Plant and Soil Science Department, University of Vermont, Burlington, VT, United States of America.
Plant Biology Department, University of Vermont, Burlington, VT, United States of America.
PeerJ. 2022 Jul 13;10:e13622. doi: 10.7717/peerj.13622. eCollection 2022.
The invasive Asian earthworms, and , have been successful in entering North American forests in recent decades, with significant damage to both soils and above-ground environments. This success could be driven in part by a polyploid genetic system and parthenogenetic reproduction, often suggested as benefits for invasive species. Therefore, we assessed the genetic population structure, genetic diversity, and reproductive system of both species using morphological traits and panels of microsatellite markers. A total of 216 and 196 from six sites in Vermont USA were analyzed. Although all worms were morphologically hermaphroditic, all the lacked the male pore (the structure allowing pass of sperm between individuals), and only 19% of the possessed the male pore. All earthworms were triploid (scored for three alleles for at least 1 locus, and usually several), and was a mix of triploid and diploid individuals. Notable was the high proportion (80%) of earthworms that were diploid at one site. There was clearly clonal reproduction, with identical seven- locus genotypes observed for earthworms from each site, with as many as 45 individuals with the identical genotype at one site. However, the earthworms were also genetically diverse, with 14 genotypes observed for and 54 for , and with many singleton genotypes (a single individual). Most genotypes (71% for and 92% for ) were found at a single site. The greatest number of genotypes was found at a commercial nursery where fully 23/26 earthworms were singleton genotypes. As expected for the pattern of private clone alleles at sites, several measures of geographic genetic differentiation were positive, and as expected for triploid systems, an AMOVA analysis showed high within-individual genetic diversity. The paradox of clear clonal reproduction, but with a great number of genotypes for each species, and the mix of triploid and diploid individuals could be explained if the worms have been sexually reproductive, with the switch to the uniparental system only recently (or even if sexual reproduction is episodic). Last, a large number of microsatellite loci were recovered for each species and there sequence and suggested PCR primers are provided for free use by other researchers.
入侵亚洲蚯蚓 和 ，近几十年来成功进入北美森林，对土壤和地上环境造成重大破坏。这种成功部分可能是由多倍体遗传系统和孤雌生殖所驱动的，通常被认为是入侵物种的优势。因此，我们使用形态特征和微卫星标记面板评估了这两个物种的遗传种群结构、遗传多样性和生殖系统。共分析了来自美国佛蒙特州六个地点的 216 条 和 196 条 。尽管所有的蚯蚓在形态上都是雌雄同体的，但所有的 都没有雄性孔（允许个体之间精子通过的结构），只有 19%的 拥有雄性孔。所有的 蚯蚓都是三倍体（至少有 1 个位点评分有 3 个等位基因，通常有几个），而 是三倍体和二倍体个体的混合体。值得注意的是，在一个地点， 蚯蚓的二倍体比例很高（80%）。显然存在克隆繁殖，每个地点的蚯蚓都观察到相同的七个位点基因型，在一个地点，多达 45 个个体具有相同的基因型。然而，蚯蚓的遗传多样性也很高， 观察到 14 种基因型， 观察到 54 种基因型，并有许多单倍体基因型（单个个体）。大多数基因型（ 71%）和 （92%）都在一个单一的地点发现。在一个商业苗圃中发现了最多的基因型，在那里 26 条 蚯蚓中有 23 条是单倍体基因型。正如预期的那样，在各地点的私有克隆等位基因模式下，几种地理遗传分化的衡量标准是阳性的，并且正如预期的那样，在三倍体系统中，AMOVA 分析显示个体内遗传多样性很高。如果蚯蚓具有有性生殖，那么明确的克隆繁殖与每个物种的大量基因型以及三倍体和二倍体个体的混合现象就可以得到解释，这种有性生殖的转变可能是最近发生的（或者即使有性生殖是偶发性的）。最后，为每个物种回收了大量的微卫星位点，并提供了序列和建议的 PCR 引物供其他研究人员免费使用。
