Data from: Apparent vector-mediated parent-to-offspring transmission in an avian malaria-like parasite

Parasite transmission strategies strongly impact host–parasite
co-evolution and virulence. However, studies of vector-borne parasites
such as avian malaria have neglected the potential effects of host
relatedness on the exchange of parasites. To test whether extended
parental care in the presence of vectors increases the probability of
transmission from parents to offspring, we used high-throughput sequencing
to develop microsatellites for malaria-like Leucocytozoon parasites of a
wild raptor population. We show that host siblings carry genetically more
similar parasites than unrelated chicks both within and across years.
Moreover, chicks of mothers of the same plumage morph carried more similar
parasites than nestlings whose mothers were of different morphs,
consistent with matrilineal transmission of morph-specific parasite
strains. Ours is the first evidence of an association between host
relatedness and parasite genetic similarity, consistent with
vector-mediated parent-to-offspring transmission. The conditions for such
‘quasi-vertical’ transmission may be common and could suppress the
evolution of pathogen virulence.