Data from: Population genetic structure of the tree-hole tick Ixodes arboricola (Acari: Ixodidae) at different spatial scales

The endophilic tick Ixodes arboricola infests cavity-nesting birds, and
its dispersal strongly depends on the movements of its host. Population
genetic structure of I. arboricola was studied with seven polymorphic
microsatellite markers. We collected 268 ticks from 76 nest boxes in four
woodlots near Antwerp, Belgium. These nest boxes are mainly used by the
principal hosts of I. arboricola, the great tit Parus major and the blue
tit Cyanistes caeruleus. As these birds typically return to the same
cavity for roosting or breeding, ticks within nest boxes were expected to
be highly related, and tick populations were expected to be spatially
structured among woodlots and among nest boxes within woodlots. In line
with the expectations, genetic population structure was found among
woodlots and among nest boxes within woodlots. Surprisingly, there was
considerable genetic variation among ticks within nest boxes. This could
be explained by continuous gene flow from ticks from nearby tree holes,
yet this remains to be tested. A pairwise relatedness analysis conducted
for all pairs of ticks within nest boxes showed that relatedness among
larvae was much higher than among later instars, which suggests that
larvae are the most important instar for tick dispersal. Overall, tick
populations at the studied spatial scale are not as differentiated as
predicted, which may influence the scale at which host–parasite evolution
occurs.