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

共生这个词有许多技术性和非技术性的定义，但在这里，共生只是指两个物种的生命通过资源和服务的交换或栖息地的提供而紧密相连，例如当一个有机体生活在另一个有机体上或体内时。大多数植物和动物都参与了共生。在许多情况下，生物体没有共生体就不能生存。此外，生物体的生命可能依赖于与多种共生体的多种共生相互作用。例如，人类的营养、发育和免疫功能依赖于与数以千计的内外细菌物种的相互作用。然而，目前的共生理论不能解释共生体群落中多样性的进化和维持。拟议的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，但也通过有利于新的共生体物种的进化来创造多样性。因为共生体的多样性通常是有机体生存所必需的，所以需要对共生体多样性的了解来预测许多物种在快速变化的世界中的命运。因此，这项工作将对保护、流行病学和农业等不同领域产生深远影响。拟议的工作包括与Seek Education，Explore，and Discovery(种子)项目主任Mike Rosenzweig博士合作，作为弗吉尼亚理工大学生物科学外展的一部分。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示威活动传播他们的发现。这些活动将提高公众对发生在他们后门之外的有趣共生的认识，并提供对富有魅力的本土物种的第一手体验。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当地多样性，也可以通过破坏性选择创造多样性。仅仅观察当代的模式不能区分这些过程，因为两者都产生了相似的模式。这项拟议的工作将超越共生生物组合的当代模式，以寻找创造和塑造共生生物多样性的进化过程的证据。研究人员将通过将功能特征的生态数据和对生物多样性模式的广泛评估与使用遗传序列数据重建进化史的系统发育相结合来实现这一点，以阐明创造共生生物多样性的进化过程。

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.