The human head louse (Pediculus humanus capitis) is an obligate
ectoparasite of humans and has the potential to uncover aspects of human
history that cannot be directly inferred from genetic data derived from
humans. Previous studies have shown that global louse populations
exhibit restricted patterns of genetic variation. However, these studies
were restricted both genetically and lacked a global sampling. With the
aim of capturing the genetic diversity of head louse populations from
around the world, we generated whole genome sequences of human head lice
from 43 countries, spanning five continents and Oceania, to determine if
louse nuclear diversity mirrors its mitochondrial haplotypes or if
population genetic structure, genetic diversity, and population
connectivity are associated with geographical regions or host behavior.
Here we show that there are five nuclear genetic clusters that are
associated with large geographical regions, either at continental or
intercontinental levels. High genetic variation was found between
African and non-African individuals and the highest genetic diversity
was found in samples from sub-Saharan Africa, similar to that of humans.
Unlike the mitochondrial clades examined in previous studies, nuclear
genetic clusters of lice examined here are highly structured based on
geography (continentally and major regions within continents). Results
from our genome analyses revealed that host-mediated global dispersal as
the likely primary process in shaping diversity and maintaining genetic
population boundaries within the nuclear genome of the human head louse.