GeneCology Research Centre, School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD, 4556, Australia.
Department of Biology, Georgia Southern University, Statesboro, GA, 30458, USA.
Parasit Vectors. 2020 Feb 18;13(1):83. doi: 10.1186/s13071-020-3957-y.
Historical European exploration and colonization resulted in the introduction of four species of rodents to the Australian continent from Eurasia: the brown rat, Rattus norvegicus, the black rat, R. rattus, the Pacific rat, R. exulans, and the house mouse, Mus musculus. The spread of these rodents created opportunities for their co-introduced sucking lice to parasitize and adapt to endemic rodents in Australia.
We collected sucking lice from rodent specimens in seven museums across Australia. We identified the spiny rat louse, Polyplax spinulosa, based on morphology. We sequenced the mitochondrial cox1 and rrnL genes of P. spinulosa specimens and constructed a phylogenetic tree with rrnL sequences.
We examined 989 rodent specimens of 54 species and collected 2111 adult sucking lice and 1064 nymphal sucking lice. We found that P. spinulosa had nearly doubled its host range by parasitizing at least six endemic rodent species in Australia. The other two introduced lice, P. serrata and Hoplopleura pacifica, however, have apparently failed to expand to any endemic rodents in Australia. Our analysis of mitochondrial rrnL gene sequences divided P. spinulosa into two genotypes (European vs Southeast Asian), which differ by 7.5%; both genotypes were introduced into Australia and then expanded their host ranges to include endemic rodents.
The earliest record of a European ship landing in Australia was in 1606, followed by British settlement in 1788. The expansion of P. spinulosa to at least six endemic rodent species in Australia has therefore occurred in the time frame of 200 to 400 years, which is extremely rapid relative to its host expansion to eight native rat species in Eurasia in ~ 16 million years since it diverged from P. serrata. The host expansion of P. spinulosa is remarkable for a blood-sucking louse and is in stark contrast to the absence of host expansion by P. serrata and H. pacifica. Comparison among these three introduced sucking lice indicated that both louse-specific factors and host-specific factors can contribute to the success or failure of host expansion.
历史上的欧洲探险和殖民活动导致四种啮齿动物从欧亚大陆引入澳大利亚大陆：褐家鼠、黑家鼠、太平洋鼠和小家鼠。这些啮齿动物的传播为它们共同引入的吸虱寄生和适应澳大利亚的特有啮齿动物创造了机会。
我们从澳大利亚七个博物馆的啮齿动物标本中收集吸虱。我们根据形态学鉴定出刺鼠虱，Polyplax spinulosa。我们对 P. spinulosa 标本的线粒体 cox1 和 rrnL 基因进行了测序，并构建了 rrnL 序列的系统发育树。
我们检查了 54 种 989 只啮齿动物标本，收集了 2111 只成年吸虱和 1064 只若虫吸虱。我们发现，P. spinulosa 通过寄生澳大利亚至少六种特有啮齿动物，其宿主范围几乎扩大了一倍。然而，另外两种引入的虱，P. serrata 和 Hoplopleura pacifica，显然未能扩展到澳大利亚的任何特有啮齿动物。我们对线粒体 rrnL 基因序列的分析将 P. spinulosa 分为两种基因型（欧洲型与东南亚型），它们之间的差异为 7.5%；这两种基因型都被引入澳大利亚，然后扩大了它们的宿主范围，包括特有啮齿动物。
最早记录的欧洲船只在澳大利亚登陆是在 1606 年，随后是 1788 年英国的定居。因此，P. spinulosa 扩展到澳大利亚至少六种特有啮齿动物的时间框架为 200 到 400 年，这与它从 P. serrata 分化以来在欧亚大陆扩展到 8 种本地鼠种的时间相比非常迅速。P. spinulosa 的宿主扩张对于吸血虱来说是显著的，与 P. serrata 和 H. pacifica 缺乏宿主扩张形成鲜明对比。对这三种引入的吸虱进行比较表明，虱特异性因素和宿主特异性因素都可以促成宿主扩张的成功或失败。
