Parental care buffers against inbreeding depression in burying beetles

Abstract

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.parental care | environmental stress | fitness | inbreeding depression | inbreeding tolerance

Inbreeding parents should invest more resources in fewer offspring

“…For example, Pilakouta et al . [39] quantified the fitness of inbred and outbred burying beetle ( Nicrophorus vespilloides ) offspring in the presence and absence of maternal care, finding that maternal care increased survival of inbred offspring relatively more than survival of outbred offspring (see also [40]). Interpreting care as a component of PI, this result concurs with the assumption that PI can reduce ID.…”

Fitness traits of Drosophila melanogaster (Diptera: Drosophilidae) after long-term laboratory rearing on different diets

“…Phenotypic plasticity, defi ned as "the ability of individual genotypes to produce different phenotypes when exposed to different environmental conditions" (Pigliucci et al, 2006) can infl uence fi tness directly, if the ability to be plastic is adaptive (Sultan & Spencer, 2002;Crispo, 2008;Stomp et al, 2008), or indirectly, if the plastic response results in the development of an adaptive phenotype (Via et al, 1995). During their lifetime, individuals may adapt by means of developmental plasticity, since they may experience environments in early life that are associated with particular conditions they will experience later in life (Monaghan, 2008;Pilakouta et al, 2015). Selection for feeding on different foods can result in trade-offs associated with the adaptation, which could be manifested in terms of larval development and survival (Kolss et al, 2009).…”

Maternal effects alter the severity of inbreeding depression in the offspring

“…Moreover, we have previously shown that there is severe inbreeding depression in this species, with respect to survival at the larval and pupal stages, as well as adult lifespan [12,21,22]. We have also shown that inbreeding depression in the offspring is less severe when the mother is present than when she is removed [12]. Given that small females provide less post-hatching care than large females [16,17], we hypothesized that inbred offspring would suffer a greater reduction in fitness (compared with outbred offspring) if they had a small mother than if they had a large mother.…”

“…Earlier work has proposed that this variation may be partly attributed to differences in the physical or social environment [7][8][9]. Environmental stresses, such as starvation and competition, tend to exacerbate inbreeding depression [8,10], whereas benign conditions may moderate inbreeding depression [11,12].…”