Data from: Specialized avian Haemosporida trade reduced host breadth for increased prevalence

Parasite specialization on one or a few host species leads to a reduction in the total number of available host individuals, which may decrease transmission. However, specialists are thought to be able to compensate by increased prevalence in the host population and increased success in each individual host. Here, we use variation in host breadth among a community of avian Haemosporida to investigate consequences of generalist and specialist strategies on prevalence across hosts. We show that specialist parasites are more prevalent than generalist parasites in host populations that are shared between them. Moreover, the total number of infections of generalist and specialist parasites within the study area did not vary significantly with host breadth. This suggests that specialists can infect a similar number of host individuals as generalists, thus compensating for a reduction in host availability by achieving higher prevalence in a single host species. Specialist parasites also tended to infect older hosts, whereas infections by generalists were biased towards younger hosts. We suggest that this reflects different abilities of generalists and specialists to persist in hosts following infection. Higher abundance and increased persistence in hosts suggest that specialists are more effective parasites than generalists, supporting the existence of a trade-off between host breadth and average host use among these parasites.寄生物对单一种或少数几种宿主物种的特化，会导致可利用宿主个体总数下降，进而可能降低其传播效率。不过现有研究认为，特化型寄生物可通过提升在宿主种群中的感染率，以及提升在单个宿主个体内的侵染成功率来弥补这一缺陷。本研究借助鸟类血孢子虫目（Haemosporida）类群群落中宿主广度（host breadth）的差异，探究泛化型与特化型寄生策略对跨宿主感染率的影响。研究结果显示，在两类寄生物共享的宿主种群中，特化型寄生物的感染率高于泛化型寄生物。此外，研究区域内泛化型与特化型寄生物的总感染数并未随宿主广度发生显著变化。这表明特化型寄生物可感染的宿主个体总数与泛化型寄生物相当，因此它们可通过提升单一宿主物种内的感染率，弥补宿主可利用性降低的不足。特化型寄生物还更倾向于侵染老龄宿主，而泛化型寄生物的感染则偏向幼龄宿主。我们推测，这一现象反映了泛化型与特化型寄生物在侵染宿主后持续存活的能力差异。更高的种群丰度与更强的宿主内存续能力，表明特化型寄生物的寄生效能优于泛化型寄生物，这支持了这类寄生物在宿主广度与平均宿主利用效率之间存在权衡（trade-off）的假说。