DISSERTATION RESEARCH: Tracking trends in the lichen symbiosis: do species interactions drive the latitudinal diversity gradient?

纬度多样性梯度是指在赤道附近的热带地区发现了许多物种，而在热带地区以外的北极和南极发现的物种较少的模式。这种模式通常用温度、气候或地质条件来解释。纬度梯度很少被描述为生物相互作用;不同生物之间的相互作用。本研究调查了一个特殊的生物相互作用，地衣共生，沿着一个大的环境梯度从北美到南美。地衣是真菌和藻类/蓝藻之间的共生体（互利，长期，密切的物理联系）。尽管地衣很小，而且经常被忽视，但它几乎可以在每一个陆地环境中找到，使其成为研究大环境梯度中生物相互作用的理想选择。这项研究将侧重于共生在驱动多样性模式中的作用，并可能改善对气候持续变化中多样性模式如何变化的预测。这项研究独特地解决了共生关系中的两个伙伴，并将通过发现和描述新物种和特征来增加我们对全球生物多样性的了解。该项目将通过支持从描述模式到机械过程的研究来扩展博士生的研究和培训。一个关于共生的研讨会将提供给密歇根州的本科生，高中课堂的教育材料将通过数据掘金计划提供，促进科学过程，并可能在大学一级招募更多的科学和技术学生。生物相互作用假说提出，在热带以外的地区，非生物选择压力施加更强的力量，而在热带地区，生物选择压力施加更强的力量。此外，这些生物的相互作用导致了适应的移动高峰和共同进化的种族，这进一步促进了热带地区的多样化。本研究探讨动态的地衣共生沿着一个纬度梯度测序真菌和藻类的合作伙伴在5个地衣形成的真菌家族发现沿着纬度梯度，以映射模式的合作伙伴之间的特异性，并测试是否合作伙伴开关导致多样化的事件或范围的变化，地衣共生。

The latitudinal diversity gradient is the pattern in which many species are found in the tropics, near the equator, and fewer species are found outside of the tropics, towards the North and South poles. This pattern is often explained in terms of temperature, climate, or geological conditions. Less frequently, the latitudinal gradient is described in terms of biotic interactions; interactions between different organisms. This research investigates a particular biotic interaction, the lichen symbiosis, along a large environmental gradient from North to South America. Lichens are symbioses (mutually beneficial, long-term, close physical associations) between fungi and algae/cyanobacteria. Though small and often overlooked, lichens can be found in almost every terrestrial environment, making them ideal for investigating biotic interactions across large environmental gradients. This research will focus on the role of symbiosis in driving patterns of diversity, and may improve predictions of how patterns of diversity change in the face of ongoing changes in climate. This research uniquely addresses both partners in the symbiosis, and will increase our knowledge of global biodiversity through the discovery and description of new species and traits. This project will extend the research and training of a doctoral student by supporting research that moves from descriptive pattern to mechanistic process. A workshop on symbioses will be made available to undergraduate students in Michigan, and educational materials for high school classrooms will be offered via the Data Nugget program, promoting the scientific process and potentially recruiting more students to science and technology at the college level. The biotic interactions hypothesis proposes that in extra-tropical regions, abiotic selective pressures exert a stronger force, whereas in tropical regions, biotic selective pressures exert a stronger force. Furthermore, these biotic interactions lead to moving peaks of adaptation, and coevolutionary races, which further contributes to diversification in the tropics. This research investigates the dynamics of the lichen symbiosis along a latitudinal gradient by sequencing both the fungal and algal partners within five lichen-forming families of fungi found along the latitudinal gradient in order to map patterns of specificity among partners, and to test whether partner switches have resulted in diversification events or range shifts in the lichen symbiosis.