Data from: Experimental evolution: assortative mating and sexual selection, independent of local adaptation, lead to reproductive isolation in the nematode Caenorhabditis remanei

Using experimental evolution, we investigated the contributions of
ecological divergence, sexual selection, and genetic drift to the
evolution of reproductive isolation in Caenorhabditis remanei. The
nematodes were reared on two different environments for 100 generations.
They were assayed for fitness on both environments after 30, 64, and 100
generations, and hybrid fitnesses were analyzed after 64 and 100
generations. Mating propensity within and between populations was also
analyzed. The design allowed us to determine whether local adaptation was
synchronous with pre- and post-zygotic reproductive isolation. Pre-zygotic
isolation evolved quickly but was unconnected with adaptation to the
divergent environments. Instead, pre-zygotic isolation was driven by mate
preferences favoring individuals from the same replicate population. A
bottleneck treatment, meant to enhance the opportunity for genetic drift,
had no effect on pre-zygotic isolation. Post-zygotic isolation occurred in
crosses where at least one population had a large fitness advantage in its
'home' environment. Taken together, our results suggest that
pre-zygotic isolation did not depend on drift or adaptation to divergent
environments, but instead resulted from differences in sexual interactions
within individual replicates. Furthermore, our results suggest that
post-zygotic isolation can occur between populations even when only one
population has greater fitness in its home environment.