Beetles and Their Yeast Associates from Basidiocarp Habitats

抽象的。真菌通常被认为是植物多样性的决定因素，植物多样性被认为是影响甲虫和其他昆虫种群多样性的主要因素。然而，真菌和昆虫进化之间的直接关系仍然没有得到充分的认识。众所周知，包括酵母菌在内的肠道真菌对一些昆虫的营养至关重要。目前的研究是基于之前NSF支持的研究的结果，在这些研究中，PI从选定的巴拿马和美国地区的27个科的甲虫的消化道中分离出约200个新的酵母菌物种，占所有已知酵母物种的30%。统计分析估计，仅对先前采样的受限生境进行重新采样可能会产生额外的未描述的分类群，从而使全球所有生境的当前酵母菌数量增加50%。与甲虫相关的未描述酵母的巨大多样性的发现令人震惊，特别是当一个人超出这项研究的高度受限的分类学、时间、生态和地理范围的时候。系统发育分析将甲虫肠道酵母菌归入所有已知酵母中的至少45个独立支系，主要昆虫相关类群聚集在一起，这表明常见生境中偶尔的水平传播以及随后与昆虫的专业化产生了高度的酵母多样性。除了发现新的酵母物种外，目前的研究还将解决生理、生态和进化问题，涉及酵母-昆虫协会的性质、协会在世界范围内的普遍性，以及酵母在昆虫栖息地扩展和物种形成中可能发挥的作用，PI将使用田间和培养方法以及包括DNA测序在内的分子技术来回答这些问题。这项研究将具有更广泛的科学意义，因为酵母在工业过程中具有巨大的潜力。在这项工作中，PI发现与摄取木材的甲虫相关的酵母菌具有将植物原料高效转化为燃料酒精的潜力。其他新发现的酵母菌合成了各种各样的其他酶和维生素，PI将合作确定这些是否可能在工业过程中有用。私人投资调查将继续保持高度互动，并将广泛传播这项研究的结果。另一个好处是继续对本科生和研究生进行现代进化论和生态学研究方法的培训，就像以前的研究一样。除了对研究生进行培训外，个人投资促进机构特别有效地利用前一个项目作为重点，对17名本科生进行了昆虫-真菌协会各方面的培训；其中包括4名男性和13名女性，其中两名是少数族裔女性。所有毕业的学生都读过研究生或医学院，其中一位是牛津大学的乔治·C·马歇尔学者。发表了四篇有本科生作者的论文，并在全国会议上发表了两篇涉及本科生的演讲。

Abstract. Fungi often have been suggested as determinants of plant diversity, and plant diversification has been implicated as a major factor affecting the diversity of beetles and other insect groups. Direct relationships between fungi and insect evolution, however, remain under appreciated. Gut-inhabiting fungi, including yeasts, are known to be essential to the nutrition of some insects. The current study is based on results of previous NSF supported research in which the PIs isolated about 200 new species of yeasts out of 650 isolates from digestive tracts of beetles in 27 families in selected Panamanian and USA localities, an increase of 30% of all known yeast species. Statistical analyses estimate that resampling of only the previously sampled restricted habitats could produce additional undescribed taxa to increase current yeast numbers from all habitats worldwide by 50%. The discovery of the great diversity of undescribed yeasts in association with beetles is stunning, especially when one extrapolates beyond the highly restricted taxonomic, temporal, ecological, and geographical scope of this study. Phylogenetic analyses placed the beetle gut yeasts in at least 45 independent clades among all known yeasts with clustering of major insect-associated groups, suggesting high yeast diversity arose by occasional horizontal transmission in common habitats and subsequent specialization with the insects. In addition to discovery of new yeast species the current study will attack physiological, ecological, and evolutionary questions, regarding the nature of the yeast-insect associations, the universality of associations worldwide, and the role that yeasts may play in habitat expansion and speciation of insects, and the PIs will use field and cultural methods as well as molecular techniques, including DNA sequencing to answer the questions. The study will have broader scientific significance because yeasts have great potential in industrial processes. In this work the PIs discovered that yeasts associated with wood-ingesting beetles have potential in efficient conversion of plant material to fuel alcohol. Other newly discovered yeasts synthesize a wide variety of other enzymes and vitamins, and the PIs will collaborate to determine if these might be useful in industrial processes. The PIs will continue to be highly interactive and will disperse the findings of this study widely. An added benefit will be the continued training of undergraduates and graduate students in methods of modern evolutionary and ecological studies as in the previous study. In addition to the training of graduate students, the PIs were especially effective in using the previous project as a focus for training 17 undergraduates on aspects of insect-fungus associations; these included 4 men and 13 women, two of whom were minority women. All graduated students have gone to graduate or medical school; one is a George C. Marshall Scholar at Oxford University. Four papers with undergraduate authors were published, and two presentations at national meetings involved undergraduates.