Experimental design
We used a highly inbred (at least 20 generations of inbreeding) strain
of K. marmoratus (R (Ellisonet al. 2012a)) kept under standard laboratory conditions (25-27
°C, 16-18‰, 12h light: 12h dark photoperiod). For the parental
generation, eggs from five fish of similar size and age were reared
individually until hatching, when larvae were transferred to tanks with
either enriched environment (shelter and plants, n=14) or poor
environment (identical except no enrichment, n=13), where they were kept
for 10 months (Berbel-Filho et al.2019).
To standardise potential age-related parental effects, eggs were only
collected from parents of similar age (7-10 months). The offspring of
five genetically inbred parents (three from enriched and two from poor
environments) were set up following a factorial design with matched or
mismatched parent-offspring environments (Fig. S1; Table S1). The
offspring consisted of 15 mismatched individuals (seven poor to enriched
and eight enriched to poor), and 13 matched individuals (eight enriched
to enriched and seven poor to poor).