Infrapopulation size and mate availability influence reproductive success of a parasitic plant

1. Aggregated distributions of parasite individuals across host individuals are nearly ubiquitous among parasitic taxa. The size and sex ratio of the population of one parasite species infecting a single host (hereafter “infrapopulation”) can influence parasite fitness through intraspecific competition, mate availability, and the ability to attract vectors for transmission of parasite propagules. Competition for both resources and for pollen and seed vector services may limit reproductive success (pollen receipt, fruit production, and seed dispersal) in large infrapopulations of parasitic plants, while mate limitation or reduced ability to attract vectors may limit this success in small infrapopulations. 2. Using a dioecious parasitic plant, desert mistletoe (Phoradendron californicum), we experimentally removed reproductive tissue from male parasites in whole infrapopulations to test for independent effects of infrapopulation size and within-host mate availability on female fitness. As...

1. 寄生类群中，寄生个体在宿主个体间的聚集分布几乎普遍存在。单个宿主所感染的某一寄生虫物种的种群规模与性比（以下简称“宿主内种群（infrapopulation）”），可通过种内竞争、可获得配偶的数量以及吸引媒介传播寄生虫传播体的能力，影响寄生虫的适合度。对于寄生植物而言，大型宿主内种群中，对资源、花粉及种子媒介服务的竞争，可能会限制其繁殖成效（包括花粉接收、果实产生与种子扩散）；而小型宿主内种群则可能因配偶限制或吸引媒介能力下降，同样制约繁殖成效。
2. 本研究以雌雄异株的寄生植物——沙漠槲寄生（*Phoradendron californicum*）为实验材料，通过移除完整宿主内种群中雄性寄生个体的生殖组织，以检验宿主内种群规模与宿主内可获得配偶数量对雌性适合度的独立影响。As...