Data from: Antagonistic coevolution accelerates the evolution of reproductive isolation in Tribolium castaneum

The evolution of reproductive isolation among populations is often the
result of selective forces. Among those, parasites exert strong selection
on host populations and can thus also potentially drive reproductive
isolation. This hypothesis has yet to be explicitly tested and, here, we
set up a multigenerational coevolution experiment to explore this
possibility. Five lines of Tribolium castaneum were allowed to coevolve
with their natural parasite, Nosema whitei; five paired lines of identical
origin were maintained in the absence of parasites. After 17 generations,
we measured resistance within and reproductive isolation between all
lines. Host lines from the coevolution treatment had considerable higher
levels of resistance against N. whitei than their paired host lines which
were maintained in the absence of parasites. Reproductive isolation was
greater in the coevolved selection regime and correlated with phenotypic
differentiation in parasite resistance between coevolved host lines. This
suggests the presence of a selection-driven genetic correlation between
offspring number and resistance. Our results show that parasites can be a
driving force in the evolution of reproductive isolation, and thus
potentially speciation.