Data from: Predator size divergence depends on community context

Body size is a multi-functional trait related to various fitness
components, but the relative importance of different selection pressures
are seldom resolved. In Carabus japonicus beetles, of which the larvae
exclusively prey on earthworms, adult body size is related to the
presence/absence of a larger congener and habitat temperature. In
sympatry, C. japonicus consistently exhibits smaller body size which is
effective for avoiding interspecific mating, but in allopatry, it shows
size variation unrelated to temperature. Here, we show that this
predator-size variation is attributed to prey-size variation, associated
with high phylogenetic diversity in earthworm communities. In allopatry,
the predator size was larger where larger prey occurred. Larger adult size
may have been selected because larger females produce larger larvae, which
can subdue larger prey. Thus, in the absence of a larger congener,
variation in prey body size had a pronounced effect on geographic body
size divergence in C. japonicus.