Dissertation Research: Phylogeny, Host Plant Shifts, and Geographical Origin of the genus Trirhabda (Coleoptera: Chysomelidae)

0073200 Kjer和Swigonova甲虫的多样性，在昆虫目的鞘翅目下分组，远远超过任何其他动物或植物群体的多样性。由于超过一半的已知甲虫是草食性的，物种形成机制的研究与寄主植物的利用，以及潜在的协调进化的甲虫和它们的寄主植物（共同进化），应该提供见解，以了解明显的进化成功的甲虫。进化关系假说（同源性假说）为这种机制的研究提供了基础。叶甲（学名：Escheromelidae）属于第四大甲虫家族，是地球上最成功的生物之一。研究生Zuzana Swigonova博士建议卡尔Kjer，正在研究chrysomelid属Trirhabda，以确定物种之间的进化关系，确定密切相关的物种是否以密切相关的植物为食，揭示寄主植物偏好和寄主植物在物种之间转移的历史，揭示物种相关性和地理分布之间的任何模式，并确定该属最可能的地理起源地区。本论文研究了三杆属（鞘翅目：叶甲科）的叶甲，其中墨西哥以北的26种（“北方种”），墨西哥和中美洲的8种（“南方种”）。北方种已在许多生态学方面进行了研究，对它们的寄主植物偏好和生活史了解很多。 相反，没有关于南方种的寄主植物协会或生态学的信息。八种南方甲虫中有六种在墨西哥发现，北方甲虫以菊科和水螅科的一小部分植物为食。与其他科属不同的是，它们在卵期越冬。幼虫和成虫以寄主植物的叶子和花序为食。化蛹发生在寄主植物下面的土壤中。每一种三杆纲物种的生活史都受到其宿主植物生活史的强烈影响。 该属的几个北方物种已被用作生物制剂，在经历次生演替的田地中控制杂草。 尽管事实上，Trirhabda物种已被用于许多生态学研究，尽管一些物种的经济重要性，一直没有系统的研究提出本属内的evolutionaryrelations。系统发育关系将推断从三个独立的数据集：一个形态和两个分子。形态学数据将包括文献中描述的仔细检查和重新评估的特征。 新的字符，包括口部的感觉器，将使用扫描电子显微镜检查。 分子数据将包括线粒体小亚基核糖体RNA的DNA序列、线粒体细胞色素氧化酶的第一亚基和核核糖体ITS（内部转录间隔区）序列。

0073200Kjer and Swigonova The diversity of beetles, grouped under the insect order Coleoptera, far exceeds the diversity of any other animal or plant group. Because more than half of all known beetles are herbivorous, studies of mechanisms of speciation in relation to host plant utilization, and potential coordinated evolution of beetles and their host plants (coevolution), should provide insights to understanding the evident evolutionary success of beetles. Hypotheses of evolutionary relations(phylogeny) provide a foundation for the study of such mechanisms. The leaf beetles (Chrysomelidae) belong to the fourth largest family of beetles, making them among the most successful organisms on the earth. Graduate student Zuzana Swigonova, advised by Dr. Karl Kjer, is studying the chrysomelid genus Trirhabda, in order to determine evolutionary relationships among the species, determine whether closely related species feed on closely related plants, revealthe history of host plant preference and host plant shifts among the species, disclose any pattern between species relatedness and geographic distribution, and identify the area that is the most probable biogeographical origin of the genus. The dissertation focuses on leaf beetles of the genus Trirhabda(Coleoptera: Chrysomelidae) which contains 26 species from America north of Mexico ("northern species") and 8 species from Mexico and Central America ("southern species"). The northern species have been studied in many ecological aspects and much is known about their host plant preference and life cycle. In contrast, there is no information about host plant association or ecology of the southern species. Six out of the eight southern species are found in Mexico.Beetles of the northern species feed on a narrow range of plants in the families Asteraceae and Hydrophyllaceae. Unlike other species from the family Chrysomelidae, they overwinter in the egg stage. Larvae and adults feed on leaves and inflorescence of the host plant. Pupation takes place in the soil below the host plant. The life history of each of the Trirhabda species is strongly influenced by the life history of their host plant. Several northern species of the genus have been used as biological agents in control of weeds in fields undergoing secondary succession. Despite the fact that Trirhabda species have been used in many ecological studies and despite the economic importance of some of the species, there has been no systematic study proposing evolutionaryrelationships within this genus. Phylogenetic relationships will be inferred from three independent data sets: one morphological and two molecular. Morphological data will include carefully examined and reevaluated characters described in the literature. New characters, including sensillae of the mouth parts, are to be examined using scanning electron microscopy. Molecular data will include DNA sequences of mitochondrial small subunit ribosomal RNA, the first subunit of mitochondrial cytochrome oxidase, and nuclear ribosomal ITS (internal transcribed spacer) sequences.