Data from: Can variation in standard metabolic rate explain context-dependent performance of farmed salmon offspring?

Escaped farmed Atlantic salmon interbreed with wild Atlantic salmon,
leaving offspring that often have lower success in nature than pure wild
salmon. On top of this, presence of farmed salmon descendants can impair
production of wild type recruits. We hypothesize that both these effects
connect with farmed salmon having acquired higher standard metabolic rates
(SMR, the energetic cost of self-maintenance) during domestication.
Furthermore, fitness related advantages of phenotypic traits associated
with both high SMR and farmed salmon (e.g. social dominance) depend on
environmental conditions, such as food availability. We hypothesize that
farmed offspring have an advantage at high food availability due to e.g.
dominance behavior but suffer increased risks of starvation when food is
scarce because this behavior is energy-demanding. To test these
hypotheses, we first compare embryo SMR of pure farmed, farmed-wild
hybrids and pure wild offspring. Next, we test early life performance (in
terms of survival and growth) of hybrids relative to that of their wild
half-siblings, as well as their competitive abilities, in semi-natural
conditions of high and low food availability. Finally, we test how SMR
affects early life performance at high and low food availability. We find
inconclusive support for the hypothesis that domestication has induced
increased SMR. Further, wild and hybrid juveniles had similar survival and
growth in the semi-natural streams. Yet, the presence of hybrids led to
decreased survival of their wild half-siblings. Contrary to our hypothesis
about context-dependency, these effects were not modified by food
availability. However, wild juveniles with high SMR had decreased survival
when food was scarce, but there was no such effect at high food
availability. This study provides further proof that farmed salmon
introgression may compromise the viability of wild salmon populations. We
cannot, however, conclude that this is connected to alterations in the
metabolic phenotype of farmed salmon.