Biology subjects

Bladon, E. K.

Publications and source records attributed to Bladon, E. K..

4 recordsLinked to original sources

bioRxiv2024

Plasticity and evolution of metabolic division of labour within families

Fluids produced by parents for dependent young, such as milk or regurgitate, carry molecules that assist offspring with growth, immunity and digestion, allowing the metabolic burden of development to be shared between parents and offspring. We tested whether this division of metabolic labour changes plastically and evolves when offspring are experimentally deprived of their parents metabolic assistance. In the burying beetle Nicrophorus vespilloides parents deposit oral fluids on their carrion nest during pre-hatching care, and facultatively transfer fluids to larvae through oral trophallaxis as post-hatching care. We analysed the oral fluid proteomes of replicate experimental populations that had been evolving for 50 generations with or without post-hatching care, and which were then allowed to raise larvae with or without post-hatching care for one experimental generation. We found that parents and larvae plastically and evolutionarily adjusted the proteins in their oral fluids when we prevented post-hatching care. When reared in the absence of post-hatching care, larvae that evolved without post-hatching care were also more capable of consuming carrion proteins than larvae that had evolved with post-hatching care, and had higher survival. Our results suggest that metabolic division of labour within families is plastically modulated, and that the extent of socially modulated plasticity can evolve rapidly when social conditions change.

evolutionary biology↗

bioRxiv2024

Nest construction and its effect on post-hatching family life in the burying beetle Nicrophorus vespilloides

Through the effort required to construct them, the microenvironmental conditions they impose on the family and their indirect influence on post-hatching care, nests play a key role in influencing family life. We combined experimental evolution with cross-fostering experiments on laboratory populations of Nicrophorus vespilloides to investigate three ways in which the nest can contribute more broadly to parental investment. We used replicate populations of N. vespilloides that had evolved for 42 generations under contrasting regimes of care. Populations were either able to supply post-hatching care ("Full Care") or prevented from supplying any post-hatching care ("No Care"). Research on these populations has previously shown that the No Care populations evolved to build rounder nests, more rapidly, by Generation 14. Here we found: 1) larvae raised by Full Care parents on nests prepared by parents from the No Care population did not attain a higher mass by the end of larval development than larvae in other treatments. However, we did discover that: 2) cross-fostering nests between families consistently reduced larval mass - and to a similar extent whether nests were cross-fostered between or within the populations. We suggest that cross-fostering disrupted the chemical environment on and around the nest since we found no evidence that 3) nests mediate interactions between males and females. The duration of paternal care was consistently shorter than the duration of maternal care, and even shorter for males from the No Care populations than males from the Full Care populations. Nevertheless, the duration of male care did not predict variation in duration of female care. In short, although the nest is the substrate for burying beetle family life, we found little evidence that it had evolved divergently in our experimental populations to influence parental investment.

evolutionary biology↗

bioRxiv2022

The role of recent evolutionary history in resilience to environmental change: social evolution effects versus founder effects

Principles of social evolution have long been used retrospectively to interpret social interactions, but have less commonly been applied predictively to inform conservation and animal husbandry strategies. We investigate whether differences in developmental environment, facilitated by divergent social conditions, can predict resilience to environmental change. Upon exposure to harsh novel environments, populations that previously experienced more benign social environments are predicted either to suffer fitness losses (the "mutation load hypothesis" and "selection filter hypothesis") or maintain fitness (the "beneficial mutation hypothesis"). We tested these contrasting predictions using populations of burying beetles Nicrophorus vespilloides we had evolved experimentally for 45 generations under contrasting social environments by manipulating the supply of post-hatching parental care. We exposed sexually immature adults from each population to varying heat stress and measured the effect on survival and reproduction. The greater the level of parental care previously experienced by a population, the better its survival under heat stress during sexual maturation. Although this is consistent with the "beneficial mutation hypothesis", it is also possible that populations that had evolved without post-hatching care were simply more prone to dying during maturation, regardless of their thermal environment. Overall, we suggest that stochastic genetic variation, probably due to founder effects, had a stronger influence on resilience. We discuss the implications for translocation and captive breeding programmes. Lay summaryCan we use knowledge of a populations evolutionary history to predict how individuals might cope with environmental change? We investigated whether burying beetles that had evolved for 45 generations with or without post-hatching parental care differed in their resilience to extreme temperatures as they developed to sexual maturity. We found limited evidence that experimental evolution under different regimes of parental care contributed to thermal resilience, which instead was better explained by chance historical events.

evolutionary biology↗

bioRxiv2022

The evolutionary demise of a social interaction: social partners differ in the rate at which interacting phenotypes are lost

Phenotypic plasticity enables animals to adjust their behaviour flexibly to their social environment - sometimes through the expression of adaptive traits that have not been exhibited for several generations. We investigated how long social adaptations can usefully persist when they are not routinely expressed, by using experimental evolution to document the loss of social traits associated with the supply and demand of parental care. We allowed populations of burying beetles Nicrophorus vespilloides to evolve in two social environments for 48 generations in the lab. In Full Care populations, traits associated with the supply and demand of parental care were expressed at every generation, whereas in No Care populations we prevented expression of these traits experimentally. We then revived trait expression in the No Care populations at generations 24, 43 and 48 by allowing parents to supply post-hatching care, and compared these social traits with those expressed by the Full Care populations. We found that offspring demands for care decayed in the No Care populations more rapidly than a parents capacity to supply care. Furthermore, male care decayed before female care. We suggest that this reflects differences in the strength of selection for the expression of alternative traits in offspring, males and females, which can enhance fitness when post-hatching care is disrupted. Impact SummarySocial interactions between animals are suggested to be increasingly vulnerable to breakdown in our changing world. Our experiments offer a rare insight into what happens next, by assessing in real time the durability of social behaviours that are no longer routinely expressed. Our results also have implications for conservation captive breeding programmes where compensatory husbandry techniques prevent trait expression and so could inadvertently induce rapid, irreversible trait loss. We investigated how long it took populations to lose the ability to express appropriate social behaviour when they had been prevented from doing so for many generations. We did this by evolving replicate populations of burying beetles Nicrophorus vespilloides in the laboratory for 48 generations. The burying beetle is a common insect that is well-known for caring for its larvae, although larvae can survive in the lab without any care at all. In two populations ("Full Care"), we allowed parents and offspring to interact during the supply of post-hatching care, as usual. In two other populations ("No Care"), parents were removed before offspring hatched and so could not interact socially with their young. Over the course of 48 generations of experimental evolution, we periodically revived social interactions between parents and offspring in the No Care populations. We assessed the extent to which larval begging behaviours, and parental care behaviours, had decayed by comparing their expression with those in the Full Care populations. We found that larval begging behaviour eroded rapidly in No Care populations, and more rapidly than the supply of care by parents. Furthermore, paternal care decayed to a greater extent than maternal care (which was largely unchanged relative to its expression in the Full Care populations). We suggest that these differences could be due to differences in the strength of selection on each family member for alternative traits to enhance fitness.

evolutionary biology↗