DISSERTATION RESEARCH: Catching Sequential Speciation in the Act

了解新物种进化(物种形成)的过程是生物科学中的一个基本问题。一种流行的、但在很大程度上未经检验的观点是，一个物种的形成可以催化相互作用的有机体群落内其他物种的形成(顺序物种形成)。先前的研究表明，大约150年前，在美国东部，苹果蝇从原生的山楂寄主植物转移到引进的驯化苹果上，导致了攻击果蝇的昆虫寄生群落的连续宿主转移。具体地说，当苍蝇转移到攻击一种新寄主植物的果实时，攻击这种苍蝇的昆虫寄生虫也会发生同类转移。尚不清楚的是，自然界中顺序物种形成事件的普遍性和速度有多快。一种有效的方法是在美国西部一个更接近的案例中检验顺序物种形成假说，这种苍蝇最近才在50年前引入美国。这项拟议的研究将检查苍蝇及其寄生虫在这个新栖息地的变化，以更好地评估物种形成的速度。了解生物多样性的起源是生物科学的中心问题之一。在这方面，顺序物种形成对于了解一般生物多样性，特别是昆虫生物多样性的惊人水平可能特别相关(据估计，全世界有1000-3000万个物种，这是地球上最多样化的动物群体)。此外，苹果蝇及其近缘种也是几种农作物的主要经济害虫。对寄生蜂群落起源的描述可以为生物防治计划提供信息，帮助农民在苍蝇成为美国西部的严重害虫之前控制它。

Understanding the process by which new species evolve (speciation) is a fundamental question in biological sciences. A popular, but largely untested idea is that the formation of one species can catalyze the formation of other species within a community of interacting organisms (sequential speciation). Previous work has shown that a shift of the apple maggot fly from its native hawthorn host plant to the introduced domesticated apple about 150 years ago in the eastern US has induced a sequential host shift in the insect parasite community that attacks the flies. Specifically, as the fly shifts to attacking the fruits of a new host plant, the insect parasites that attack that fly shift in kind. What remains unknown is how general and rapid sequential speciation events are in nature. A powerful approach is to test the sequential speciation hypothesis in a more proximate case in the western US where the fly was recently introduced just 50 years ago. The proposed research will examine changes in the flies and their parasites in this new habitat to better evaluate the rate of speciation. Understanding the origins of biodiversity is one of the central issues in biological sciences. In this regard, sequential speciation may be particular relevant for understanding biodiversity in general and in particular the astonishing levels of insect biodiversity (estimated 10-30 million species worldwide, the most diverse group of animals on the planet). Additionally, the apple maggot fly and several closely related species are major economic pests of several agricultural crops. Characterization of the origins of the parasitoid community can inform bio-control schemes to help farmers control the fly before it becomes a serious pest in the western United States.