The sea hare Bursatella leachii (de Blainville 1817) (Mollusca: Gastropoda: Heterobranchia: Aplysiidae) is a pantropical sea slug that has colonized the Mediterranean Sea in modern times. Because the initial records in the non-native range started in the Eastern Mediterranean, and its pattern of spread was relatively consistent with those observed in well-known Lessepsian invaders, B. leachii is commonly considered to be a migrant from the Red Sea. In this study, we investigate for the first time the origin of the Mediterranean populations of B. leachii inferring their population structure and assessing relatedness levels of different regional populations. Sequence data from the cytochrome oxidase I were used to conduct population genetic analyses on this species, particularly by investigating the genetic structure of Atlantic, Mediterranean, and Indo-Pacific populations. Our results confirm that B. leachii is a truly pantropical species which displays geographic structure among major ocean basins. More importantly, sequenced Mediterranean and Atlantic animals share similar or identical haplotypes, which are distinct in at least 5 substitutions from haplotypes recovered from Indo-Pacific specimens. The results suggest that the Mediterranean population of B. leachii here examined probably have an Atlantic origin, and for the first time casts doubts on the assumed primary pathway of migration into the Mediterranean Sea.

中文翻译：

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Bursatella leachii（De Blainville，1817）的种群遗传学及其对地中海种群起源的影响

海兔Bursatella leachii（de Blainville，1817年）（软体动物：腹足纲：杂种翅目：鸭Ap科）是一种泛热带海参，在现代殖民了地中海。由于最初在非本地范围内的记录始于东地中海，并且其传播方式与在著名的莱斯比西斯入侵者中所观察到的相一致，因此一般认为Leachi B. leachii是从红海移民的。在这项研究中，我们首次调查了地中海芽孢杆菌种群的起源，以推断其种群结构并评估不同区域种群的亲缘关系水平。细胞色素氧化酶I的序列数据被用来对该物种进行种群遗传分析，尤其是通过研究大西洋，地中海沿岸，和印度太平洋人口。我们的结果证实，B。leachii是真正的泛热带物种，在主要海盆中显示出地理结构。更重要的是，经过测序的地中海和大西洋动物具有相似或相同的单倍型，这至少有5种替代与从印度太平洋标本中回收的单倍型不同。结果表明，在此检查的地中海B. leachii种群可能起源于大西洋，这首次使人们怀疑迁移到地中海的主要途径。与从印度太平洋标本中回收的单倍型相比，至少有5个替代特征。结果表明，在此检查的地中海盲蝇（B. leachii）种群可能起源于大西洋，这首次使人们对假定的向地中海迁移的主要途径产生了怀疑。与从印度太平洋标本中回收的单倍型相比，至少有5个替代特征。结果表明，在此检查的地中海B. leachii种群可能起源于大西洋，这首次使人们对假定的迁移到地中海的主要途径产生了怀疑。