Jinan Lu1, Yaolin Guo1, Christina L. Richards2, Linfeng Li1, Jihua Wu3, Bo Li1,4, Rui-Ting Ju1
1 Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China.
2 Department of Integrative Biology, University of South Florida, Tampa, FL, USA.
3 State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China.
4 Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Centre for Invasion Biology, Institute of Biodiversity, Yunnan University, Kunming, China.
Abstract
Rapid adaptive evolution following introduction is key for invasive plants’ success. Previous studies have documented differences in traits between native- and introduced-range plants under specialist-enemy release but have rarely considered the adaptive covariation in multidimensional traits across a large geographic scale in the context of generalist-enemy attacks. Using a common garden experiment, we compared variation in multiple traits related to growth, fecundity and leaf quality affecting herbivore consumption among 90 genotypes of the widespread invasive plant Spartina alterniflora across latitudes in its native (~800 km) and introduced (~2000 km) ranges. We tested the leaf palatability of those genotypes to generalist insects (Laelia coenosa and Locusta migratoria). We employed complementary approaches, including syndrome clustering, selection analysis and testing for trait-climate relationships, to ascertain whether multiple-trait variation was adaptive. In 13 of 18 measured variables, we found genetic-based differences between plant ranges, with eight exhibiting latitudinal clines within the introduced range. The majority of introduced genotypes developed a novel ‘strong’ syndrome with large growth, high reproduction, low nutrition, and high defenses. Variation in most syndrome traits could enhance Spartina fitness and was associated with differences in temperature and/or precipitation between plant provenances. Our findings indicate that within only 40 years since its introduction to China, Spartina has undergone rapid adaptive evolution in multidimensional traits that promotes its invasiveness, partly explaining why this grass becomes the most successful invader along the country’s coast.
Keywords: biological invasion, evolution, generalist, latitudinal cline, plant syndrome, plant defense, plant introduction, Spartina alterniflora
Status: submitted
Fig. 1 Collection sites of Spartina alterniflora on the southeastern coast of the USA (a, native range) and the eastern coast of China (b, introduced range). The map projection used is Lambert.