The drivers of avian haemosporidian prevalence in tropical lowland
forest of New Guinea in three dimensions
Abstract
Haemosporidians are among the most common parasites in birds and often
impact negatively host fitness and consequently can affect entire host
populations. It is therefore important to determine what factors
influence parasite prevalence, particularly if they are caused by
anthropogenic activities. Here we explore the effect of temperature,
forest cover, and proximity to anthropogenic disturbance on
haemosporidian prevalence and host-parasite networks on a horizontal
spatial scale, comparing four fragmented forest patches and five
localities within a continuous forest in Papua New Guinea. We find that
the majority of Haemosporidian infections are caused by the genus
Haemoproteus and that avian-haemosporidian networks are more specialized
in continuous forests. At the community level, only forest cover was
negatively associated with Haemoproteus infections, while abiotic and
anthropogenic effects on parasite prevalence differed between bird
species. We further tested if prevalence and host-parasite networks
differed between the canopy and the understorey (vertical
stratification) and found significantly higher Haemoproteus prevalence
levels in the canopy, and the opposite trend for Plasmodium prevalence.
This implies that birds experience distinct parasite pressures depending
on the stratum they inhabit, likely driven by differences in vector
communities. These three-dimensional analyses of avian-haemosporidians
at horizontal and vertical scales provides a deeper understanding of the
environmental factors driving haemosporidian prevalence in tropical
lowland forests of New Guinea. Collectively, our results suggest that
the effect of abiotic variables on haemosporidian infections are species
specific, and that factors influencing community-level infections are
primarily driven by host community composition.