Molecular Systematics of the Lower Lepidoptera

昆虫是生物中最多样化的一类，昆虫之间的系统发育关系是一个尚未解决的主要系统问题。核苷酸序列特征可能是答案的关键部分，但只有少数研究，主要是基于同一基因。一个模型系统是庞大的鳞翅目（15万种），是无数比较研究项目的主题，其基础关系研究得很好，为新分子的效用提供了强有力的检验。在这个项目之前，计算机搜索、Southern杂交和聚合酶链反应（PCR）研究被用来确定五个以前未测试的核基因，它们似乎适合更高水平的系统发育（延伸因子- 1 (α)， RNA聚合酶II的最大亚基，多巴脱羧酶，延伸因子-2，磷酸烯醇丙酮酸羧激酶）。对这5个基因和核糖体RNA基因合成了寡核苷酸引物，并在原始鳞翅目和相关的全景目中进行了成功的基因组扩增试验。从6个和11个分类群的PCR产物中直接测序了部分延伸因子-1 （α）和核糖体基因。在几种分析方法下，得到的树与形态学一致。进一步的研究将通过对15个物种的延伸因子1 （α）、RNA聚合酶II和核糖体基因的更大部分测序来完成对潜在信息核基因的评估，这些物种在基础鳞翅目和密切相关的目中共同代表了强有力的形态学支持的关系。通过对每个基因的独立分析构建的树将被测试彼此之间以及与形态系统发育的一致性。对于显示出强烈一致性的基因，分析将扩展到另外20种蛾类，这些蛾种的样本，一式两份，所有主要的低鳞翅目谱系，包括有问题的关系；此外，足够保守的基因将被用于更广泛地研究全景目之间的关系。

Phylogenetic relationships within insects, the most diverse class of organisms, are a major unsolved systematic problem. Nucleotide sequence characters could be a key part of the answer, but there have been only a few studies, based mostly on the same gene. One model system is the enormous order Lepidoptera (150,000 species), subject of innumerable comparative research programs whose well-studied basal relationships provide a strong test for the utility of new molecules. Prior to this project, computer search, Southern hybridization, and polymerase chain reaction (PCR) studies were used to identify five previously untested nuclear genes which appear suitable for higher-level phylogenetics (elongation factor-l (alpha), the largest subunit of RNA polymerase II, dopa decarboxylase, elongation factor-2, phosphoenolpyruvate carboxykinase). Oligonucleotide primers were synthesized for all five genes, plus the nuclear ribosomal RNA gene, and tested for successful genomic amplification in primitive Lepidoptera and related panorpoid orders. Portions of the elongation factor-1 (alpha) and ribosomal genes have been sequenced directly from PCR products for 6 and 11 taxa, respectively. The resulting trees, under several analytical methods, show concordance with morphology. Additional studies will complete evaluation of potentially informative nuclear genes by sequencing larger portions of elongation factor 1 (alpha), RNA polymerase II and the ribosomal gene in 15 species that together represent relationships strongly supported by morphology within basal Lepidoptera and closely related orders. Trees constructed by independent analyses of each gene will be tested for concordance with each other and with the morphological phylogeny. For genes showing strong concordance, the analysis will then be extended to an additional 20 moth species that sample, in duplicate, all major lower lepidopteran lineages, including problematic relationships; sufficiently conservative genes will additionally be used to initiate a broader study of relationships among panorpoid orders.