Lu1,2, Minyan He2, Saichun Tang3, Yuqing Wu4, Xu Shao2, Hui Wei2,5, Evan Siemann6, Jianqing Ding1,7. 1. College of Plant Sciences & Technology, Huazhong Agricultural University, Wuhan, Hubei, China. 2. Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei, China. 3. Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guangxi Institute of Botany, Chinese Academy of Sciences, Guilin, Guangxi, China. 4. Institute of Plant Protection, Henan Academy of Agriculture Sciences, Zhengzhou, Henan, China. 5. Pearl River Fisheries Research Institute, Guangzhou, Guangdong, China. 6. Biosciences Department, Rice University, Houston, TX, USA. 7. School of Life Sciences, Henan University, Kaifeng, Henan, China.
Abstract
BACKGROUND AND AIMS: The strengths of biotic interactions such as herbivory are expected to decrease with increasing latitude for native species. To what extent this applies to invasive species and what the consequences of this variation are for competition among native and invasive species remain unexplored. Here, herbivore impacts on the invasive plant Alternanthera philoxeroides and its competition with the native congener A. sessilis were estimated across latitudes in China. METHODS: An common garden experiment spanning ten latitudinal degrees was conducted to test how herbivore impacts on A. philoxeroides and A. sessilis, and competition between them change with latitude. In addition, a field survey was conducted from 21°N to 36.8°N to test whether A. philoxeroides invasiveness changes with latitude in nature as a result of variations in herbivory. KEY RESULTS: In the experiment, A. sessilis cover was significantly higher than A. philoxeroides cover when they competed in the absence of herbivores, but otherwise their cover was comparable at low latitude. However, A. philoxeroides cover was always higher on average than A. sessilis cover at middle latitude. At high latitude, only A. sessilis emerged in the second year. Herbivore abundance decreased with latitude and A. philoxeroides emerged earlier than A. sessilis at middle latitude. In the field survey, the ratio of A. philoxeroides to A. sessilis cover was hump shaped with latitude. CONCLUSION: These results indicate that herbivory may promote A. philoxeroides invasion only at low latitude by altering the outcome of competition in favour of the invader and point to the importance of other factors, such as earlier emergence, in A. philoxeroides invasion at higher latitudes. These results suggest that the key factors promoting plant invasions might change with latitude, highlighting the importance of teasing apart the roles of multiple factors in plant invasions within a biogeographic framework.
BACKGROUND AND AIMS: The strengths of biotic interactions such as herbivory are expected to decrease with increasing latitude for native species. To what extent this applies to invasive species and what the consequences of this variation are for competition among native and invasive species remain unexplored. Here, herbivore impacts on the invasive plant Alternanthera philoxeroides and its competition with the native congener A. sessilis were estimated across latitudes in China. METHODS: An common garden experiment spanning ten latitudinal degrees was conducted to test how herbivore impacts on A. philoxeroides and A. sessilis, and competition between them change with latitude. In addition, a field survey was conducted from 21°N to 36.8°N to test whether A. philoxeroides invasiveness changes with latitude in nature as a result of variations in herbivory. KEY RESULTS: In the experiment, A. sessilis cover was significantly higher than A. philoxeroides cover when they competed in the absence of herbivores, but otherwise their cover was comparable at low latitude. However, A. philoxeroides cover was always higher on average than A. sessilis cover at middle latitude. At high latitude, only A. sessilis emerged in the second year. Herbivore abundance decreased with latitude and A. philoxeroides emerged earlier than A. sessilis at middle latitude. In the field survey, the ratio of A. philoxeroides to A. sessilis cover was hump shaped with latitude. CONCLUSION: These results indicate that herbivory may promote A. philoxeroides invasion only at low latitude by altering the outcome of competition in favour of the invader and point to the importance of other factors, such as earlier emergence, in A. philoxeroides invasion at higher latitudes. These results suggest that the key factors promoting plant invasions might change with latitude, highlighting the importance of teasing apart the roles of multiple factors in plant invasions within a biogeographic framework.
Authors: Elizabeth T Borer; Eric W Seabloom; Daniel S Gruner; W Stanley Harpole; Helmut Hillebrand; Eric M Lind; Peter B Adler; Juan Alberti; T Michael Anderson; Jonathan D Bakker; Lori Biederman; Dana Blumenthal; Cynthia S Brown; Lars A Brudvig; Yvonne M Buckley; Marc Cadotte; Chengjin Chu; Elsa E Cleland; Michael J Crawley; Pedro Daleo; Ellen I Damschen; Kendi F Davies; Nicole M DeCrappeo; Guozhen Du; Jennifer Firn; Yann Hautier; Robert W Heckman; Andy Hector; Janneke HilleRisLambers; Oscar Iribarne; Julia A Klein; Johannes M H Knops; Kimberly J La Pierre; Andrew D B Leakey; Wei Li; Andrew S MacDougall; Rebecca L McCulley; Brett A Melbourne; Charles E Mitchell; Joslin L Moore; Brent Mortensen; Lydia R O'Halloran; John L Orrock; Jesús Pascual; Suzanne M Prober; David A Pyke; Anita C Risch; Martin Schuetz; Melinda D Smith; Carly J Stevens; Lauren L Sullivan; Ryan J Williams; Peter D Wragg; Justin P Wright; Louie H Yang Journal: Nature Date: 2014-03-09 Impact factor: 49.962