Hybridization and invasion: an experimental test with diffuse knapweed (Centaurea diffusa Lam.)

A number of studies have suggested a link between hybridization and invasion. In this study, we experimentally test the potential for hybridization to influence invasion through a greenhouse common garden study. Diffuse knapweed (Centaurea diffusa Lam.) was introduced to North America with admixture from spotted knapweed (Centaurea stoebe subsp. stoebe L.). Comparisons between North American diffuse knapweed (including hybrid phenotypes) and native (European) diffuse knapweed in a common garden did not reveal enhanced performance or increased phenotypic variance, suggesting that pre-introduction hybridization or, more generally, post-introduction evolutionary change, has not significantly contributed to the invasion of diffuse knapweed. In contrast, early generation hybrids [artificially created Back Cross 1 (BC1) plants] exhibited increased variance for eight of the examined traits, and greater leaf and reproductive shoot production when compared to North American diffuse knapweed. Ind...多项研究已证实杂交与生物入侵之间存在关联。本研究借助温室同质园试验（common garden study），通过实验手段验证了杂交可通过何种途径影响生物入侵过程。扩散矢车菊（Centaurea diffusa Lam.）被引入北美后，与斑点矢车菊（Centaurea stoebe subsp. stoebe L.）发生了基因混合。在同质园试验中，对北美扩散矢车菊（包含杂交表型个体）与本土（欧洲）扩散矢车菊进行对比分析，未发现前者的生长表现更优或表型变异更高，这表明引入前的杂交事件，或更宽泛意义上的引入后演化改变，并未显著推动扩散矢车菊的入侵进程。与之相反，人工构建的早期世代回交1代（Back Cross 1, BC1）杂交植株，在8个检测性状上均表现出变异程度提升，且相较于北美扩散矢车菊，其叶片与生殖枝的生成量更高。本研究初步结果表明……