Understanding parasite dispersal and distribution in island-colonising birds

引起传染病的寄生虫可以极大地改变宿主的种群动态。气候变化可能会加剧对人口的影响，因为宿主和寄生虫物种在追踪各自的生态位时会改变其活动范围，从而导致新的相互作用和疾病动态。尽管寄生虫传播和分布的生态和进化因素对于了解新发传染病、保护生物多样性和维持生态系统健康至关重要，但人们对它们的了解仍然很少。然而，大多数关于寄生虫传播的研究都集中在血液寄生虫上，例如禽疟疾，它依赖于节肢动物媒介进行传播，通常表现出专业的宿主关系。与消化道相关的寄生虫（“肠道寄生虫”）在其传播阶段随粪便释放并被消耗时感染未来宿主，从而可能感染广泛的宿主。不同的传播策略表明，鸟类血液和肠道寄生虫的扩散和感染模式可能存在差异，宿主迁移和扩散是寄生虫分布的关键。宿主的季节性迁移和长距离扩散都可能导致接触多种寄生虫区系，这种迁移也会产生高能量消耗，从而削弱免疫系统。因此，候鸟可能携带高度多样性的寄生虫，并携带高寄生虫负荷。同样，长距离传播者可能会逃脱，引入或获得寄生虫。长距离的扩散可能导致岛屿的殖民化。在岛屿殖民化，寄生虫多样性可能遵循islandisolation和面积平行于他们的hosts.A优秀的系统，同时研究每年的迁移，长距离传播，和岛屿寄生虫多样性和分布的影响islandiography原则银眼鸟（Zosterops lateralis），雀形目分布在澳大利亚和许多西南太平洋岛屿。他们包括部分移民、分散和完全定居的人口，他们通过在一系列时间尺度上的分散在岛屿上殖民（几百到几十万年，允许寄生虫多样性的变化被校准。对于我的博士学位，我将与伦敦的自然历史博物馆和自然博物馆（可能作为CASE合作伙伴关系）合作，研究寄生虫在岛屿上的传播和分布。陆栖鸟类我将采用最先进的元条形码和高通量测序（HTS）方法，从粪便和血液中的多种寄生虫感染（所有非破坏性采样）中检测整个肠道寄生虫群落。此外，我还将从分布在各地的银眼血液样本中提取原始全基因组序列（WGS），以提取寄生虫读数。多种寄生虫感染在自然界中普遍存在，但大多数研究集中在单一寄生虫系统。我的研究将提供一个罕见的“寄生虫群落”方法的例子，并提高我们对不断变化的寄生虫分布和传播模式的理解。

Parasites that cause infectious disease can drastically alter host population dynamics. Population impacts may be exacerbated by climate change as host and parasite species respond by shifting their ranges as they track their respective ecological niches, leading to novel interactions and disease dynamics. The ecological and evolutionary factors underpinning parasite dispersal and distribution remain poorly understood despite their critical importance for understanding emerging infectious diseases, protecting biodiversity and maintaining ecosystem health.Birds are increasingly recognised as important parasite dispersers. Yet, most research on parasite dispersal focusses on blood parasites, such as avian malaria, which rely on arthropod vectors for transmission and typically exhibit specialist host relationships. Parasites associated with the digestive tract ('gut parasites') infect future hosts when their transmission stages are released with faeces and consumed, potentially enabling the infection of a wide range of hosts. The contrasting transmission strategies suggest there may be variation in diversities and infection patterns of blood and gut parasites in birds.Host migration and dispersal are key to parasite distribution. Both seasonal migration and long-distance dispersal of hosts can result in exposure to multiple parasite faunas, such movements also havehigh energetic costs that can weaken the immune system. Therefore, migratory birds may transport a high diversity of parasites and carry high parasite loads. Similarly, long-distance dispersers may escape, introduce or gain parasites. Long-distance dispersal can lead to colonisation of islands. During island colonisation, parasite diversity may follow island biogeography principles related to islandisolation and area in parallel with their hosts.An excellent system to simultaneously study the impact of annual migration, long-distance dispersal, and island biogeography on parasite diversity and distribution is presented by the silvereye bird (Zosterops lateralis), a passerine distributed in Australia and numerous south-west Pacific Islands. They include partial migrant, dispersive and totally sedentary populations, and they have colonised islands via dispersal over a range of timescales (hundreds to hundreds of thousands of years, allowing changes in parasite diversity to be calibrated.For my PhD, I will collaborate with the Natural History Museum in London and Nature Metrics (potentially as a CASE partnership) to study parasite dispersal and distributions in island-dwelling terrestrial birds. I will employ cutting edge metabarcoding and High-Throughput Sequencing (HTS) methods to characterise whole gut parasite communities from faeces and multiple parasite infections from blood (all non-destructively sampled). Additionally, I will mine raw Whole Genome Sequences (WGS) already available from silvereye blood samples across their distribution to extract parasite reads. Multiple parasite infections are ubiquitous in nature, yet most research focuses on single parasite systems. My study will provide a rare example of a 'parasite community' approach and improve our understanding of changing parasite distributions and dispersal patterns.