Data from: Phenotypic and genetic integration of personality and growth under competition in the sheepshead swordtail, Xiphophorus birchmanni

Competition for resources including food, physical space, and potential
mates is a fundamental ecological process shaping variation in individual
phenotype and fitness. The evolution of competitive ability, in particular
social dominance, depends on genetic (co)variation among traits causal
(e.g., behavior) or consequent (e.g., growth) to competitive outcomes. If
dominance is heritable, it will generate both direct and indirect genetic
effects (IGE) on resource-dependent traits. The latter are expected to
impose evolutionary constraint because winners necessarily gain resources
at the expense of losers. We varied competition in a population of
sheepshead swordtails, Xiphophorus birchmanni, to investigate effects on
behavior, size, growth, and survival. We then applied quantitative genetic
analyses to determine (i) whether competition leads to phenotypic and/or
genetic integration of behavior with life history and (ii) the potential
for IGE to constrain life history evolution. Size, growth, and survival
were reduced at high competition. Male dominance was repeatable and
dominant individuals show higher growth and survival. Additive genetic
contributions to phenotypic covariance were significant, with the G matrix
largely recapitulating phenotypic relationships. Social dominance has a
low but significant heritability and is strongly genetically correlated
with size and growth. Assuming causal dependence of growth on dominance,
hidden IGE will therefore reduce evolutionary potential.