Abstract:
The nematode worm Spirocerca lupi has a cosmopolitan distribution and can cause the death
of its final canid host, typically dogs. While its life cycle, which involves a coprophagous
beetle intermediate host, a number of non-obligatory vertebrate paratenic hosts and a canid
final host, is well understood, surprisingly little is known about its transmission dynamics
and population genetic structure. Here we sequenced cox1 to quantify genetic variation
and the factors that limit gene flow in a 300 km2 area in South Africa. Three quarters of
the genetic variation, was explained by differences between worms from the same host,
whereas a quarter of the variation was explained by differences between worms from different
hosts. With the help of a newly derived model we conclude that while the offspring
from different infrapopulations mixes fairly frequently in new hosts, the level of admixture
is not enough to homogenize the parasite populations among dogs. Small infrapopulation
sizes along with clumped transmission may also result in members of infrapopulations
being closely related.
