One of the fundamental questions in ecology is why species occur in some areas and not in others. Range limits, the boundaries between a species’ presence and absence, reflect the interplay of dispersal and population dynamics driven by biotic and abiotic conditions. As a result, range limits may shift as dispersal barriers are removed, climates change, and local species composition is altered, but the relative importance of these mechanisms is still not well understood. This is particularly true for introduced species, where current range limits may or may not reflect range limits at equilibrium, and is becoming more pressing under the effects of global climate change. To understand the drivers and stability of range limits in introduced Rumex conglomeratus, we used common garden experiments growing plants within, at the edge of and beyond their current range edge. Seeds were sourced from both lowland and upland populations and planted at all three sites. By measuring survival, growth, and the occurrence of reproduction, we tested whether upland populations are locally adapted to high elevation sites and whether plants were capable of surviving and reproducing above the current range edge. However, we found that upland populations were not better adapted to higher elevations, and often were small and performed more poorly than lowland populations across sites. Upland populations appear to be maintained by human-aided seed dispersal from lowland populations, which may constrain the opportunity for local adaptation. Although some plants survived above the current range edge, frost and growing season length restricted plant size and reproduction was infrequent. Therefore, the current range limit seems unlikely to expand as long as regular frost continues at the range edge and dispersal from the lowland continues to prevent local adaptation to upland environments.

生态学的基本问题之一是为什么物种出现在某些地区而不是其他地区。范围限制，即物种存在和不存在之间的界限，反映了生物和非生物条件驱动的扩散和种群动态的相互作用。因此，随着扩散障碍的消除、气候变化和当地物种组成的改变，范围限制可能会发生变化，但这些机制的相对重要性仍不清楚。对于引进物种来说尤其如此，目前的范围限制可能反映也可能不反映平衡时的范围限制，并且在全球气候变化的影响下变得更加紧迫。了解引入的酸模的范围限制的驱动因素和稳定性，我们使用常见的花园实验在其当前范围边缘内、边缘和之外种植植物。种子来自低地和高地种群，并在所有三个地点种植。通过测量生存、生长和繁殖的发生，我们测试了高地种群是否局部适应高海拔地区，以及植物是否能够在当前范围边缘以上生存和繁殖。然而，我们发现高地种群并不能更好地适应更高的海拔，而且通常规模较小，而且各个地点的表现都比低地种群更差。高地种群似乎是通过人类辅助从低地种群传播种子来维持的，这可能会限制当地适应的机会。尽管一些植物在当前范围边缘以上存活下来，霜冻和生长季节的长度限制了植物的大小并且繁殖很少。因此，只要范围边缘定期霜冻持续存在，并且低地的扩散继续阻碍当地对高地环境的适应，目前的范围限制似乎就不太可能扩大。