Data from: Mitochondrial and microsatellite DNA markers reveal a Balkanic origin for the highly invasive Horse-Chestnut leaf miner Cameraria ohridella (Lepidoptera, Gracillariidae)

Biological invasions usually start with a small number of founder individuals. These founders are likely to represent a small fraction of the total genetic diversity found in the source population. Our study set out to trace genetically the geographical origin of the horse-chestnut leafminer, Cameraria ohridella, an invasive microlepidopteran whose area of origin is still unkown. Since its discovery in Macedonia twenty years ago, this insect has experienced an explosive westward range expansion, progressively colonizing all of Central and Western Europe. We used cytochrome oxidase I sequences (DNA barcode fragment) and a set of six polymorphic microsatellites to assess the genetic variability of C. ohridella populations, and to test the hypothesis that C. ohridella derives from the southern Balkans (Albania, Macedonia and Greece). Analysis of mtDNA of 486 individuals from 88 localities allowed us to identify 25 geographically structured haplotypes. In addition, 480 individuals from 16 populations from Europe and the southern Balkans were genotyped for 6 polymorphic microsatellite loci. High haplotype diversity and low measures of nucleotide diversities including a significantly negative Tajima's D indicate that C. ohridella has experienced rapid population expansion during its dispersal across Europe. Both mtDNA and microsatellites show a reduction in genetic diversity of C. ohridella populations sampled from artificial habitats (e.g. planted trees in public parks, gardens, along roads in urban or sub-urban areas) across Europe compared to C. ohridella sampled in natural stands of horse-chestnuts in the southern Balkans. These findings suggest that European populations of C. ohridella may indeed derive from the southern Balkans.生物入侵通常始于少量奠基者个体（founder individuals）。这些奠基者个体往往仅能代表源种群（source population）中全部遗传多样性（genetic diversity）的一小部分。本研究旨在从遗传学角度追溯奥氏七叶树潜蛾（Cameraria ohridella）的地理起源（geographical origin），该物种为一种入侵性微鳞翅目昆虫（microlepidopteran），其原生分布区域至今仍未明确。该物种自20年前在马其顿被发现以来，已呈现爆发式向西扩散态势，逐步侵占了整个中欧与西欧地区。本研究采用细胞色素氧化酶I序列（cytochrome oxidase I sequences，即DNA条形码片段（DNA barcode fragment））与6个多态微卫星标记（polymorphic microsatellites）组合，对奥氏七叶树潜蛾种群的遗传变异性（genetic variability）进行评估，并验证其起源于巴尔干半岛南部（阿尔巴尼亚、马其顿与希腊）的假说。对来自88个采样点的486头个体的线粒体DNA（mtDNA）进行分析，共鉴定出25种具有地理分布格局的单倍型（haplotypes）；此外，我们对来自欧洲与巴尔干半岛南部16个种群的480头个体，针对6个多态微卫星位点（polymorphic microsatellite loci）完成了基因分型（genotyped）。较高的单倍型多样性与较低的核苷酸多样性，结合显著为负的塔伊马D统计量（Tajima's D），表明奥氏七叶树潜蛾在跨欧洲扩散的过程中经历了快速种群扩张（rapid population expansion）。相较于在巴尔干半岛南部天然七叶树林中采集的奥氏七叶树潜蛾种群，欧洲范围内人工生境（artificial habitats，如公共公园、花园及城市/郊区道路旁种植的七叶树）中的奥氏七叶树潜蛾种群，其线粒体DNA与微卫星标记均表现出遗传多样性降低的特征。上述研究结果表明，欧洲的奥氏七叶树潜蛾种群确实可能起源于巴尔干半岛南部。