Rowe Courtney L J, Leger Elizabeth A
USDA Forest Service, Plumas National Forest Quincy, CA, USA.
Department of Natural Resources and Environmental Science, University of Nevada Reno, NV, USA.
Evol Appl. 2011 May;4(3):485-98. doi: 10.1111/j.1752-4571.2010.00162.x. Epub 2010 Oct 29.
Widespread invasion by Bromus tectorum (cheatgrass) in the Intermountain West has drastically altered native plant communities. We investigated whether Elymus multisetus (big squirreltail) is evolving in response to invasion and what traits contribute to increased performance. Seedlings from invaded areas exhibited significantly greater tolerance to B. tectorum competition and a greater ability to suppress B. tectorum biomass than seedlings from adjacent uninvaded areas. To identify potentially adaptive traits, we examined which phenological and phenotypic traits were correlated with seedling performance within the uninvaded area, determined their genetic variation by measuring sibling resemblance, and asked whether trait distribution had shifted in invaded areas. Increased tolerance to competition was correlated with early seedling root to shoot ratio, root fork number, and fine root length. Root forks differed among families, but none of these traits differed significantly across invasion status. Additionally, we surveyed more broadly for traits that varied between invaded and uninvaded areas. Elymus multisetus plants collected from invaded areas were smaller, allocated more biomass to roots, and produced a higher percentage of fine roots than plants from uninvaded areas. The ability of native populations to evolve in response to invasion has significant implications for the management and restoration of B. tectorum-invaded communities.
雀麦（ cheatgrass）在山间西部的广泛入侵极大地改变了当地的植物群落。我们研究了多花披碱草（big squirreltail）是否正在因入侵而发生进化，以及哪些性状有助于提高其性能。来自入侵地区的幼苗对雀麦竞争的耐受性明显更强，且比来自相邻未入侵地区的幼苗具有更强的抑制雀麦生物量的能力。为了确定潜在的适应性性状，我们研究了哪些物候和表型性状与未入侵地区内的幼苗性能相关，通过测量同胞相似性来确定它们的遗传变异，并询问性状分布在入侵地区是否发生了变化。对竞争的耐受性增强与幼苗早期的根冠比、根叉数和细根长度相关。根叉在不同家族间存在差异，但这些性状在不同入侵状态下均无显著差异。此外，我们更广泛地调查了入侵和未入侵地区之间存在差异的性状。从入侵地区采集的多花披碱草植株比未入侵地区的植株更小，将更多生物量分配到根部，且细根比例更高。本地种群因入侵而进化的能力对雀麦入侵群落的管理和恢复具有重要意义。
