Data from: Inbreeding depression across a nutritional stress continuum

Many natural populations experience inbreeding and genetic drift as a
consequence of nonrandom mating or low population size. Furthermore, they
face environmental challenges that may interact synergistically with
deleterious consequences of increased homozygosity and further decrease
fitness. Most studies on inbreeding–environment (I-E) interactions use one
or two stress levels, whereby the resolution of the possible stress and
inbreeding depression interaction is low. Here we produced Drosophila
melanogaster replicate populations, maintained at three different
population sizes (10, 50 and a control size of 500) for 25 generations. A
nutritional stress gradient was imposed on the replicate populations by
exposing them to 11 different concentrations of yeast in the developmental
medium. We assessed the consequences of nutritional stress by scoring
egg-to-adult viability and body mass of emerged flies. We found: (1)
unequivocal evidence for I-E interactions in egg-to-adult viability and to
a lesser extent in dry body mass, with inbreeding depression being more
severe under higher levels of nutritional stress; (2) a steeper increase
in inbreeding depression for replicate populations of size 10 with
increasing nutritional stress than for replicate populations of size 50;
(3) a nonlinear norm of reaction between inbreeding depression and
nutritional stress; and (4) a faster increase in number of lethal
equivalents in replicate populations of size 10 compared with replicate
populations of size 50 with increasing nutritional stress levels. Our data
provide novel and strong evidence that deleterious fitness consequences of
I-E interactions are more pronounced at higher nutritional stress and at
higher inbreeding levels.