Cross-continental variation of herbivore resistance in a global plant invader

While successful plant invasions often occur in novel environments, invasive species usually occupy broad niches within their native and introduced ranges. A better understanding of the process of invasion therefore requires a wide sampling of ranges, and a good knowledge of introduction history. We tested for differentiation in herbivore resistance among 128 introduced (European, North American) and native (Chinese, Japanese) populations of the invasive Japanese knotweed (Reynoutria japonica) in two common gardens in the native range: one in Shanghai and the other in Yunnan. In both common gardens, we found that herbivore resistance of plants from introduced populations differed from that from native populations in China but not from native populations in Japan, the putative source of introduction. Compared to native Chinese populations, plants from native Japanese populations and introduced European and North American populations had thicker leaves in both common gardens, and a lower ..., In the middle of the growing season, we estimated herbivore damage—separately for beetle and caterpillar damage—as the percentage of leaf area eaten on each plant. Two days later, we sampled five fresh, fully developed leaves (the 1st, 2nd, 4th, 5th, and 6th leaves from the top) from the tallest shoot of each plant and measured the thickness of each leaf with a digital micrometer (Digimatic Outside Micrometer, Mitutoyo, Japan) in both gardens, and its toughness with a penetrometer (FA10, SAUTER, Balingen, Germany) in the Shanghai garden and with a mechanical testing machine (ZQ990A, Dongguan Zhiqu Precision Instrument Co., Ltd, China) in the Xishuangbanna garden. We then estimated the leaf thickness and toughness for each plant as the averages of the five measurements. We measured all plant traits in the Xishuangbanna and Shanghai common gardens from July 14 to 21, 2022, and July 24 to 31, 2022, respectively.
Finally, we dried all leaves at 60 °C for 72 h to analyze for leaf chemistry. ..., , # Cross-continental variation of herbivore resistance in a global plant invader
[https://doi.org/10.5061/dryad.qbzkh18r4](https://doi.org/10.5061/dryad.qbzkh18r4)

Contact Peipei Cao ([[e-mail]](mailto:[e-mail])) with any questions. This manuscript has been accepted for publication (29-Jan-2025):

Cao, P.P., Z.Y. Liao, S.Y. Wang, M. Parepa, L. Zhang, J.W. Bi, Y.J. Zhao, Y.L. Guo, T.T. Lin, S.B. Endriss, J.H. Wu, R.T. Ju, C.L. Richards, O. Bossdorf and B. Li. Cross-continental variation of herbivore resistance in a global plant invader. Ecography (accepted). 10.1111/ecog.07569

## Data files include:

### herb-trait.csv

This file contains data on leaf traits and phytochemistry. All data were collected by the authors.

| variables | units | description |
| :---------------- | :--------------------- | :-------------------------------------------------------------------------- |
| Gar...