Dissertation Research: Systematics and Biogeography of Cryosophila (Palmae)

研究生埃文斯在密歇根大学教师顾问安德森的指导下，正在研究中南美洲嗜冷菌属棕榈树的物种关系和地理分布。这是一群中等大小，主要是低海拔的热带雨林棕榈树，分布在太平洋沿岸的墨西哥到哥伦比亚西北部。嗜冷菌可能只有不到10个不同的物种，但每个物种的确切数量以及定义特征和分布尚不清楚。本研究的第一个目标是对所有嗜冷菌进行鉴定、定义和分类，并确定它们的自然分布。一旦这一基本的分类信息被知道，该属内物种的进化历史将被用系统发育(分支)分析来推测，包括对白果属和伊塔亚棕榈属的研究。嗜冷菌属于棕榈亚族中最原始的一类，即棕榈亚族。虽然专门的棕榈树种群往往局限于北半球或南半球，但海雀棕榈树在两个半球的比例大致相同。然而，在新大陆，嗜冷棕榈树是唯一一种以中美洲为中心，延伸到南美洲和墨西哥的海雀属棕榈树。该属新物种的进化方向应该有助于确定物种形成的区域和物种形成事件的时间。棕榈科是一种形态多样的热带至亚热带类群，约有2600种，其中大部分仅限于雨林生境。由于这些森林的迅速破坏，以及绝大多数棕榈树物种只在野外发现，从未种植过，棕榈科植物的物种多样性受到严重威胁。由于大多数棕榈树在历史上都被采集得很差，因此在标本收藏中的代表性很低，因此棕榈树在野外的消失将意味着该家族内令人难以置信的多样性将永远得不到了解。从经济角度来看，棕榈树数量的减少将对热带国家产生重大影响，因为棕榈树为当地和地区以及出口提供了大量有用的产品。不幸的是，这个问题的严重性很难评估，保护措施也很难实施，因为许多棕榈树物种的定义很差，和/或对它们的分布只有部分了解。也就是说，良好的分类和生物地理数据对棕榈树保护工作至关重要，因为只有当物种可识别并知道其分布时，才能采取行动以可持续的方式捕捞它们并保护它们。这项由这笔赠款支持的研究旨在为中美洲棕榈树的一类(嗜冷菌属)提供这样的信息。

Graduate student Evans, under the direction of faculty adviser Anderson at the University of Michigan is studying the species relationships and geographical distributions of palms of the genus Cryosophila of Central and South America. This is a group of medium-sized, primarily low-elevation rainforest palms, distributed from Pacific coastal Mexico to northwestern Colombia. There are probably fewer than 10 distinct species of Cryosophila, but the exact number as well as the defining characteristics and distributions of each species are unknown. The first objective of this study is to identify, define and classify all Cryosophila species and determine their natural distributions. Once this basic taxonomic information is known, the evolutionary history of the species within the genus will be hypothesized using phylogenetic (cladistic) analysis, including study of Chelyocarpus and Itaya palms. Cryosophila belongs to the most primitive group of palms, the subtribe Thrinacinae. Whereas specialized groups of palms tend to be restricted to either the northern or southern hemisphere, thrinacine palms are more or less equally represented in both hemispheres. In the New World, however, Cryosophila is the only thrinacine palm having a distribution centered in Central America with extensions into both South America and Mexico. The direction of evolution of new species in the genus should help determine areas of speciation and timing of speciation events. The family Palmae is a morphologically diverse tropical to subtropical group having approximately 2600 species, most of which are restricted to rainforest habitats. Due to the rapid destruction of these forests and the fact that a large majority of palm species are found only in the wild and have never been cultivated, species diversity in the palm family is seriously threatened. Since most palms have historically been poorly collected and consequently are greatly under-represented in herbarium collections, the disappearance of palms in the wild will mean that the incredible diversity within the family will forever remain poorly understood. From an economic standpoint, declining palm populations will have major consequences for tropical nations because palms provide an enormous array of useful products for local and regional use as well as for export. Unfortunately, the severity of the problem is difficult to assess and protective measures difficult to implement because many palm species are poorly defined and/or their distributions are only partially understood. That is, good taxonomic and biogeographic data are critical for palm conservation efforts, for only when species are identifiable and their distributions known can actions be taken to harvest them in sustainable fashion and to protect them. The research supported by this grant is designed to provide just such information for one group (the genus Cryosophila) of Mesoamerican palms.