Data from: Multiple biological mechanisms result in correlations between pre- and post-mating traits that differ among versus within individuals and genotypes

Reproductive traits involved in mate acquisition (pre-mating traits) are
predicted to covary with those involved in fertilization success
(post-mating traits). Variation in male quality may give rise to positive,
and resource allocation trade-offs to negative, covariances between pre-
and post-mating traits. Empirical studies have yielded mixed results.
Progress is hampered as researchers often fail to appreciate that
mentioned biological mechanisms can act simultaneously but at different
hierarchical levels of biological variation: genetic correlations may, for
example, be negative due to genetic trade-offs but environmental
correlations instead positive due to individual variation in resource
acquisition. We measured pre-mating (aggression, body weight) and
post-mating (ejaculate size) reproductive traits in a pedigreed population
of southern field crickets (Gryllus bimaculatus). To create environmental
variation, crickets were raised on either a low or a high nymphal density
treatment. We estimated genetic and environmental sources of correlations
between pre- and post-mating traits. We found positive genetic
correlations between pre- and post-mating traits, implying the existence
of genetic variation in male quality. Over repeated trials of the same
individual (testing order), positive changes in one trait were matched
with negative changes in other traits, suggesting energy allocating
trade-offs within individuals among days. These findings demonstrate the
need for research on pre- and post-mating traits to consider the
hierarchical structure of trait correlations. Only by doing so was our
study able to conclude that multiple mechanisms jointly shape phenotypic
associations between pre- and post-mating traits in crickets.