EcoHealth Alliance, New York, NY 10001, USA.
Parasit Vectors. 2013 Aug 8;6:231. doi: 10.1186/1756-3305-6-231.
Population-level studies of parasites have the potential to elucidate patterns of host movement and cross-species interactions that are not evident from host genealogy alone. Bat flies are obligate and generally host-specific blood-feeding parasites of bats. Old-World flies in the family Nycteribiidae are entirely wingless and depend on their hosts for long-distance dispersal; their population genetics has been unstudied to date.
We collected a total of 125 bat flies from three Pteropus species (Pteropus vampyrus, P. hypomelanus, and P. lylei) from eight localities in Malaysia, Cambodia, and Vietnam. We identified specimens morphologically and then sequenced three mitochondrial DNA gene fragments (CoI, CoII, cytB; 1744 basepairs total) from a subset of 45 bat flies. We measured genetic diversity, molecular variance, and population genetic subdivision (FST), and used phylogenetic and haplotype network analyses to quantify parasite genetic structure across host species and localities.
All flies were identified as Cyclopodia horsfieldi with the exception of two individuals of Eucampsipoda sundaica. Low levels of population genetic structure were detected between populations of Cyclopodia horsfieldi from across a wide geographic range (~1000 km), and tests for isolation by distance were rejected. AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations. Pairwise FST values from flies collected from island populations of Pteropus hypomelanus in East and West Peninsular Malaysia supported predictions based on previous studies of host genetic structure.
The lack of population genetic structure and morphological variation observed in Cyclopodia horsfieldi is most likely due to frequent contact between flying fox species and subsequent high levels of parasite gene flow. Specifically, we suggest that Pteropus vampyrus may facilitate movement of bat flies between the three Pteropus species in the region. We demonstrate the utility of parasite genetics as an additional layer of information to measure host movement and interspecific host contact. These approaches may have wide implications for understanding zoonotic, epizootic, and enzootic disease dynamics. Bat flies may play a role as vectors of disease in bats, and their competence as vectors of bacterial and/or viral pathogens is in need of further investigation.
从种群水平研究寄生虫，有可能阐明宿主移动和跨物种相互作用的模式，而这些模式单凭宿主的系统发育并不能明显看出。蝙蝠蝇是蝙蝠的专性寄生血蝇，通常具有宿主特异性。旧世界的吸血蝇科 Nycteribiidae 完全没有翅膀，依赖宿主进行长距离传播；迄今为止，它们的种群遗传学尚未得到研究。
我们从马来西亚、柬埔寨和越南的 8 个地点共采集了三种果蝠（大长舌果蝠、马来大狐蝠和西里伯斯狐蝠）的 125 只蝙蝠蝇。我们通过形态学鉴定标本，然后从 45 只蝙蝠蝇中随机选取了 3 个线粒体 DNA 基因片段（CoI、CoII、cytB；总 1744 个碱基对）进行测序。我们测量了遗传多样性、分子方差和种群遗传分化（FST），并使用系统发育和单倍型网络分析来量化宿主物种和地点之间寄生虫的遗传结构。
除了 2 只巽他食虫虻外，所有蝇类均被鉴定为霍氏角蝇。在地理范围广泛（约 1000 公里）的角蝇种群之间检测到种群遗传结构水平较低，且拒绝了距离隔离检验。AMOVA 结果支持缺乏地理和宿主特异性的种群结构，分子方差主要在种群内分离。从东马和西马半岛的马来大狐蝠岛屿种群中采集的蝇类的成对 FST 值支持了先前对宿主遗传结构研究的预测。
角蝇中观察到的种群遗传结构和形态变异的缺乏很可能是由于果蝠物种之间频繁接触以及随后的寄生虫基因流动水平较高所致。具体来说，我们认为吸血蝠可能促进了该地区三种果蝠之间的蝙蝠蝇移动。我们证明了寄生虫遗传学作为衡量宿主移动和种间宿主接触的附加信息层的效用。这些方法可能对理解人畜共患病、动物流行病和内动物病的动态具有广泛的意义。蝙蝠蝇可能在蝙蝠中扮演疾病传播媒介的角色，需要进一步研究它们作为细菌和/或病毒病原体传播媒介的能力。
