How Does Circadian Rhythm Shape Host-Parasite Associations? A Comparative Study on Infection Patterns in Diurnal and Nocturnal Raptors

Infection patterns of parasites, including their prevalence, diversity and host specificity, can be impacted by many biological and environmental factors, but no study has focused on the circadian rhythms of vertebrate hosts, which may affect susceptibilities and encounter rates between hosts and vectors and further shape host-parasite associations. In this study, we focused on avian haemosporidians, a classical model in studies of host-parasite associations, and investigated the infection patterns in rescued raptors brought to the Beijing Raptor Rescue Center during 2007-2020. We first assessed the association between prevalence and host biotic traits; haemosporidian prevalence was higher in the nocturnal raptors than in the diurnal raptors, and the prevalence of Haemoproteus and Leucocytozoon in the nocturnal raptors was significantly higher than that in the diurnal raptors. Furthermore, we analysed the phylogenetic relationship and host-parasite network-level differences of haemosporidian parasites in diurnal and nocturnal raptors, and demonstrated that the lineages infecting the diurnal and nocturnal raptors were not clearly separated, but the nocturnal lifestyle led to a more specialized host-parasite network structure. These variations in host-parasite associations may be driven by different susceptibilities of the hosts and the diversity or abundance of vectors during the day and night. Our study provides new insight into host-parasite associations shaped by circadian rhythm and calls for more studies on the underlying mechanisms of parasite infection.

Automated summary

This study found that avian haemosporidians had higher prevalence in nocturnal raptors, and the host-parasite network structures differed between diurnal and nocturnal raptors. These variations may be driven by different susceptibilities of hosts and the diversity or abundance of vectors during the day and night.