Drosophila serrata mutation accumulation lines: Phenotypic data on survival following infection with Drosophila C virus and reproduction

The impact of selection on host immune function genes has been widely
documented. However, it remains essentially unknown how mutation
influences the quantitative immune traits that selection acts on. Applying
a classical mutation accumulation (MA) experimental design in Drosophila
serrata, we found the mutational variation in susceptibility (median time
of death, LT50) to Drosophila C virus (DCV) was of similar magnitude to
that reported for intrinsic survival traits. Mean LT50 did not change as
mutations accumulated, suggesting no directional bias in mutational
effects. Maintenance of genetic variance in immune function is
hypothesised to be influenced by pleiotropic effects on immunity and other
traits that contribute to fitness. To investigate this, we assayed female
reproductive output for a subset of MA lines with relatively long or short
survival times under DCV infection. Longer survival time tended to be
associated with lower reproductive output, suggesting that mutations
affecting susceptibility to DCV had pleiotropic effects on investment in
reproductive fitness. Further studies are needed to uncover the general
patterns of mutational effect on immune responses and other fitness
traits, and to determine how selection might typically act on new
mutations via their direct and pleiotropic effects.