Haemosporidian infection and co-infection affect host survival and reproduction in wild populations of great tits

Theoretical studies predict that parasitic infection may impact host longevity and ultimately modify the trade-off between reproduction and survival. Indeed, a host may adjust its energy allocation in current reproduction to balance the negative effects of parasitism on its survival prospects. However, very few empirical studies tested this prediction. Avian haemosporidian parasites provide an excellent opportunity to assess the influence of parasitic infection on both host survival and reproduction. They are represented by three main genera (Plasmodium, Haemoproteus and Leucocytozoon) and are highly prevalent in many bird populations. Here we provide the first known long-term field study (12 years) to explore the effects of haemosporidian parasite infection and co-infection on fitness in two populations of great tits (Parus major), using a multistate modelling framework. We found that while co-infection decreased survival probability, both infection and co-infection increased reproduct...理论研究预测，寄生虫感染可能会影响宿主寿命，并最终改变繁殖与生存之间的权衡关系。事实上，宿主可通过调整当前繁殖过程中的能量分配，以平衡寄生虫感染对其生存前景造成的负面影响。然而，目前验证这一理论预测的实证研究仍较为匮乏。禽血孢子虫寄生虫（Avian haemosporidian parasites）为评估寄生虫感染对宿主生存与繁殖的影响提供了极佳的研究契机。该类寄生虫包含3个主要属：疟原虫属（Plasmodium）、血变虫属（Haemoproteus）以及住白细胞虫属（Leucocytozoon），在众多鸟类种群中感染率极高。本研究采用多状态建模框架，对两个大山雀（Parus major）种群开展了目前已知的首个为期12年的长期野外调查，以探究禽血孢子虫感染与混合感染对宿主适合度的影响。研究发现，尽管混合感染会降低宿主的生存概率，但无论是单一感染还是混合感染，均能提升繁殖……