Ishtiaq F, Guillaumot L, Clegg S M, Phillimore A B, Black R A, Owens I P F, Mundy N I, Sheldon B C
Edward Grey Institute, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
Mol Ecol. 2008 Oct;17(20):4545-55. doi: 10.1111/j.1365-294X.2008.03935.x.
The degree to which haematozoan parasites can exploit a range of vectors and hosts has both ecological and evolutionary implications for their transmission and biogeography. Here we explore the extent to which closely related mosquito species share the same or closely related haematozoan parasites, and examine the overlap in parasite lineages with those isolated from avian hosts, Zosterops species, sampled across the same study sites. Mosquito samples were collected and analysed (14 species, n = 804) from four islands in Vanuatu and the main island of New Caledonia. Using polymerase chain reaction, 15.5% (14/90) of pooled mosquito (thoracic) samples showed positive amplifications. Subsequent phylogenetic analysis of the cytochrome b gene identified four genetically distinct Plasmodium and two Haemoproteus lineages from these samples, five of which were identical to parasite lineages (n = 21) retrieved from the avian hosts. We found that three Plasmodium lineages differing by a maximum of 0.9% sequence divergence were recovered from different species and genera of mosquitoes and two Haemoproteus lineages differing by 4.6% sequence divergence were carried by 10 distantly related (11-21% divergent) mosquito species. These data suggest a lack of both cospeciation and invertebrate host conservatism. Without experimental demonstration of the transmission cycle, it is not possible to establish whether these mosquitoes are the biological vectors of isolated parasite lineages, reflecting a limitation of a purely polymerase chain reaction-based approach. Nonetheless, our results raise the possibility of a new transmission pathway and highlight extensive invertebrate host shifts in an insular mosquito-parasite system.
血寄生虫能够利用一系列媒介和宿主的程度，对其传播和生物地理学具有生态和进化意义。在这里，我们探讨了亲缘关系密切的蚊种共享相同或亲缘关系密切的血寄生虫的程度，并研究了与从同一研究地点采集的鸟类宿主（绣眼鸟属物种）分离的寄生虫谱系的重叠情况。从瓦努阿图的四个岛屿和新喀里多尼亚的主岛采集并分析了蚊子样本（14种，n = 804）。使用聚合酶链反应，15.5%（14/90）的合并蚊子（胸部）样本显示出阳性扩增。随后对细胞色素b基因进行的系统发育分析从这些样本中鉴定出四个遗传上不同的疟原虫谱系和两个血变原虫谱系，其中五个与从鸟类宿主中检索到的寄生虫谱系（n = 21）相同。我们发现，从不同蚊种和属中回收了三个序列差异最大为0.9%的疟原虫谱系，以及两个序列差异为4.6%的血变原虫谱系，由10种亲缘关系较远（差异11 - 21%）的蚊种携带。这些数据表明既缺乏共物种形成，也缺乏无脊椎动物宿主保守性。在没有对传播周期进行实验证明的情况下，无法确定这些蚊子是否是分离的寄生虫谱系的生物媒介，这反映了基于纯粹聚合酶链反应方法的局限性。尽管如此，我们的结果提出了一种新的传播途径的可能性，并突出了岛屿蚊 - 寄生虫系统中广泛的无脊椎动物宿主转移。
