Avian brood parasitism and ectoparasite richness – scale-dependent diversity interactions in a three-level host-parasite system

Brood parasitic birds, their foster species and their ectoparasites form a complex co-evolving system composed of three hierarchical levels. However, effects of hosts’ brood parasitic life-style on the evolution of their louse (Phthiraptera: Amblycera, Ischnocera) lineages have never been tested. We present two phylogenetic analyses of ectoparasite richness of brood parasitic clades. Our hypothesis was that brood parasitic life-style affects louse richness negatively across all avian clades due to the lack of vertical transmission routes. Then, narrowing our scope to brood parasitic cuckoos, we explored macroevolutionary factors responsible for the variability of their louse richness. Our results show that taxonomic richness of lice is lower on brood parasitic clades than on their non-parasitic sister clades. On the other hand, we found a positive co-variation between the richness of cuckoos’ Ischnoceran lice and the number of their foster species, possibly due to the complex and dynami...