Genetically Based Trait Differentiation but Lack of Trade-offs between Stress Tolerance and Performance in Introduced Canada Thistle

Abstract

Trade-offs between performance and tolerance of abiotic and biotic stress have been proposed to explain both the success of invasive species and frequently observed size differences between native and introduced populations. Canada thistle seeds collected from across the introduced North American and the native European range were grown in benign and stressful conditions (nutrient stress, shading, simulated herbivory, drought, and mowing), to evaluate whether native and introduced individuals differ in performance or stress tolerance. An additional experiment assessed the strength of maternal effects by comparing plants derived from field-collected seeds with those derived from clones grown in the glasshouse. Introduced populations tended to be larger in size, but no trade-off of stress tolerance with performance was detected; introduced populations had either superior performance or equivalent trait values and survivorship in the treatment common gardens. We also detected evidence of parallel latitudinal clines of some traits in both the native and introduced ranges and associations with climate variables in some treatments, consistent with recent climate adaptation within the introduced range. Our results are consistent with rapid adaptation of introduced populations, but, contrary to predictions, the evolution of invasive traits did not come at the cost of reduced stress tolerance.

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

“…We found that the climatic conditions at the collecting sites were significantly associated with resistance traits in both common gardens, but only for plants from the native range, whereas for plants from the introduced range there were only very few significant associations. Many previous studies of invasive plants have documented the development of parallel clinal patterns in ecological traits among populations of native and introduced ranges (Agrawal et al ., 2015; Leger & Rice, 2007; Etterson et al ., 2008; Rosche et al ., 2019; Hodgins et al ., 2020) and have usually interpreted this as evidence for rapid post-invasion evolution and adaptation. However, there are also studies of successful invasive plants with unparalleled (Bhattarai et al ., 2017; Yang et al ., 2021; Woods & Sultan, 2022) or no clinal patterns at all (Endriss et al ., 2018; Sun & Roderick, 2019), and our results also provide little evidence for post-invasion genetic differentiation of introduced European or North American populations in relation to climate.…”

A New Year's spotlight on two years of publication

“…(2020) assessed the impact of demographic processes on genomic diversity and positive selection in Arabidopsis lyrata by analyzing re-sequencing data from 52 populations collected worldwide. Vaidya and Stinchcombe (2020) used the Medicago truncatula - Ensifer meliloti system to demonstrate that genotype-by-environment interactions make a significant contribution to maintaining genetic variation in mutualisms, and Hodgins et al. (2020) found that invasive populations of Canada thistle show rapid adaptation with no trade-off between stress tolerance and performance.…”

Plant Evolutionary Adaptation

“…A widely held explanation for this pattern, as well as for the overall success of the invaders, is that invasive plants trade off tolerance to abiotic and biotic stresses for increased performance. In this issue, Hodgins et al. (2020) investigate this hypothesis in the noxious weed, Canada thistle ( Cirsium arvense ), which is native to Eurasia, but has invaded all other continents except Antarctica.…”