DISSERTATION RESEARCH: Evolution of Generalism and Specialism in the RNA phage Phi6

生物学家长期以来一直困惑于为什么大多数生物只专注于少数资源，而不是通过广泛利用自然界提供的各种资源来推广。 泛用主义似乎是一种更有吸引力的策略，因为它允许更大的生态位空间和生物体在广泛的栖息地中茁壮成长的能力。 然而，专家似乎在自然界中占主导地位，这可能是因为他们在利用较少数量的资源方面效率更高。 通论的代价（及其潜在机制）已被证明是难以研究的。 这项研究将使用RNA病毒phi-6的突变体，这些突变体显示出感染新宿主细菌的能力增强（即，generalist viruses），以检查generalism的假设成本。 突变体将在一个新宿主上进化数百代，以测试适应新宿主是否需要特化（缩小病毒生态位）。 此外，进化病毒的基因组将被测序，以测试两种关于特化机制如何在分子水平上进化的相互竞争的理论。 这项研究是强大的，因为它使用了一种无害的细菌病毒来研究有关病毒转移到宿主上的一般问题。 病毒phi-6是一个特别有用的模型，用于研究分段RNA病毒的进化，如感染人类的汉坦病毒和流感病毒。 因此，研究结果应进一步了解宿主转移涉及病原性RNA病毒的高等生物。

Biologists have long puzzled why most organisms specialize on few resources, rather than generalize by broadly exploiting the wide variety of resources that nature offers. Generalism seems a more tempting strategy, because it allows a larger niche space and the ability for organisms to thrive across a vast range of habitats. However, specialists appear to predominate in nature, perhaps due to their greater efficiency at exploiting a lesser number of resources. The costs of generalism (and their underlying mechanisms) have proven difficult to study. This research will use mutants of the RNA virus phi-6 that show an expanded ability to infect new host bacteria (i.e., generalist viruses), to examine hypothesized costs of generalism. The mutants will be evolved for hundreds of generations on a single novel host in order to test whether adaptation to the new host necessitates specialization (narrowing of the virus niche). Also, genomes of the evolved viruses will be sequenced to test two competing theories on how mechanisms for specialization evolve at the molecular level. This study is powerful because it uses a harmless virus of bacteria to study general questions regarding host shifts by viruses onto hosts. Virus phi-6 is an especially informative model for studying evolution of segmented RNA viruses, such as Hantavirus and Influenza which infect humans. Thus, results of the study should further the understanding of host-shifts involving pathogenic RNA viruses of higher organisms.