Mechanisms to understand the basis of species invasiveness

生物入侵是全球生物多样性变化的主要来源。了解在建立-传播阶段和影响阶段促成入侵成功的因素对于减少与非本地物种引入相关的生态、经济和健康问题至关重要。先前的研究已经确定，一些引入并在新的生态系统中建立的NIS将比在相同营养水平的互补本地物种产生更大的生态影响，这可能是由于猎物的幼稚。尽管最近的工作集中在功能性反应的差异上，即动物相对于食物密度的摄食率，但事实证明，要发展出预测NIS影响的概论是非常具有挑战性的。这项工作表明，入侵性（即高影响）NIS的摄食率通常高于其原生类似物。然而，这些摄食率差异的潜在基础尚未得到解决，也没有在不同分类类群之间的模式的普遍性。

Biological invasions are a leading source of biodiversity change globally. Understanding the factors that contribute to invasion success at both the establishment-spread stage and impact stage are vital to reducing ecological, economic and health problems associated with introduction of nonindigenous species (NIS). Prior work has determined that some NIS that are introduced to and establish in a new ecosystem will have a greater ecological impact than do complementary native species at the same trophic level, possibly owing to prey naivety. It has proven very challenging to develop generalities to predict NIS impact, though recent work has focused on differences in functional responses - the feeding rate of an animal relative to food density. This work revealed generally higher feeding rates by invasive (i.e. high impact) NIS than their native analogues. However, the underlying basis for these feeding rate differences has not been addressed, nor has the generality of the pattern across different taxonomic groups. In this proposal I will conduct comparative feeding trials of NIS and native species from a broad array of environments - including terrestrial and aquatic environments - and trophic levels - predators versus herbivores - to test for differences in functional responses. Taxa selected will include broadly different taxonomic groups including beetles, mussels, fishes, ascidians and crabs, allowing us to examine the generality of feeding rate differences. Feeding trials of beetles will be videotaped, which will allow us to determine the species' behavioural repertoires (e.g. time budgets, attack rate). Functional responses are expressed through the interaction of an organism’s physiology with its environment. When active, genes produce mRNAs, and up-regulation or down-regulation of these genes produces more or fewer of these molecules. Translation of these molecules into proteins enacts the responses (ie. feeding rate). We will apply transcriptomics using a candidate gene approach, whereby specific genes hypothesized to play a role in the efficiency of predation/herbivory, will be targeted. If invasiveness has a molecular basis, we expect that basic digestive enzymes (e.g. a-amylases), metabolic genes (eg. ATPases), sensory genes (e.g. opsin genes), or muscle genes (e.g. tropomyosin) should be differentially expressed in invasive NIS versus native species. Our studies will also explore the importance of ambient temperature and life stages to these results.