Department of Plant Biology, University of Vermont Burlington, Vermont, 05405.
Appalachian Laboratory, University of Maryland Center for Environmental Science Frostburg, Maryland, 21532.
Ecol Evol. 2014 Apr;4(7):899-910. doi: 10.1002/ece3.966. Epub 2014 Feb 23.
Biological invasions can transform our understanding of how the interplay of historical isolation and contemporary (human-aided) dispersal affects the structure of intraspecific diversity in functional traits, and in turn, how changes in functional traits affect other scales of biological organization such as communities and ecosystems. Because biological invasions frequently involve the admixture of previously isolated lineages as a result of human-aided dispersal, studies of invasive populations can reveal how admixture results in novel genotypes and shifts in functional trait variation within populations. Further, because invasive species can be ecosystem engineers within invaded ecosystems, admixture-induced shifts in the functional traits of invaders can affect the composition of native biodiversity and alter the flow of resources through the system. Thus, invasions represent promising yet under-investigated examples of how the effects of short-term evolutionary changes can cascade across biological scales of diversity. Here, we propose a conceptual framework that admixture between divergent source populations during biological invasions can reorganize the genetic variation underlying key functional traits, leading to shifts in the mean and variance of functional traits within invasive populations. Changes in the mean or variance of key traits can initiate new ecological feedback mechanisms that result in a critical transition from a native ecosystem to a novel invasive ecosystem. We illustrate the application of this framework with reference to a well-studied plant model system in invasion biology and show how a combination of quantitative genetic experiments, functional trait studies, whole ecosystem field studies and modeling can be used to explore the dynamics predicted to trigger these critical transitions.
生物入侵可以改变我们对于历史隔离和当代（人为辅助）扩散相互作用如何影响功能性状种内多样性结构的理解，进而影响功能性状变化如何影响生物组织的其他尺度，如群落和生态系统。由于生物入侵通常涉及由于人为辅助扩散而导致的先前隔离谱系的混合，因此对入侵种群的研究可以揭示混合如何导致新的基因型和种群内功能性状变异的转变。此外，由于入侵物种可以成为入侵生态系统中的生态工程师，因此入侵物种功能性状的混合诱导变化会影响本地生物多样性的组成，并改变系统中资源的流动。因此，入侵代表了一个有前景但研究不足的例子，说明了短期进化变化的影响如何在生物多样性的多个尺度上级联。在这里，我们提出了一个概念框架，即在生物入侵过程中，不同来源种群之间的混合可以重新组织关键功能性状的遗传变异，导致入侵种群中功能性状的均值和方差发生变化。关键性状均值或方差的变化可以引发新的生态反馈机制，导致从本地生态系统向新的入侵生态系统的关键转变。我们通过参考入侵生物学中一个研究良好的植物模型系统来说明该框架的应用，并展示如何结合定量遗传实验、功能性状研究、整个生态系统实地研究和建模来探索预测引发这些关键转变的动态。
