Biological invasions and the spatial ecology of genes

入侵物种是指被引入其自然范围以外的地区，随后扩散并主导当地栖息地的动植物。由于它们是对生物多样性的主要威胁，也会极大地降低农业生产力，每年花费数十亿美元对抗入侵者。然而，除非我们更好地了解是什么原因使一些引入的物种入侵，而另一些物种保持稳定，否则我们无法成功地击退入侵者。考虑到这个目标，我集中在常见的芦苇(芦苇)上。一种以在北美和欧洲等世界各地的淡水水域形成的芦苇而闻名的物种。在这两个大陆，本土芦苇种群几千年来一直保持稳定，但一个多世纪前当一种欧洲芦苇品种引入北美时，这一切在北美都发生了变化。这种芦苇品种现在在北美入侵，那里的种群正在迅速扩散，并占领了河口、湖泊、池塘、溪流、以及其他以前是各种物种栖息地的栖息地。入侵芦苇现在是一个如此严重的问题，以至于它们被确定为加拿大自然栖息地中最具破坏性的植物之一。我的目标是找出为什么在原生范围内保持稳定的芦苇种群在转移到新的地区时会变得入侵和破坏。我将通过对入侵和稳定芦苇种群的生态进行详细分析来做到这一点。特别要注意这种入侵品系是否能耐受北美比其原生欧洲更广泛的栖息地。然后，我将调查入侵芦苇在北美各地的移动是否伴随着种群内的基因变化，使芦苇能够更好地适应他们的新环境。这种对芦苇原生和入侵栖息地的直接比较，结合对适应基因的搜索，将有助于我们更好地了解入侵行为，从而瞄准未来的潜在入侵者。

Invasive species are plants and animals that are introduced to regions outside their natural range, and subsequently spread out and dominate native habitats.  Because they are a major threat to biodiversity, and can also greatly reduce agricultural productivity, billions of dollars are spent each year fighting invaders.  However, we cannot successfully repel invaders until we have a better understanding of just what makes some introduced species invasive while others remain stable.  With this goal in mind, I am concentrating on the common reed (Phragmites australis), a species that is well known for the reed beds that it forms in freshwater sites round the world including North America and Europe.  In both continents, native reed populations have been stable for thousands of years, but this all changed in North America more than a century ago when a European strain of the common reed was introduced.  This strain is now invasive in North America, where populations are spreading rapidly and taking over estuaries, lakes, ponds, streams, and other habitats that were previously home to a wide range of species.  Invasive reeds are now such a problem that they have been identified as one of the most destructive plants in Canadian natural habitats.  I aim to find out just why it is that reed populations that remain stable in their native range become invasive and destructive when they move to new regions.  I will do this through a detailed analysis of the ecology of both invasive and stable reed populations, paying particular attention to whether the invasive strain can tolerate a much broader range of habitats in North America compared to its native Europe.  I will then investigate whether movement of invasive reeds across North America has been accompanied by genetic changes within populations that allow reeds to become better adapted to their new environments.  This direct comparison of reeds in their native and invaded habitats, combined with a search for adaptive genes, will help us to better understand invasions and therefore target future potential invaders.