Ecology and evolution of host/parasite interactions

宿主/寄生虫相互作用的生态学和进化

• 批准号: RGPIN-2014-05142
• 负责人: Detwiler, Jillian
• 金额: $ 1.75万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611465
• 关键词: Ecology; evolution; host; parasite; interactions

The long term goal of my research program is to advance our knowledge of host-parasite interactions from an evolutionary ecology perspective because this approach is critical to establishing how and why disease spreads, evolves, and impacts hosts over space and time. In the field of evolutionary ecology, it is common to view parasites as agents of natural selection and focus on how parasites impact host biology. From the host perspective, parasites can alter individual host behaviors, regulate host populations, and constitute important components in food-webs. This one-sided perspective ignores parasite diversity and the potential implications it has for host biology. Not only is parasitism one of the most common forms of life, but parasites are also extremely diverse, meaning that there are many taxa that have independently evolved a parasitic lifestyle. Moreover, there is a diversity in life cycles, reproductive modes, host species, and ecosystems utilized by parasites. Yet, parasite biodiversity is underestimated and for many species very few aspects of their biology is known. My work over the next five years will integrate field and molecular data with ecological, phylogenetic, and population genetic analyses to reveal novel insights into parasite biodiversity, host specificity, and parasite-mediated selection on host immune response genes. My research on parasites will focus on discovering and characterizing parasite biodiversity in echinostomes trematodes. Echinostomes are a group of flatworm parasites that exemplify diversity in terms of species richness (>100 named species) and host species utilized (e.g. up to 29 used by one echinostome species). The variation exhibited by this group provides a great opportunity to study parasite evolution; however, efforts have been stymied by the taxonomic uncertainty as genetic evidence suggests that some individual species may in fact be complexes of several distinct species. My research addresses this problem by using molecular and morphological tools to identify and place echinostome species into a phylogenetic context, and then to recognize the hosts (vertebrates and invertebrates) which are responsible for maintaining and spreading disease. With these results, future studies can evaluate broad scale evolutionary or ecological topics such as speciation, hybridization, character evolution, and community trophic dynamics. In addition, the genetic database of echinostomes will prevent misidentification, and help determine which echinostome species play a significant role in wildlife disease, including amphibian decline. My research on hosts will investigate how parasites have influenced adaptively important regions of the host genome. I will focus on the major histocompatibility complex (MHC) because this region is a highly variable, genetic component of the vertebrate immune system that helps combat macroparasite infections (i.e. flatworms, nematodes, and arthropods). Relatively few studies have investigated, let alone differentiated between the mechanisms of parasite-mediated selection on MHC in natural populations. To do so, I will use a gecko-parasite system because large gecko sample sizes are obtainable and their parasites are easy to identify and quantify. By characterizing gecko MHC and then testing among the mechanisms of parasite-mediated selection, I will fill phylogenetic gaps in vertebrate MHC evolution, and clarify which mechanisms have most impacted natural populations. This knowledge will reveal how important genetic variation at the MHC is to the overall health of natural populations, which is thought to be critical to the long term survival and viability of natural populations.

我的研究计划的长期目标是从进化生态学的角度增进我们对宿主与寄生虫相互作用的了解，因为这种方法对于确定疾病如何以及为何在空间和时间上传播、进化和影响宿主至关重要。在进化生态学领域，通常将寄生虫视为自然选择的媒介，并关注寄生虫如何影响宿主生物学。从宿主的角度来看，寄生虫可以改变宿主个体的行为，调节宿主群体，并构成食物网的重要组成部分。这种片面的观点忽视了寄生虫的多样性及其对宿主生物学的潜在影响。寄生不仅是最常见的生命形式之一，而且寄生虫也极其多样化，这意味着有许多类群独立进化出了寄生生活方式。此外，寄生虫的生命周期、繁殖方式、宿主物种和生态系统也存在多样性。然而，寄生虫的生物多样性被低估了，对于许多物种来说，其生物学方面知之甚少。 我未来五年的工作将把现场和分子数据与生态、系统发育和群体遗传分析相结合，以揭示对寄生虫生物多样性、宿主特异性和寄生虫介导的宿主免疫反应基因选择的新见解。我对寄生虫的研究将集中于发现和表征棘口吸虫中的寄生虫生物多样性。棘口虫是一组扁形虫寄生虫，在物种丰富度（> 100 个命名物种）和利用的宿主物种（例如，一个棘口虫物种使用多达 29 种）方面具有多样性。该群体表现出的变异为研究寄生虫进化提供了绝佳的机会。然而，分类学的不确定性阻碍了这一努力，因为遗传证据表明某些单个物种实际上可能是几个不同物种的复合体。我的研究通过使用分子和形态学工具来识别棘口动物物种并将其置于系统发育背景中，然后识别负责维持和传播疾病的宿主（脊椎动物和无脊椎动物）来解决这个问题。利用这些结果，未来的研究可以评估广泛的进化或生态主题，例如物种形成、杂交、性状进化和群落营养动态。此外，棘口动物的遗传数据库将防止错误识别，并有助于确定哪些棘口动物物种在野生动物疾病（包括两栖动物数量减少）中发挥着重要作用。 我对宿主的研究将调查寄生虫如何影响宿主基因组的适应性重要区域。我将重点关注主要组织相容性复合体 (MHC)，因为该区域是脊椎动物免疫系统的高度可变的遗传组成部分，有助于对抗大型寄生虫感染（即扁虫、线虫和节肢动物）。调查研究相对较少，更不用说区分自然群体中寄生虫介导的 MHC 选择机制了。为此，我将使用壁虎寄生虫系统，因为可以获得大量壁虎样本，并且它们的寄生虫很容易识别和量化。通过表征壁虎 MHC，然后测试寄生虫介导的选择机制，我将填补脊椎动物 MHC 进化中的系统发育空白，并阐明哪些机制对自然种群影响最大。这些知识将揭示 MHC 的遗传变异对自然种群的整体健康有多么重要，这被认为对自然种群的长期生存和活力至关重要。