Parental care buffers against inbreeding depression in burying beetles

When relatives mate, their inbred offspring often suffer a reduction
in fitness-related traits known as “inbreeding depression.”
There is mounting evidence that inbreeding depression can be exacerbated
by environmental stresses such as starvation, predation,
parasitism, and competition. Parental care may play an important
role as a buffer against inbreeding depression in the offspring by
alleviating these environmental stresses. Here, we examine the
effect of parental care on the fitness costs of inbreeding in the
burying beetle Nicrophorus vespilloides, an insect with facultative
parental care. We used a 2 × 2 factorial design with the following
factors: (i) the presence or absence of a caring female parent during
larval development and (ii) inbred or outbred offspring. We
examined the joint influence of maternal care and inbreeding status
on fitness-related offspring traits to test the hypothesis that
maternal care improves the performance of inbred offspring more
than that of outbred offspring. Indeed, the female’s presence led
to a higher increase in larval survival in inbred than in outbred
broods. Receiving care at the larval stage also increased the lifespan
of inbred but not outbred adults, suggesting that the beneficial
buffering effects of maternal care can persist long after the
offspring have become independent. Our results show that parental
care has the potential to moderate the severity of inbreeding
depression, which in turn may favor inbreeding tolerance and influence
the evolution of mating systems and other inbreedingavoidance
mechanisms.