Admixture and hybridization in North American cattails (Typha spp.)

每年，世界各地都有成百上千的物种被偶然或故意地迁移。 大多数物种无法在它们被引入的新环境中生存。 然而，由于不太清楚的原因，一些引进的物种表现得非常好，成为入侵物种，主宰新的栖息地，使本地物种灭绝，并花费数百万美元的根除计划。导致生物入侵的引入并不一定涉及特定地理区域的新物种：入侵也可能是由于引入本地物种的新遗传品种。 如果一个物种的种群在地理上分开的地区自然出现，例如加拿大的海洋省份和不列颠哥伦比亚省，就会发生这种情况。 在这个例子中，加拿大东部和西部的一个单一物种的种群已经彼此隔离了数千年，在此期间，它们进化成具有不同遗传谱系的东部和西部品种，尽管它们仍然被认为是单一物种的成员。 如果来自不列颠哥伦比亚省的个体找到了通往海洋省份的道路，它们可能会入侵新的栖息地。

Every year hundreds - possibly thousands - of species are either accidentally or intentionally moved around the world. Most species are unable to survive in the new environments to which they are introduced. However, for reasons that are not well understood, a few introduced species fare extraordinarily well and become invasive species that dominate new habitats, drive native species to extinction, and cost millions of dollars in eradication programs. Introductions that lead to biological invasions do not have to involve species that are new to a particular geographical area: invasions can also result from the introduction of new genetic varieties of a native species. This can happen if populations from a single species naturally occur in geographically separated areas, such as the Canadian maritime provinces and British Columbia. In this example, the eastern and western Canadian populations of a single species have been isolated from one another for thousands of years, during which time they evolved into eastern and western varieties with distinct genetic lineages, even though they are still considered members of a single species. If individuals from British Columia find their way to the maritime provinces, they could potentially become invasive in their new habitat.