Data from: The evolution of male-biased sexual size dimorphism is associated with increased body size plasticity in males

1.Sexual size dimorphism (SSD) can vary drastically across environments,
demonstrating pronounced sex-specific plasticity. In insects, females are
usually the larger and more plastic sex. However, the shortage of taxa
with male-biased SSD hampers the assessment of whether the greater
plasticity in females is driven by selection on size or represents an
effect of the female reproductive role. Here we specifically address the
role of sex-specific plasticity of body size in the evolution of SSD
reversals to disentangle sex and size effects. 2.We first investigate
sex-specific body size plasticity in Sepsis punctum and S. neocynipsea as
two independent cases of intraspecific SSD reversals in sepsid flies. In
both species, directional variation in SSD between populations is driven
by stronger sexual selection on male size. Using controlled laboratory
breeding, we find evidence for sex-specific plasticity and increased
condition dependence of male size in populations with male-biased SSD, but
not of female size in populations with female-biased SSD, indicating no
adaptive canalization of female size. 3.To extend the comparative scope,
we next estimate sex-specific body size plasticity in eight additional fly
species that differ in the direction of SSD under laboratory conditions.
In all species with male-biased SSD we find males to be the more plastic
sex, while this was only rarely the case in species with female-biased
SSD, thus suggesting a more general trend in Diptera. 4.To examine the
generality of this pattern in holometabolous insects, we combine our data
with data from the literature in a meta-analysis. Again, male body size
tends to be more plastic than female size when males are the larger sex,
though female size is now also generally more plastic when females are
larger. 5.Our findings indicate that primarily selection on size, rather
than the reproductive role per se, drives the evolution of sex-specific
body size plasticity. However, sepsid flies, and possibly Diptera in
general, show a clear sexual asymmetry with greater male than female
plasticity related to SSD, likely driven by strong sexual selection on
males. Although further research controlling for phylogenetic and
ecological confounding effects is needed, our findings are congruent with
theory in suggesting that condition dependence plays a pivotal role in the
evolution of sexual size dimorphism.