Data from: Mating environments mediate the evolution of behavioral isolation during ecological speciation

The evolution of behavioral isolation is often the first step towards
speciation. While past studies show that behavioral isolation will
sometimes evolve as a by-product of divergent ecological selection, we
lack a more nuanced understanding of factors that may promote or hamper
its evolution. The environment in which mating occurs may be important in
mediating whether behavioral isolation evolves for two reasons. Ecological
speciation could occur as a direct outcome of different sexual
interactions being favored in different mating environments.
Alternatively, mating environments may vary in the constraint they impose
on traits underlying mating interactions, such that populations evolving
in a ‘constraining’ mating environment would be less likely to evolve
behavioral isolation than populations evolving in a less constraining
mating environment. In the latter, mating environment is not the direct
cause of behavioral isolation but rather permits its evolution only if
other drivers are present. We test these ideas with a set of 28
experimental fly populations, each of which evolved under one of two
mating environments and one of two larval environments. Counter to the
prediction of ecological speciation by mating environment, behavioral
isolation was not maximal between populations evolved in different mating
environments. Nonetheless, mating environment was an important factor as
behavioral isolation evolved among populations from one mating environment
but not among populations from the other. Though one mating environment
was conducive to the evolution of behavioral isolation, it was not
sufficient: assortative mating only evolved between populations adapting
to different larval environments within that mating environment,
indicating a role for ecological speciation. Intriguingly, the mating
environment that promoted behavioral isolation is characterized by less
sexual conflict compared to the other mating environment. Our results
suggest that mating environments plays a key role in mediating ecological
speciation via other axes of divergent selection.