The reliability of environmental cues shapes learning and selection against deleterious alleles in seed beetles

Behavioural plasticity can play a key role in evolution by either
facilitating or impeding genetic adaptation. The latter occurs when
behaviours mitigate selection pressures that otherwise would target
associated traits. Therefore, environments that facilitate adaptive
behavioural plasticity could relax the strength of natural selection, but
experimental evidence for this prediction remains scarce. Here, we first
demonstrate that maternal care in the beetle Callosobruchus maculatus is
dependent on reliable environmental cues that allow females to reduce
larval competition via learning and informed oviposition choices. We show
that this facilitation of maternal care relaxes selection against
deleterious alleles in offspring. We further find that mothers of low
genetic quality generally provide poorer care. However, when receiving
reliable environmental cues, the increased opportunity for learning
reduced genetic differences in maternal care, further relaxing selection
against deleterious alleles. We use our data to illustrate how the
identified link between learning of maternal care and the strength of
natural selection can impact indirect genetic effects between mothers and
offspring and the accumulation of cryptic genetic loads in populations
inhabiting environments that differ in their predictability.