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A lack of parental care is generally assumed to entail substantial fitness costs for offspring that ultimately select for the maintenance of family life across generations. However, it is unknown whether these costs arise when parental care is facultative, thus questioning their fundamental importance in the early evolution of family life. Here, we investigated the short-term, long-term and transgenerational effects of maternal loss in the European earwig Forficula auricularia, an insect with facultative post-hatching maternal care. We showed that maternal loss did not influence the developmental time and survival rate of juveniles, but surprisingly yielded adults of larger body and forceps size, two traits associated with fitness benefits. In a cross-breeding/cross-fostering experiment, we then demonstrated that maternal loss impaired the expression of maternal care in adult offspring. Interestingly, the resulting transgenerational costs were not only mediated by the early-life experience of tending mothers, but also by inherited, parent-of-origin-specific effects expressed in juveniles. Orphaned females abandoned their juveniles for longer and fed them less than maternally-tended females, while foster mothers defended juveniles of orphaned females less well than juveniles of maternally-tended females. Overall, these findings reveal the key importance of transgenerational effects in the early evolution of family life.

Kin competition often reduces – and sometimes entirely negates – the benefits of cooperation among family members. Surprisingly, the impact of kin competition on the fitness effects of family life only received close scrutiny in studies on sibling rivalry, whereas the possibility of parent–offspring competition has attracted much less attention. As a consequence, it remains unclear whether and how parent–offspring competition could have affected the early evolution of parental care and family life. Here, we examined the occurrence and consequences of parent–offspring competition over food access in the European earwig Forficula auricularia, an insect with facultative family life reminiscent of an ancestral state. Specifically, we (1) raised earwig offspring under food limitation either together with or without their mother, and (2) tested whether and how the — potentially competitive — weight gains of mothers and offspring during family life affected the offsprings' survival rate and morphology, and the future reproductive investment of their mother. In line with the occurrence of parent–offspring competition, we showed that high maternal weight gains during family life reduced the survival prospects of maternally tended offspring, while they increased the mothers' investment into the production of a second clutch (but not the body size of the surviving offspring). Conversely, high offspring weight gains generally increased the offsprings' survival, but did so to a larger extent when they were together with their mother. Intriguingly, mothers that had exhibited a low initial weight showed especially high weight gains. Overall, our results demonstrate that maternal presence under food restriction triggered a local competition between mothers and their offspring. This competition limited offspring survival, but allowed mothers to increase their investment into future reproduction and/or to maintain their current body condition. On a general level, our findings reveal that parent–offspring competition can counteract the benefits of (facultative) parental care, and may thus impede the evolution of family life in resource‐poor environments. A plain language summary is available for this article. Plain Language Summary

In several primates, the presence of mothers affects the growth, survival and reproduction of their offspring, but similar effects have not yet been demonstrated in ungulates. Here, we investigate the effects of the mother's presence in a population of red deer (Cervus elaphus) on the Isle of Rum, Scotland, which is the subject of a long-term, individual-based study. We compared measures of performance including antler growth in young males and age at first reproduction in females and survival of deer with mothers still alive against those that have lost their mothers (orphans). We show that orphaning both before and after weaning increases the risk of a natural death for both sexes. For males, no maternal benefit was detectable past 24 months of age while, for females, post-weaning benefits continued throughout life. Orphaning resulted in compromised male physical condition as measured by a reduced probability of growing antlers by 16 months of age while no evidence for compromised reproduction was found in females. These results support assertions that post-weaning maternal associations affect the development and survival of offspring.

1. Female ungulates are often selectively harvested according to their reproductive status. Because ungulate population growth depends heavily on adult female survival, it is crucial to understand the effects of this selective harvest. Recent studies revealed persistent individual differences in female reproductive potential, with a positive correlation of reproductive success over consecutive years. If current reproduction is correlated with lifetime reproductive success, then selective harvest of non-lactating females should remove individuals of low reproductive potential, with lower impact on population growth than random harvest. If lifetime reproductive success has a genetic basis, selective harvest may also increase the proportion of successful females. 2. We used an individual-based model to understand the short-term effects of harvest intensity and hunter selectivity on population dynamics, accounting for both heterogeneity in reproductive potential and orphan survival. We also explored the long-term effect of harvest as a selective pressure on female heterogeneity. 3. Selective harvest of non-lactating females reduced survival to primiparity compared to random harvest, because of high harvest rates of pre-reproductive females. After primiparity, however, females of higher reproductive potential had higher survival under selective than random harvest. Therefore, the overall effect on population dynamics depends on a trade-off between a high harvest of pre-reproductive females and a reduced harvest of reproductive females with high reproductive potential. 4. Female heterogeneity and the length of the pre-reproductive period affected this trade-off. Over the short term, high heterogeneity in reproductive potential of pre-reproductive females made selective harvest the most effective strategy to maintain a high population growth rate. With low heterogeneity and little effects of orphaning on juvenile mortality, however, random harvest had a lower impact on population growth than selective harvest. Over the long term, selective female harvest may increase the proportion of successful reproducers in the population. 5. Synthesis and applications. Selective harvests of non-lactating females appear justified only if female heterogeneity in reproductive potential and/or orphan mortality are very high. Because pre-reproductive females will be subject to intense harvest, selective harvest may reduce population growth rate compared to random harvest in species with late primiparity, especially if most pre-reproductive female normally survive to primiparity. When heterogeneity in reproductive potential and orphan mortality are low, random female harvest appears preferable to selective harvest.

In large mammals, regulations or hunter preference often lead to selective harvest of non‐lactating females, with unknown impacts upon population growth. Because female survival has very high elasticity effects on population growth, an assessment of the magnitude and selectivity of female harvest is crucial to understand population dynamics of sport‐hunted ungulates. Hunting accounts for most mortality of adult chamois Rupicapra rupicapra and regulations typically discourage the harvest of lactating females as orphaned kids have reduced survival rates. We used an individual‐based model, produced from empirical data, to explore the effects of selective removal of non‐lactating females on chamois population dynamics. Harvest intensity had much stronger effects on female population dynamics than selectivity for reproductive status. Selective harvest of non‐lactating females had very weak effects on population size and then only at a high harvest rate and under strong selectivity. Assuming no difference in winter survival between orphaned and non‐orphaned kids, harvest of non‐lactating females decreased population size at equilibrium compared to a random female harvest, whereas the opposite was true when assuming 50% lower survival of orphaned kids. Selective harvest of non‐lactating females may avoid the negative effects of orphaning on juvenile survival, but increases mortality of pre‐reproductive females that normally enjoy high survival and have high reproductive value. Synthesis and applications. The impact of selective harvest of non‐lactating females upon population dynamics is likely to be more affected by the age structure of lactating and non‐lactating females rather than by the survival of orphan and non‐orphan juveniles. High harvest of pre‐reproductive females has undesirable effects on population dynamics, which must be considered alongside any cultural preferences of hunters when developing hunting regulations or policies.

In this study, new data is collected from Tanzania to examine the impact of orphanhood on children's school attainment and height. The unique features of the data set will allow estimation of the long-term, persistent impact of orphanhood shocks during childhood on adult health and educational attainment, based on a sample of children that were initially non-orphaned, controlling for a wide variety of characteristics before the loss of a parent and allowing for migration since the baseline.

A common by-product of human harvesting is orphaning of calves in autumn. Despite this, there are few studies in northern and temperate ungulates evaluating the fate of orphaned calves and the potential benefits to offspring and costs to mothers of post-weaning maternal care. We manipulated orphaning and forage distribution during winter for two herds of reindeer ( Rangifer tarandus ): one nonfed and the other supplementally fed to increase level of interference competition. Both herds consisted of females with and without calves at heel and orphaned calves. We measured survival and somatic losses during winter and distances between mother–calves and adult females–orphans within the herds. All females survived the winter, and there was no evidence of post-weaning maternal cost in terms of female’s mass loss. The winter mortality among calves was negligible and did not differ between orphans as compared to nonorphans. However, nonorphaned calves lost less mass and stayed closer to their mothers than orphans to adult females, suggesting that increased mortality might occur in harsher winters. This tended to be more marked in the fed group where interference competition was more likely due to feed being concentrated both in space and time. Reduced mass loss in nonorphans is therefore most likely due to mothers sharing and defending feeding resources and protecting their offspring from harassment by other herd members during their first winter. We conclude that hunting practise of northern and temperate ungulates where females having calf/calves at heel are intentionally or non-intentionally harvested, may have demographic side effects at least in harsh winters.

The issue of orphan care has risen to the top of the social protection agenda in Malawi, where the prevalence of orphaned children has dramatically increased because of early deaths of parents infected by the HIV/AIDS virus. According to the Malawi Poverty Reduction Strategy Paper, prepared by the Government of Malawi in 2002, HIV infection rates in the 15-49 age group was at around 15% nationally. The paper reported that about 70,000 children become orphans every year, adding to the already large number of orphans, estimated at about 850,000.

The termite Coptotermes gestroi (Wasmann 1896) (Rhinotermitidae: Coptotermitinae) is an exotic species in Brazil and information concerning its reproductive developmental biology is scarce. We induced the formation of neotenics in laboratory colonies through orphaning experiments. Orphaning experiments were conducted in three-year old colonies of C. gestroi kept under laboratory conditions. After three months, eight nymphoid neotenics were observed in one colony after queen removal. Histological analysis showed that these neotenics were non-functional. The results suggest that these individuals may have arisen from the first nymphal instar (N1) or from an early N1 instar after one or two larval moults. Neotenics also were recorded on two incipient colonies of C. gestroi that lost the queen naturally.

This study is motivated by the high HIV prevalence in Mozambique, which, among adults aged 15-45 years in 2005, is estimated to be about 16.2% and is projected to climb (INE et al. 2004). By 2003 an estimated 400,000 Mozambicans had died of AIDS-related causes since 1991, and this number is projected to grow rapidly through the rest of the decade to double by 2010. Due to the tendency of the pandemic to strike young adults, AIDS-related deaths leave significant numbers of orphans in their wake.