DISSERTATION RESEARCH: Foliar and floral evolution in geographic context: cryptic evolution in the mycoheterotrophic Pyrola picta species complex (Ericaceae)

鹿蹄草属（学名：scotophyla）生长在北美西部，具有几个有趣的生命史属性，这些属性在不同物种之间有所不同，本研究将对其进行调查。这些包括直接从真菌中获取营养的特殊策略（即，真菌异养），从大的和光合作用的到小的和无功能的叶子，以及由大黄蜂授粉但在没有蜜蜂的情况下保留自花授粉能力的花。至少有两项发现使我们对苦叶科物种如何实现（并维持）生殖隔离的一般理解复杂化。首先，在复合体中发现的隐种表明，不同的遗传谱系已经融合在一个非常相似的形式上。其次，在物种共存的种群中发现了低频率的物种间杂交。为了了解基因流动与物种形成和形态多样性之间的关系，本研究利用修订物种范围内植物的DNA序列信息，重点研究了scotophyla部分的系统地理学（即绘制地理和遗传谱系历史）。此外，本研究的重点是(1)了解混合交配系统如何促进基因流动和物种多样性；(2)确定生殖隔离破裂的原因；(3)了解发育时间如何在这种真菌异养植物谱系的叶片形态、解剖和功能进化中发挥作用。本研究将对鞘翅目中物种的地理分布范围进行修订，描述一个新的隐种，并对正在进行的关于隐种的认识如何影响我们对生物多样性的解释的论述做出贡献。作为成熟森林群落的基本共生元素，像鹿蹄草这样的真菌异养分类群可以有效地作为生态系统健康的指标，最终使生态学和进化更容易被广泛的受众所了解。随着时间的推移，了解鹿蹄草谱系的进化史可能最终改变人类？对北美西部自然历史和保护生物学家正在进行的努力的认识。这项研究的结果将发表在同行评议的期刊、科学会议和非科学论坛上，并作为对自然史感兴趣的学生和教师的解释性文献。

Species in genus Pyrola section Scotophylla (part of the Heath family) grow in western North America and possess several intriguing life history attributes that vary among species and will be investigated for this study. These include a special strategy for retrieving nutrition directly from fungi (i.e., mycoheterotrophy), leaves that range from large and photosynthetic to minute and non-functional, and flowers that are buzz-pollinated by bumble bees yet retain the ability to self-pollinate in the absence of bees. At least two findings complicate our general understanding of how species in section Scotophylla achieved (and maintain) reproductive isolation. First, the identification of cryptic species within the complex suggests that different genetic lineages have converged on a very similar form. Second, hybridization among species has been detected at low frequencies in populations where species co-occur. In order to understand how gene flow relates to speciation and morphological diversity, this study focuses on the phylogeography (i.e., mapping geographic and genetic lineage histories) of section Scotophylla using DNA sequence information from plants across revised species ranges. Additionally, this study focuses on (1) understanding how mixed-mating systems contribute to gene flow and species diversity, (2) determining the causes of breakdown in reproductive isolation, and (3) understanding how timing in development has played a role in the evolution of leaf morphology, anatomy, and function in this mycoheterotrophic plant lineage.This study will provide a revision of geographic ranges for species in section Scotophylla, the description of a new, cryptic species, and a contribution to ongoing discourse concerning how the recognition of cryptic species affects our interpretation of biological diversity. As fundamental, symbiotic elements of mature forest communities, mycoheterotrophic taxa like Pyrola serve effectively as indicators of ecosystem health, ultimately making ecology and evolution more accessible to a range of audiences. Understanding the evolutionary history of Pyrola lineages through time may ultimately change peoples? perceptions of both natural history and ongoing efforts by conservation biologists in western North America. Findings from this study will be available in peer-reviewed journals, at scientific conferences and in non-scientific forums, and as interpretive literature for students and teachers interested in natural history.