Per T Smiseth

• PhD
• Lecturer at University of Edinburgh

The evolution of sibling competition is promoted when the brood's demand for resources (brood size) exceeds the parents' supply of resources (resource availability). However, little is known about the joint effects of brood size and resource availability and whether these effects are independent of each other. We conducted a study on the burying be...

Conflict over resources is a fundamental component of family life. Family conflicts are predicted to be strongly influenced by resource availability and levels of relatedness between family members. Here, we examined the effects of these factors on intra-brood sibling conflict in a family living beetle, Nicrophorus vespilloides, where offspring are...

The hurry-up hypothesis suggests that completing reproduction as soon as possible is favored when the quantity or quality of resources used for breeding declines over time. However, completing reproduction sooner may incur a cost if it leads to an asynchronous hatching pattern that reduces overall growth and survival of offspring. Here, we present...

In species with biparental care, males may be under selection to adjust the amount of care they provide for their offspring in response to losses in paternity. Previous work on birds and fishes provide mixed empirical evidence for facultative adjustments in male care to losses in paternity. One potential reason for this inconsistency is that males...

A recent theoretical model suggests that intraspecific competition is an important determinant of the severity of inbreeding depression. The reason for this is that intraspecific competition is density dependent, leading to a stronger negative effect on inbred individuals if they are weaker competitors than outbred ones. In support of this predicti...

The existence of life‐history trade‐offs is a fundamental assumption of evolutionary biology and behavioural ecology, yet empirical studies have found mixed evidence for this. Such trade‐offs are expected when individuals vary in how they allocate their limited resource budgets between different life‐history functions (variation in resource allocat...

Investigating fundamental processes in biology requires the ability to ground broad questions in species‐specific natural history. This is particularly true in the study of behavior because an organism's experience of the environment will influence the expression of behavior and the opportunity for selection. Here, we provide a review of the natura...

Inbreeding and inbreeding depression are important topics in evolutionary biology and conservation but relatively peripheral to the field of animal behavior. Here, we make a case for why the field of animal behavior should take a greater interest in inbreeding and inbreeding depression. Social interactions, including cooperation, competition, and c...

Biparental care occurs when males and females cooperate to care for their joint offspring. It is associated with sexual conflict because the benefits stem from the combined effort of both parents, while any costs depend on each parent's own effort. Thus, biparental care involves a delicate balance between cooperation and conflict. Shifts in this ba...

Studies investigating the trade-off between current and future reproduction often find that increased allocation to current reproduction is associated with a reduction in the number or quality of future offspring. In species that provide parental care, this effect on future offspring may be mediated through a reduced future ability to provide care....

A cost of reproduction may not be observable in the presence of environmental or individual heterogeneity because they affect the resources available to individuals. Individual space use is critical in determining both the resources available to individuals and the exposure to factors that mediate the value of these resources (e.g. competition and...

In species where both parents cooperate to care for their joint offspring, one sex often provides more care than the other. The magnitude of such sex differences often varies both between and within species and may depend on environmental conditions, such as access to resources, predation risk and interspecific competition. Here we investigated the...

Brood parasites lay their eggs in the nests of other females, thereby shifting the costs of offspring care onto others. Given that care is costly, potential hosts should evolve mechanisms to avoid brood parasitism. Meanwhile, brood parasites should evolve mechanisms to circumvent host defences. Here we investigate whether hosts or intraspecific bro...

Parental care is a key component of an organism’s reproductive strategy that is thought to trade-off with allocation toward immunity. Yet, it is unclear how caring parents respond to pathogens: do infected parents reduce care as a sickness behavior or simply from being ill or do they prioritize their offspring by maintaining high levels of care? To...

Differential allocation is the adjustment of reproductive allocation, typically by a female, in response to the quality of her male partner. A recent theoretical model suggests that differential allocation may influence trade-offs between reproductive traits within a breeding attempt. Furthermore, it is often difficult to distinguish differential a...

Offspring of many animals beg for food from parents. Begging is often costly, and offspring should seek to reduce such costs to maximize their returns on begging. Whenever multiple adults provide care for a joint brood, as in species where multiple females breed communally, offspring should beg toward the parent that provisions the most food. Here,...

Parental care is a key component of an organism’s reproductive strategy that is thought to trade-off with allocation towards immunity. Yet it is unclear how caring parents respond to pathogens: do infected parents reduce their amount of care as a sickness behaviour or simply from being ill, or do they prioritise their offspring by maintaining high...

Life-history trade-offs between the number and size of offspring produced, and the costs of reproduction on future reproduction and survival can all be affected by different levels of parental effort. Because of these trade-offs the parents and the offspring have different optima for the amount of care given to the current brood, which leads to a c...

Parents and offspring have different optima for the level of parental resource allocation and the timing of nutritional independence. Theoretical models assume that either parents or offspring control the allocation of resources within a brood; however, control may also be mutual. Here we investigate whether the resolution of parent‐offspring confl...

The existence of a trade‐off between current and future reproduction is a fundamental prediction of life history theory. Support for this prediction comes from brood size manipulations, showing that caring for enlarged broods often reduces the parent's future survival or fecundity. However, in many species, individuals must invest in competing for...

Inbreeding depression is defined as a fitness decline in progeny resulting from mating between related individuals, the severity of which may vary across environmental conditions. Such inbreeding‐by‐environment interactions might reflect that inbred individuals have a lower capacity for adjusting their phenotype to match different environmental con...

Cobreeding, which occurs when multiple females breed together, is likely to be associated with uncertainty over maternity of offspring in a joint brood, preventing females from directing resources towards their own offspring. Cobreeding females may respond to such uncertainty by shifting their investment towards the stages of offspring development...

In birds and other vertebrates, there is good evidence that females adjust the allocation of hormones in their eggs in response to prenatal environmental conditions, such as food availability or male phenotype, with profound consequences for life history traits of offspring. In insects, there is also evidence that females deposit juvenile hormones...

Much of our current understanding of coordination, cooperation, and conflict between male and female parents caring for their joint offspring derives from studies conducted on birds. However, biparental care is not unique to birds but has evolved repeatedly in a wide range of other taxa, including mammals, reptiles, amphibians, fishes, insects, and...

Wild quantitative genetic studies have focused on a subset of traits (largely morphological and life history), with others, such as behaviors, receiving much less attention. This is because it is challenging to obtain sufficient data, particularly for behaviors involving interactions between individuals. Here, we explore an indirect approach for pi...

Parental care is highly variable, reflecting that parents make flexible decisions about how much care to provide in response to variation in the cost and/or benefit of care. Handicapping has traditionally been used as a tool for increasing the energetic cost of care, thereby inducing a reduction in care by handicapped parents. However, recent evide...

Individuals vary with respect to their nutritional state and such variation is an important determinant of the amount of resources individuals allocate toward reproductive functions. Currently, we have a relatively poor understanding of the downstream consequences of food deprivation on different traits associated with reproduction. Here, we addres...

Understanding how animals respond to and cope with variation in ambient temperature is an important priority. The reason for this is that ambient temperature is a key component of the physical environment that influences offspring performance in a wide range of ectotherms and endotherms. Here, we investigate whether posthatching parental care provi...

Theory predicts that the outcome of mating interactions should be influenced by the condition of both males and females. First, females should base their mating decisions on reliable cues about male quality, which are often condition dependent. Second, the costs and/or benefits of being choosy during mating may depend on the female's own condition....

The severity of inbreeding depression often varies across environments and recent work suggests that social interactions can aggravate or reduce inbreeding depression. For example, stressful interactions such as competition can exacerbate inbreeding depression, whereas benign interactions such as parental care can buffer against inbreeding depressi...

Theory suggests that intraspecific competition associated with direct competition between inbred and outbred individuals should be an important determinant of the severity of inbreeding depression. The reason is that, if outbred individuals are stronger competitors than inbred ones, direct competition should have a disproportionate effect on the fi...

Individual variation in resource acquisition should have consequences for life‐history traits and trade‐offs between them because such variation determines how many resources can be allocated to different life‐history functions, such as growth, survival and reproduction. Since resource acquisition can vary across an individual's life cycle, the con...

Interactions among siblings fall on a continuum with competition and cooperation at opposite ends of the spectrum. Prior work on the burying beetle Nicrophorus vespilloides suggests that parental care shifts the balance between competition and cooperation by masking a density‐dependent shift from cooperation to competition. However, these results s...

Despite an extensive body of theoretical and empirical literature on biparental cooperation, it is still unclear whether offspring fare equally, better or worse when receiving care by two parents versus a single parent. Some models predict that parents should withhold the amount of care they provide due to sexual conflict, thereby shifting as much...

In species where family members share a limited pool of resources, there may be competition between parents and their dependent offspring for access to these resources. Parent–offspring competition may impose a cost to family living that would constrain the evolution of parental care and family living. Yet, few studies have tested for evidence of p...

In species with biparental care, begging offspring may preferentially associate with or beg more towards one of their parents. Such preferences may reflect that the benefits of begging vary with the parent's sex given that females and males often differ in the amount of care they provide and/or in their responsiveness to begging levels. Alternative...

There is growing interest in how environmental conditions, such as resource availability, can modify the severity of inbreeding depression. However, little is known about whether inbreeding depression is also associated with differences in individual decision-making. For example, decisions about how many offspring to produce are often based upon th...

We investigate the effect of offspring and maternal inbreeding on maternal and offspring traits associated with early offspring fitness in the burying beetle Nicrophorus vespilloides. We conducted two experiments. In the first experiment, we manipulated maternal inbreeding only (keeping offspring outbred) by generating mothers that were outbred, mo...

There is mounting evidence that inbreeding can have complex effects on social interactions among inbred and outbred individuals. Here, we investigate effects of offspring and maternal inbreeding on parent-offspring communication in the burying beetle Nicrophorus vespilloides. We find effects of the interaction between offspring and maternal inbreed...

The emergence of family groups is associated with conflict over the allocation of food or other limited resources. Understanding the mechanisms mediating the resolution of such conflict is a major aim in behavioral ecology. Most empirical work on familial conflict has focused on birds. Here, we highlight how recent work on insects provides new and...

Parental care is highly variable, reflecting that parents make flexible decisions in response to variation in the cost of care to themselves and the benefit to their offspring. Much of the evidence that parents respond to such variation derives from handicapping and brood size manipulations, the separate effects of which are well understood. Howeve...

In species with biparental care, females often provide more care than males. Previous work has focused on sex differences in parental food provisioning and defence against predators. However, parents often also defend their offspring against conspecific intruders, which could be male or female. Thus, there is a need for studies examining sex differ...

Egg size reflects the amount of energy that female parents have invested in their offspring prior to hatching, and is thus often used as a proxy for prehatching investment. According to life history theory, prehatching investment, in turn, trades off with posthatching investment, as the amount of resources allocated at the prehatching stage diminis...

Resource availability, through its impact on the costs and benefits of parental care, is expected to influence parental care behaviour. There has, to our knowledge, been no attempt to understand how variation in the resource use of wild individuals influences individual parental care behaviour. To understand how natural resource variability affects...

Significance In biparental species, sexual conflict arises as each parent attempts to minimize its personal effort. Most work has focused on how this conflict is resolved through symmetrical decisions between parents. We investigated whether females can influence male decisions by altering the offspring’s phenotype via the eggs. We manipulated the...

Keywords: burying beetle direct benefits inbreeding mate choice mating success Nicrophorus vespilloides sexual selection Inbreeding occurs when relatives mate with each other, and it often has detrimental effects for the fitness of any resulting offspring. It is an important issue in ecology and evolutionary biology with profound implications for g...

When estimating heritability in free-living populations, it is common practice to account for common environment effects, because of their potential to generate phenotypic covariance among relatives thereby biasing heritability estimates. In quantitative genetic studies of natural populations, however, philopatry, which results in relatives being c...

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreedi...

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreedi...

Winning or losing a prior contest can influence the outcome of future contests, but it might also alter subsequent reproductive decisions. For example, losers may increase their investment in the current breeding attempt if losing a contest indicates limited prospects for future breeding. Using the burying beetle Nicrophorus vespilloides, we tested...

The evolution of elaborate forms of parental care is an important topic in behavioral ecology, yet the factors shaping the evolution of complex suites of parental and offspring traits are poorly understood. Here, we use a multivariate quantitative genetic approach to study phenotypic and genetic correlations between parental and offspring traits in...

Winning or losing a prior contest can influence the outcome of subsequent contests, but it might also alter subsequent reproductive decisions. For example, losers may increase their investment in the current breeding attempt if losing a contest indicates limited prospects for future breeding. Using the burying beetle Nicrophorus vespilloides, we te...

about whether or not to help, which is likely to be influenced by lack of additional breeding opportunities. Alonzo (2016) finds our review a useful generalization of the manipulating androgens hypothesis (MAH) and argues that further work is needed to understand how sexual conflict shapes female life histories and how plasticity in maternal effect...

Sexual conflict arises whenever males and females have divergent reproductive interests. The mechanisms mediating the resolution of sexual conflict have been studied extensively in the context of parental care, where each parent adjusts its decision about how much care to provide based on its partner's workload. However, there is currently no infor...

Inbreeding results from matings between relatives and can cause a reduction in offspring fitness, known as inbreeding depression. Previous work has shown that a wide range of environmental stresses, such as extreme temperatures, starvation, and parasitism, can exacerbate inbreeding depression. It has recently been argued that stresses due to intras...

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreedi...

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreedi...

Inbreeding results from matings between relatives and can cause a reduction in offspring fitness, known as inbreeding depression. Previous work has shown that a wide range of environmental stresses, such as extreme temperatures, starvation, and parasitism, can exacerbate inbreeding depression. It has recently been argued that stresses due to intras...

Understanding how sexual conflict influences male and female parental decisions is a long-standing problem in behavioral ecology. Until now, most research on sexual conflict over parental care has focused on behavioral mechanisms mediating the resolution of this conflict through negotiation between parents. Here, we review evidence suggesting that...

In species with biparental care, sexual conflict occurs because the benefit of care depends on the total amount of care provided by the two parents while the cost of care depends on each parent's own contribution. Asynchronous hatching may play a role in mediating the resolution of this conflict over parental care. The sexual conflict hypothesis fo...

Handicapping experiments on species with biparental care show that a focal parent increases its contribution when its partner is handicapped. Such results are interpreted as evidence for negotiation, whereby each parent adjusts its amount of care to that of its partner. However, it is currently unclear whether the focal parent responds to a change...

Inbreeding avoidance reduces the probability that an individual will mate with a related partner, thereby lowering the risk that it produces inbred offspring suffering from inbreeding depression. Inbreeding avoidance can occur through several mechanisms, including active mate choice, polyan-dry and sex-biased dispersal. Here, we focus on the role o...

Handicapping experiments on species with biparental care show that a focal parent increases its contribution when its partner is handicapped. Such results are interpreted as evidence for negotiation, whereby each parent adjusts its amount of care to that of its partner. However, it is currently unclear whether the focal parent responds to a change...

Significance When relatives mate, their inbred offspring often suffer a reduction in fitness-related traits known as “inbreeding depression.” Environmental stresses such as starvation and competition can exacerbate these fitness costs of inbreeding. However, caring parents could mitigate the fitness costs of inbreeding by neutralizing the effects o...

Offspring begging can be triggered by a variety of acoustic, visual or chemical cues from the parents. In many birds, nestlings use information derived from these cues to discriminate between individual parents or different classes of adults. Although begging occurs in some insects, we know very little about discrimination between adults by insect...

Abstract There is mounting evidence that inbreeding can have detrimental effects on the fitness of outbred individuals that interact with or depend on inbred individuals. However, little is currently known about the behavioral mechanisms by which interactions with inbred individuals induce fitness costs in outbred individuals. Here, we study effect...

Intergenerational effects can have either adaptive or nonadaptive impacts on offspring performance. Such effects are likely to be of ecological and evolutionary importance in animals with extended parental care, such as birds, mammals and some insects. Here, we studied the effects of exposure to microbial competition during early development on sub...

Understanding the consequences of phenotypic variation in resource acquisition is an important problem in evolutionary ecology because such variation may impact on how parents balance resource investment in individual offspring against other life-history priorities. Here we investigate the effects of phenotypic variation in resource acquisition on...

1. Natural diversity in forms of parental care 2. Origin and evolution of parental care 3. Evolutionary maintenance of parental care 4. Genetics and epigenetics of parental care 5. Sociality beyond family

Offspring of many animals develop in environments in which they are exposed to high densities of potentially harmful bacteria. For example, larvae of the carrion beetle Nicrophorus vespilloides face significant challenges from the bacteria they encounter during their development on decomposing vertebrate carcasses. We tested the idea that larvae se...

Understanding the behavioral mechanisms mediating the resolution of parent–offspring conflict is an important challenge given that the resolution of this conflict shapes the transfer of resources from parents to offspring. Three alternative models suggest that offspring beg-ging provides an important behavioral mechanism for conflict resolution: ho...

Inbreeding depression is the reduction in fitness caused by mating between related individuals. Inbreeding is expected to cause a reduction in offspring fitness when the offspring themselves are inbred, but outbred individuals may also suffer a reduction in fitness when they depend on care from inbred parents. At present, little is known about the...

Parental care includes a wide variety of traits that enhance offspring development and survival. It is taxonomically widespread and is central to the maintenance of biodiversity through its close association with other phenomena such as sexual selection, life-history evolution, sex allocation, sociality, cooperation and conflict, growth and develop...

Parents can increase the fitness of their offspring by allocating nutrients to eggs and/or providing care for eggs and offspring. Although we have a good understanding of the adaptive significance of both egg size and parental care, remarkably little is known about the co-evolution of these two mechanisms for increasing offspring fitness. Here, we...

In species where parents provide their offspring with food, the offspring must undergo a transition from nutritional dependency to independence. Parent–offspring conflict theory predicts that the optimal timing for this transition will differ between parents and offspring and that the realised timing depends on each party’s ability to control the t...

Parents of many species care for their offspring by protecting them from a wide range of environmental hazards, including desiccation, food shortages, predators, competitors, and parasites and pathogens. Currently, little is known about the mechanisms and fitness consequences of parental defences against bacterial pathogens and competitors. Here, w...

Recently, there has been much interest in the role of endogenous and maternal hormones as regulators of offspring begging and mediators of parent-offspring conflict. Here, we review recent work in this field, and identify inconsistencies in the literature. We find good evidence that hormones play a role as regulators of begging: 13 studies report a...

In mammals, altricial birds and some invertebrates, parents care for their offspring by providing them with food and protection until independence. Although parental food provisioning is often essential for offspring survival and growth, very little is known about the conditions favouring the evolutionary innovation of this key component of care. H...

In birds, nestling begging is often triggered by visual or acoustic stimuli from parents. Although begging occurs in some insects, it is not known whether it is triggered by specific parental stimuli. The burying beetle Nicrophorus vespilloides has attracted interest as an insect system for studying parent--offspring communication. Recent work on t...

We studied the behaviour of grey seals, Halichoerus grypus, during the breeding period at Froan, Norway, and compared our findings with existing studies on grey seals at breeding sites in Britain and Canada. The pups at Froan spent more time in water than pups at other breeding sites. While on-shore, the pups at Froan spent most of their time resti...

The evolution of asynchronous hatching is a central yet controversial issue in evolutionary ecology and animal behaviour. Although asynchronous hatching has a widespread taxonomic distribution, past research has focused almost exclusively on altricial birds. We tested the peak load reduction hypothesis for the evolution of asynchronous hatching in...

The evolution of asynchronous hatching is a central yet controversial issue in evolutionary ecology and animal behaviour. Although asynchronous hatching has a widespread taxonomic distribution, past research has focused almost exclusively on altricial birds. We tested the peak load reduction hypothesis for the evolution of asynchronous hatching in...

Rich and ephemeral resources, such as carrion, are a source of intense interspecific competition among animal scavengers and microbial decomposers. Janzen [Janzen DH (1977) Am Nat 111:691–713] hypothesized that microbes should be selected to defend such resources by rendering them unpalatable or toxic to animals, and that animals should evolve coun...

Sex differences in parenting are common in species where both males and females provide care. Although there is a considerable body of game and optimality theory for why the sexes should differ in parental care, genetics can also play a role, and no study has examined how genetic influences might influence differences in parenting. We investigated...

Offspring of many animals signal their nutritional needs using conspicuous begging displays. Theoretical models for the evolution of begging suggest that costly begging signals provide an evolutionarily stable resolution to parent--offspring conflict because they provide parents with honest information on offspring need. However, other models sugge...

In altricial birds, the parents’ distribution of resources within the brood is influenced by variation in at least two components of nestling condition: hunger level and size rank. Here, we examine whether variation in larval hunger and size rank had similar influences on the parents’ distribution of resources in the burying beetle Nicrophorus vesp...

Animals of many species accept or solicit recurring copulations with the same partner; i.e., show repeated mating. An evolutionary explanation for this excess requires that the advantages of repeated mating outweigh the costs, and that behavioral components of repeated mating are genetically influenced. There can be benefits of repeated mating for...

Asynchronous hatching is an important component of animal reproductive strategies, yet it has been studied almost exclusively in altricial birds. In this study, we provide evidence on the adaptive consequences and the heritable basis of asynchronous hatching in an insect, the burying beetle Nicrophorus vespilloides. Parents of this species breed on...

The evolution of the complex and dynamic behavioural interactions between caring parents and their dependent offspring is a major area of research in behavioural ecology and quantitative genetics. While behavioural ecologists examine the evolution of interactions between parents and offspring in the light of parent-offspring conflict and its resolu...