Data from: The contribution of mutation to variation in temperature-dependent sprint speed in zebrafish, Danio rerio

The contribution of new mutations to phenotypic variation, and the
consequences of this variation for individual fitness, are fundamental
concepts for understanding genetic variation and adaptation. Here, we
investigated how mutation influenced variation in a complex trait in
zebrafish, Danio rerio. Typical of many ecologically relevant traits in
ectotherms, swimming speed in fish is temperature-dependent, with evidence
of adaptive evolution of thermal performance. We chemically induced novel
germline point mutations in males and measured sprint speed in their sons
at six temperatures (between 16°C and 34°C). Heterozygous mutational
effects on speed were strongly positively correlated among temperatures,
resulting in statistical support for only a single axis of mutational
variation, reflecting temperature-independent variation in speed
(faster-slower mode). These results suggest pleiotropic effects on speed
across different temperatures, however, spurious correlations arise via
linkage, or heterogeneity in mutation number when mutations have
consistent directional effects on each trait. Here, mutation did not
change mean speed, indicating no directional bias in mutational effects.
The results contribute to emerging evidence that mutations may
predominantly have synergistic cross-environment effects, in contrast to
conditionally neutral or antagonistic effects which underpin thermal
adaptation. We discuss several aspects of experimental design that may
affect resolution of mutations with non-synergistic effects.