Bely Alexandra E, Weisblat David A
Department of Biology, University of Maryland, College Park, MD 20742, USA.
Evol Dev. 2006 Nov-Dec;8(6):491-501. doi: 10.1111/j.1525-142X.2006.00122.x.
Many evolution of development labs study organisms that must be periodically collected from the wild. Whenever this is the case, there is the risk that different field collections will recover genetically different strains or cryptic species. Ignoring this potential for genetic variation may introduce an uncontrolled source of experimental variability, leading to confusion or misinterpretation of the results. Leeches in the genus Helobdella have been a workhorse of annelid developmental biology for 30 years. Nearly all early Helobdella research was based on a single isolate, but in recent years isolates from multiple field collections and multiple sites across the country have been used. To assess the genetic distinctness of different isolates, we obtained specimens from most Helobdella laboratory cultures currently or recently in use and from some of their source field sites. From these samples, we sequenced part of the mitochondrial gene cytochrome oxidase I (COI). Sequence divergences and phylogenetic analyses reveal that, collectively, the Helobdella development community has worked on five distinct species from two major clades. Morphologically similar isolates that were thought to represent the same species (H. robusta) actually represent three species, two of which coexist at the same locality. Another isolate represents part of a species complex (the "H. triserialis" complex), and yet another is an invasive species (H. europaea). We caution researchers similarly working on multiple wild-collected isolates to preserve voucher specimens and to obtain from these a molecular "barcode," such as a COI gene sequence, to reveal genetic variation in animals used for research.
许多发育实验室的研究对象是那些必须定期从野外采集的生物。每当出现这种情况时，就存在不同野外采集样本可能获取到基因不同的菌株或隐性物种的风险。忽视这种遗传变异的可能性可能会引入一个不受控制的实验变异性来源，导致结果混淆或误解。在过去30年里，蛭形轮虫属的水蛭一直是环节动物发育生物学的研究主力。几乎所有早期关于蛭形轮虫的研究都基于单一分离株，但近年来，来自全国各地多个野外采集点和多个地点的分离株也被使用。为了评估不同分离株的遗传差异，我们从目前或最近使用的大多数蛭形轮虫实验室培养物及其一些野外来源地点获取了样本。从这些样本中，我们对线粒体基因细胞色素氧化酶I（COI）的部分序列进行了测序。序列差异和系统发育分析表明，总体而言，蛭形轮虫发育研究群体所研究的对象来自两个主要进化枝的五个不同物种。形态上相似且曾被认为代表同一物种（强壮蛭形轮虫）的分离株实际上代表了三个物种，其中两个在同一地点共存。另一个分离株代表一个物种复合体（“三列蛭形轮虫”复合体）的一部分，还有一个是入侵物种（欧洲蛭形轮虫）。我们提醒同样在研究多个野生采集分离株的研究人员保存凭证标本，并从这些标本中获取分子“条形码”，如COI基因序列，以揭示用于研究的动物的遗传变异。
