DISSERTATION RESEARCH: The ax and wedge of competition shapes symbiont diversity

共生这个术语有许多专业和非专业的定义，但这里的共生仅仅意味着两个物种的生命通过交换资源和服务或提供栖息地而紧密联系在一起，例如当一个生物生活在另一个生物身上或体内时。大多数植物和动物都是共生的。在许多情况下，有机体离不开它们的共生体。此外，一个生物体的生命可能依赖于与许多种类的共生体的多种共生相互作用。例如，人类的营养、发育和免疫功能取决于与成千上万的内部和外部细菌物种的相互作用。然而，目前的共生理论不能解释共生群落多样性的进化和维持。该项目将探索与小龙虾共生的蠕虫物种之间的生态和进化相似性模式，以展示共生体之间的竞争如何通过排除竞争较弱的物种来限制共生体的多样性，但也通过有利于新共生体物种的进化来创造多样性。因为共生体的多样性对生物体来说是必要的吗？在快速变化的世界中，要预测许多物种的命运，就需要了解共生多样性。因此，这项工作将对诸如保护、流行病学和农业等不同领域产生深远的影响。拟议的工作包括与迈克·罗森茨威格博士合作，他是弗吉尼亚理工大学生物科学推广项目“寻求教育、探索和发现”（SEEDS）项目的主任。调查人员将在弗吉尼亚州布莱克斯堡的普莱斯豪斯自然中心通过公开讲座和演示来传播他们的发现。这些活动将提高公众对发生在后门之外的有趣共生的认识，并提供与迷人的本地物种的第一手经验。竞争可能在塑造当地生物多样性方面发挥双重作用；它可以通过竞争性排斥限制本地多样性，也可以通过破坏性选择创造多样性。仅仅观察当代的模式并不能区分这两个过程，因为两者产生相似的模式。拟议的工作将超越共生组合的当代模式，以寻找创造和塑造共生多样性的进化过程的证据的系统发生史。为了阐明创造共生多样性的进化过程，研究人员将结合功能性状的生态数据和生物多样性模式的大规模评估，以及利用基因序列数据对进化史进行系统发育重建。

The term symbiosis has many technical and non-technical definitions, but here symbiosis simply means that the lives of two species are intimately linked by exchanges of resources and services or provisioning of habitat, such as when one organism lives on or inside another. Most plants and animals are engaged in symbioses. In many cases, organisms cannot live without their symbionts. Moreover, the life of an organism may depend on many kinds of symbiotic interactions with many kinds of symbionts. For instance, human nutrition, development, and immune function depend on interactions with thousands of internal and external bacterial species. However, current symbiosis theories cannot account for the evolution and maintenance of diversity in symbiont communities. The proposed project will explore patterns of ecological and evolutionary similarities among species of worms which live in symbiosis with crayfish to show how competition among symbionts can limit symbiont diversity by excluding less competitive species, but also create diversity by favoring the evolution of new symbiont species. Because symbiont diversity is often necessary for an organism?s survival, an understanding of symbiont diversity is needed to predict the fate of many species in a rapidly changing world. Therefore this work will have far-reaching implications for disparate fields such as conservation, epidemiology, and agriculture. The proposed work includes a collaboration with Dr. Mike Rosenzweig, director of the Seek Education, Explore, and DiScover (SEEDS) program as part of the Virginia Tech Biological Science Outreach. The investigators will disseminate their findings through public lectures and demonstrations at the Price House Nature Center in Blacksburg, Virginia. These activities will raise public awareness of the intriguing symbioses that occur just beyond their back door and provide a first-hand experience with charismatic native species. Competition may play a dual role in shaping local biodiversity; it can limit local diversity through competitive exclusion, or it can create diversity through disruptive selection. Observation of contemporary patterns alone cannot distinguish these processes because both yield similar patterns. The proposedwork will extend beyond contemporary patterns of symbiont assemblages to search phylogenetichistory for evidence of the evolutionary processes that create and shape symbiont diversity. The researchers will do this by combining ecological data of functional traits and broad scale assessment of patterns in biodiversity with a phylogenetic reconstruction of evolutionary history using genetic sequence data, in order to elucidate the evolutionary processes that create symbiont diversity.