Patterns Of Parental Investment Research Articles

The Difference of Parental Investment Model Between Multi-child Family and One-child Family

This study compared the parental investment patterns of multi-child families and single-child families. Through comparative analysis of the two family types, it is found that they have some differences in parental investment behavior. The results show that families with many children pay more attention to the cultivation of parent-child relationship, while families with only one child pay more attention to the cultivation of individual ability and independence. The research also found that the two kinds of families have differences in education investment, time investment and emotional investment, and different family types have their own characteristics and advantages in parental investment. These findings have important implications for understanding the differences in parental investment between different family types.

Bigger Is Better, Sometimes: The Interaction between Body Size and Carcass Size Determines Fitness, Reproductive Strategies, and Senescence in Two Species of Burying Beetles

The cost of reproduction hypothesis suggests that allocation to current reproduction constrains future reproduction. How organisms accrue reproductive costs and allocate energy across their lifetime may differ among species adapted to different resource types. We test this by comparing lifetime reproductive output, patterns of reproductive allocation, and senescence between two species of burying beetles, Nicrophorus marginatus and N. guttula, that differ in body size, across a range of carcass sizes. These two species of burying beetles maximized lifetime reproductive output on somewhat different–sized resources. The larger N. marginatus did better on large and medium carcasses while the smaller N. guttula did best on small and medium carcasses. For both species, reproduction is costly and reproduction on larger carcasses reduced lifespan more than reproduction on smaller carcasses. Carcass size also affected lifetime reproductive strategies. Each species’ parental investment patterns were consistent with terminal investment on carcasses on which they performed best (optimal carcass sizes). However, they exhibited reproductive restraint on carcass sizes on which they did not perform as well. Reproductive senescence occurred largely in response to carcass size. For both species, reproduction on larger carcasses resulted in more rapid senescence. These data suggest that whether organisms exhibit terminal investment or reproductive restraint may depend on type and amount of resources for reproduction.

Coevolution influences the evolution of filial cannibalism, offspring abandonment and parental care.

Understanding evolutionary patterns of parental investment and care has been a long-standing focus in studies of evolutionary and behavioural ecology. Indeed, patterns of investment and care are highly diverse, and fully understanding such diversity has been challenging. Recently, several studies have highlighted the need to consider coevolutionary dynamics in studies of parental care, as parental care is likely to co-occur and co-originate with a range of other traits. Two traits that commonly co-occur with parental care are offspring abandonment (the termination of parental investment prior to full independence in offspring) and filial cannibalism (the consumption of one's offspring). Here, we use a mathematical framework to explore how co-occurrence and coevolution among care, abandonment and cannibalism can influence the life-history conditions under which care is expected to evolve. Our results suggest that in some cases, the evolution of parental care can be inhibited by offspring abandonment and filial cannibalism. In other cases, abandonment and filial cannibalism that benefits parents can promote the evolution of parental care. It is particularly interesting that behaviours that seem so contrary to care-that is, eating or abandoning one's young-can in some cases broaden the conditions under which care can evolve. In general, our findings highlight that considering co-occurrence and coevolutionary dynamics between two or more traits is essential to understanding the evolution of trait diversity.

Parental investment asymmetries of a globally endangered scavenger: unravelling the role of gender, weather conditions and stage of the nesting cycle

ABSTRACTCapsule: In Egyptian Vultures Neophron percnopterus, both sexes invested similar parental effort throughout the breeding period. However, there was variation in the degree of intensity of parental care during some stages of the breeding period, suggesting that sex-role specialization exists for some activities.Aims: To quantify parental care behaviour of Egyptian Vultures for the first time and to examine the role of sex, weather conditions, and stage of nesting cycle on breeding ecology.Methods: We monitored 15 nests of Egyptian Vultures to analyse parental care investment. We collected data on nine different behavioural parameters/activities per sex, which were recorded throughout the entire breeding period. Variation in parental investment was analysed using generalized linear mixed models.Results: Females invested more effort in incubation/brooding (61.45% for females and 31.54% for males) and egg turning (0.45 events/h for females and 0.37 events/h for males) while males contributed more to nest material delivery to the nest (0.67 deliveries/h for males and 0.14 deliveries/h for females). Conversely, both sexes invested the same effort in nestling attendance (21.89% for females and 21.21% for males) and food provisioning (0.28 items/h for females and 0.25 items/h for males). Furthermore, parental investment was not affected by weather, especially during critical moments such as incubation/brooding, however, changeover rate was positively related to temperature.Conclusion: Our results suggest that, in the Egyptian Vulture, one sex is not entirely responsible for a particular task and the compensatory effort of the other mate is required. Finally, our findings indicate that major events such as incubation onset and hatching caused important shifts in the patterns of parental investment.

Deadbeats or losers: Discretionary male parental investment can make females less choosy

Two of the most important reproductive decisions that animals face are how to choose mates and how to invest in offspring. In species where both males and females provide offspring care, these selection pressures will often be reciprocally intertwined: mate preferences may depend on parental investment patterns while parental investment patterns may depend on mate preferences. We describe and analyze a mathematical model of this interaction, in which females can choose amongst males who have high attractiveness or low attractiveness, while males can decide whether to provide offspring care. We compare the case where males decide whether to provide care to the cases where males always provide care and where they never provide care. For a wide range of parameter settings, we find that when males decide whether to provide care, females are selected to be less choosy. This reduction in female choosiness occurs even though discretionary male care leads to greater variation among males in their offspring output. This finding contrasts with previous theoretical studies, and is driven by our assumption that males can decide whether to help provide care after mating occurs. Our results show how the interdependencies between mate choice and parental care can generate outcomes that can only be understood by considering both processes simultaneously.

Differential effects of food availability and nest predation risk on avian reproductive strategies

Spatial and temporal variation in resource abundance and predation risk can favor the evolution of phenotypic plasticity as a means of tracking changing environments. However, because food abundance and predation risk often covary in nature, few studies have separated their effects or tested whether different phenotypic traits respond to the same sources of environmental variation. We investigated patterns of parental investment and behavior over a 7-year period in 2 island populations of orange-crowned warblers (Oreothlypis celata) that showed little genetic divergence but experienced dramatic temporal variation in rainfall and spatial variation in nest predation risk. The amount of rainfall in each year was correlated with food abundance, and birds on both islands initiated breeding earlier and laid larger clutches in wetter years. In contrast, the rate at which parents visited their nests was not affected by rainfall but was negatively correlated with nest predation risk both within and between islands. Our results suggest that although the effects of food availability and nest predation have been viewed as mutually exclusive drivers of entire suites of life-history and behavioral traits, these traits can differ in their sensitivity to resource abundance or mortality risk, and traits that are often correlated can be decoupled under appropriate environmental conditions.

Inbreeding and the evolution of sociality in arthropods

Animals have evolved strategies to optimally balance costs and benefits of inbreeding. In social species, these adaptations can have a considerable impact on the structure, the organization, and the functioning of groups. Here, we consider how selection for inbreeding avoidance fashions the social behavior of arthropods, a phylum exhibiting an unparalleled richness of social lifestyles. We first examine life histories and parental investment patterns determining whether individuals should actively avoid or prefer inbreeding. Next, we illustrate the diversity of inbreeding avoidance mechanisms in arthropods, from the dispersal of individuals to the rejection of kin during mate choice and the production of unisexual broods by females. Then, we address the particular case of haplodiploid insects. Finally, we discuss how inbreeding may drive and shape the evolution of arthropods societies along two theoretical pathways.

Sex-specific effects of size and condition on timing of natal dispersal in kangaroo rats

The effects of proximal cues in eliciting natal dispersal are predicted to vary between sexes because of differences in reproductive strategies. I examined how body mass and condition affected timing of natal dispersal in male and female banner-tailed kangaroo rats (Dipodomys spectabilis), a species that lacks sex-biased dispersal. I experimentally manipulated cues by providing additional food to a subset of offspring prior to dispersal. All supplemented offspring, regardless of sex, grew faster, were in better condition, and had higher survivorship than unsupplemented offspring. Sons who received food supplements dispersed earlier than unsupplemented sons, indicating that timing of dispersal was related to size and condition. Timing of dispersal in daughters was unaffected by resource supplementation, suggesting that size and condition are less important proximal cues. These sex-specific responses match the intersexual differences in mammalian reproductive strategies and parental investment patterns. My results support the hypothesis that sons remain at the natal territory until a certain threshold of size and condition is reached. Male reproductive success is typically dependent on body size, which affects their ability to find and defend mates. By allowing sons to remain at the natal territory until this threshold is attained, mothers likely increase the fitness of their sons. Female reproductive success is influenced more by securing resources than by body size. Thus, dispersing as early as developmentally feasible would allow daughters to secure an existing burrow system and maximize the time available for caching food prior to their first breeding attempt. Copyright 2011, Oxford University Press.

The ecological basis of unusual sex roles in reverse-dichromatic eclectus parrots

In theory, sex roles are determined by the potential reproductive rates of males and females, which are constrained by parental investment. Thus the sex that invests least in offspring typically competes most for matings and is most subject to sexual selection, whereas the caring sex is most choosy when selecting mates. Here I show that ecological variables, rather than patterns of parental investment, can be influential in determining sex roles and the direction of sexual selection. In the polyandrous eclectus parrot, Eclectus roratus , both sexes care for offspring, yet despite traditional parental care patterns, both sexes are competitive and both are subject to sexual selection. The bright red and blue females compete for scarce nest hollows and the iridescent green males for mates. Using data from an 8-year field study, I show that the major ecological variable driving this system is nest hollow quality. Females with drier hollows had higher reproductive success and more males feeding and competing to mate with them. Females with nest hollows that were prone to flooding had fewer fledglings in years with higher dry season rainfall, confirming that hollow quality was a primary determinant of reproductive success. Comparisons of females before and after they changed hollows during the study provided further evidence that these trends were due to hollow quality rather than individual female quality. Thus competition for a scarce resource can lead to high variance in female reproductive success, and promote competition for high-quality mates among males.

Social biology of the wood-feeding cockroach genus Salganea (Dictyoptera, Blaberidae, Panesthiinae): did ovoviviparity prevent the evolution of eusociality in the lineage?

Recent phylogenetic studies indicating that termites are eusocial cockroaches closely related to the genus Cryptocercus have generated fresh interest in wood-feeding Blattaria. Here we summarize the social biology of the wood-feeding genus Salganea (Blaberidae: Panesthiinae). As in Cryptocercus, Salganea exhibits long term, biparental care that includes the defense and feeding of young nymphs. Unlike Cryptocercus, however, Salganea is iteroparous: most studied species reproduce periodically over their lifetime. These divergent reproductive strategies are likely related to parental costs associated with their differing reproductive modes: Cryptocercus is oviparous, while Salganea is ovoviviparous. The pattern of parental investment associated with ovoviviparous reproduction may be one reason why Salganea and other ovoviviparous wood-feeding cockroach lineages did not evolve eusociality.

Differences in parental food allocation rules: evidence for sexual conflict in the blue tit?

Evolutionary conflicts of interest between family members are expected to influence patterns of parental investment. In altricial birds, despite providing the same kind of parental care, patterns of investment in different offspring can differ between parents, a situation termed parentally biased favoritism. Previous explanations for parentally biased favoritism have received mixed theoretical and empirical support. Here, we test the prediction that in blue tits, Cyanistes caeruleus, females bias their food allocation rules to favor the smallest offspring during the nestling stage. By doing so, females could increase the subsequent amount of paternal care supplied by their partner during the fledging period, as a previous study showed that males feed the largest fledglings. When size differences within the brood are less pronounced, all offspring will require similar amounts of postfledging care, and thus, the male parent will lose the advantage of caring for the largest offspring that are closest to independence. In this study, we controlled the hunger of the smallest and largest nestlings in the brood and compared the food allocation rules of the 2 parents. We found that the male parent had a stronger preference than the female to feed the closest nestlings and made no distinction between nestlings based on size, whereas the female provisioned small hungry nestlings more when they were at intermediate distances from her. These differences in parental food allocation rules are consistent with predictions based on sexual conflict over postfledging parental investment.

Investimento parental e desenvolvimento da criança

Segundo a teoria do investimento parental, seria esperada uma relação entre condições de criação da mãe e sua carreira reprodutiva e, por conseqüência, seus padrões de cuidado aos filhos, com repercussões no desenvolvimento das crianças. Esta pesquisa buscou verificar essas relações, em amostra de 37 mães e seus filhos entre um e quatro anos, de um bairro pobre de Salvador, Bahia. Foi investigada a história familiar e reprodutiva das mães, associada a resultados desenvolvimentais das crianças, medidos através das escalas Bayley e WIPPSI-R, em quatro avaliações realizadas ao longo de três anos. Foram encontradas correlações entre condições de criação da mãe e sua carreira reprodutiva subseqüente. Por sua vez, esses padrões mostraram-se modestamente relacionados ao desenvolvimento cognitivo de seus filhos, favorecendo as crianças cujas mães iniciaram sua vida reprodutiva mais tarde. Os resultados são, em geral, compatíveis com a teoria do investimento parental. Limitações do estudo e perspectivas futuras são discutidas.

The marriage squeeze in Colombia, 1973–2005: The role of excess male death

Abstract Colombia has been characterized by extreme levels of civil violence throughout the latter part of the twentieth century, and the burden of excess mortality attributable to this violence has been borne primarily by young men. Populations with a large violent death burden are likely to experience consequences in terms of (1) marriage markets, (2) the dynamics of family formation and dissolution, and (3) patterns of parental investment in offspring. Using data from national censuses and household surveys, we calculate a measure of the marital sex ratio in order to explore the impact of differential male mortality on marriage markets in Colombia. Overall, Colombia is characterized by a female biased sex ratio at all ages. This relative excess of women is particularly pronounced in certain departments of the Central and Pacific regions which have been especially affected by civil violence. We suggest that the low sex ratios which characterized Colombia are partially responsible for the increasingly hi...

WHEN NOT TO AVOID INBREEDING

Avoidance of incestuous matings is widely reported across many animal taxa, and the adaptive value of such behavior is explained through inbreeding depression. However, an old and somewhat neglected theoretical result predicts that inbred matings offer another, positive effect on the inclusive fitness of parents: an individual who mates with a relative will help that relative to spread genes identical by descent. This benefit can be substantial, if the additional mating achieved by the relative does not harm his mating success otherwise, and in the context of selfing in plants the phenomenon is well known. Here, we develop a model that derives expected values of inbreeding tolerance, that is, the magnitude of inbreeding depression that is required to make individuals avoid inbreeding, for different animal life histories and parental investment patterns. We also distinguish between simultaneous and sequential mate choice, and show that inbreeding tolerance should often be remarkably high in the latter scenario in particular, although egalitarian parental care will lead to lower tolerance. There is a mismatch between theory and data: the almost complete lack of cases where individuals prefer to mate incestuously is at odds with a large overlap between the predicted range of inbreeding tolerance and estimates of inbreeding depression found in nature. We discuss four different solutions to this enigma, and suggest that inbreeding tolerance, where it is found, should not always be attributed to a simple constraint that has prevented finding any other mate.

WHEN NOT TO AVOID INBREEDING

Avoidance of incestuous matings is widely reported across many animal taxa, and the adaptive value of such behavior is explained through inbreeding depression. However, an old and somewhat neglected theoretical result predicts that inbred matings offer another, positive effect on the inclusive fitness of parents: an individual who mates with a relative will help that relative to spread genes identical by descent. This benefit can be substantial, if the additional mating achieved by the relative does not harm his mating success otherwise, and in the context of selfing in plants the phenomenon is well known. Here, we develop a model that derives expected values of inbreeding tolerance, that is, the magnitude of inbreeding depression that is required to make individuals avoid inbreeding, for different animal life histories and parental investment patterns. We also distinguish between simultaneous and sequential mate choice, and show that inbreeding tolerance should often be remarkably high in the latter scenario in particular, although egalitarian parental care will lead to lower tolerance. There is a mismatch between theory and data: the almost complete lack of cases where individuals prefer to mate incestuously is at odds with a large overlap between the predicted range of inbreeding tolerance and estimates of inbreeding depression found in nature. We discuss four different solutions to this enigma, and suggest that inbreeding tolerance, where it is found, should not always be attributed to a simple constraint that has prevented finding any other mate.

Patterns of Parental Investment and Sexual Selection in Teleost Fishes: Do They Support Bateman's Principles?

Bateman demonstrated differences in variance for fertility and mating success between the sexes, with males usually having a greater variance than females. Thus in general, male reproductive success increases with number of mates acquired. These results have been referred to as "Bateman's principles" and taken together with other parameters (e.g., relative parental investment) have been proposed to estimate a component of sexual selection. For this review I examine patterns of parental care and sexual selection in teleost fishes (substrate brooding and with internal fertilization). I present data for the pumpkinseed sunfish Lepomis gibbosus, in which I estimated cost of paternal care and compared direct measures of the intensity of selection on possible sexually selected traits to measures of sexual selection based on Bateman's principles.Despite high levels of paternal care in substrate brooding fishes, sexual selection tends to act more strongly on males than on females, which suggests that maternal investment is higher than paternal investment and that parental care does not limit the reproductive rate for males. In pumpkinseed sunfish, selection favors parents with high levels of defense that may exclude predators more effectively and, as suggested by Bateman's measures, alternative reproductive strategies may decrease the opportunity for sexual selection within the parental strategy. In teleost fishes with internal fertilization, patterns of parental investment and intensity of sexual selection seem to support Bateman's principles, but further studies using these systems and these measures of selection will improve the understanding of factors affecting the intensity of sexual selection and its relation to mating systems.

Don't Throw Bateman Out with the Bathwater!

Bateman identified two aspects of sexual selection. The first, called Bateman's principle, is that sexual selection favors increased promiscuity of males but not of females as a result of differences in parental investment in gametes. The second is that the variance in mate number of males is the fundamental cause of a sex difference in fitness variance. We argue that Bateman's insight about the source of sexual selection is more fundamental than his speculation about patterns of parental investment. We show that, when the sex ratio is 1:1, the average female must be as promiscuous as the average male, because each copulation involves one male and one female. Because mean male and female promiscuity are tied together in the same manner as mean male and female fitness, a sex difference in mating propensity must be the result of either (1) a sex difference in the covariance between matings and number offspring, or (2) Fisherian run-away sexual selection, wherein female reluctance to mate is a weak form of female choice. We show how female promiscuity can limit the evolution of male promiscuity, turning the central argument of parental investment theory on its head.

Chat-up lines as male sexual displays

Chat-up lines, and other openings used to initiate a relationship with a woman, can be viewed as male displays. How well does their effectiveness accord with predictions from evolutionary psychology? 205 undergraduates (142 female, 63 male) rated 40 vignettes; in each vignette, a man approached a woman and the raters judged whether she would continue the conversation. Openings involving jokes, empty compliments and sexual references received poor ratings. Those revealing, e.g., helpfulness, generosity, athleticism, ‘culture’ and wealth, were highly rated. Although the length of the vignette—confounded here with item content—affected the rating, differences remained after the effects of length were eliminated. The success of openings which demonstrated culture was predicted from Miller’s (2000) ‘mating mind’ hypothesis; the success of others could be predicted from patterns of parental investment.

Parental investment and family dynamics: interactions between theory and empirical tests

AbstractThe pattern of parental investment (PI) seen in nature is a product of the simultaneous resolution of conflicts of interest between the members of a family. How these conflicts are resolved depends upon the mating system, the genetic mechanism, on whether extra PI affects current or future offspring, and the behavioural mechanisms underlying supply and demand of PI. Until recently very little empirical work has been done to underpin these key determinants of conflict resolution. This review examines recent empirical progress in understanding both (1) how conflict is resolved and (2) its evolutionary consequences. How offspring demand interacts with parental supply of resources determines how conflict is resolved. Two extremes are: passive parental choice of competing offspring, relating to offspring control of resource allocation, and active parental choice relating to parental control. Although most previous empirical work has tended to conclude or assume that parents primarily control resource allocation decisions, recent studies explicitly examining predictions from theoretical analyses have shown that offspring control of resource allocation is more important than previously realised. The amount of PI supplied at resolution depends not on who controls food allocation, however, but on the nature of the supply and demand mechanisms. These have yet to be established experimentally, but a recent regression model illustrates how this could be achieved in the field. Determination of the effect of supply on demand (ESD) and the effect of demand on supply (EDS) mechanisms is critical to parent–offspring conflict theory, which has not been adequately tested empirically. There is an underlying, and until recently untested, assumption of models of intrafamilial conflict that there is genetic variation for both offspring demand and parental supply behaviours, so that the behaviours can coevolve. Recent studies on great tits, burrower bugs and mice all found evidence for genetic variation in supply and demand behaviours, but the predicted negative correlation between genes expressed in mothers and their offspring (i.e. parent–offspring coevolution), was found only for burrower bugs. The lack of a negative relationship for great tits and mice may have been a consequence of antagonistic coevolution between the sexes (sexual conflict). These studies illustrate the importance of the underlying genetics and mating system in determining conflict resolution, and point to the need for new models (especially of interbrood competition) taking differences in the genetics and the co‐evolution of the ESD and EDS mechanisms into account. We also discuss the importance of the comparative approach in determining evolutionary consequences of conflicts, and use the recent work on growth costs of begging to illustrate the difficulties of measuring costs of conflict in an evolutionary currency. The recent growth in empirical work on conflicts in families illustrates an increasing, and increasingly productive, integration between theoreticians and empiricists.

Environmental variability, life‐history covariation and cohort effects in the red‐billed choughPyrrhocorax pyrrhocorax

SummaryThe consequences of environmental variability for life‐history evolution are predicted to depend on the pattern of covariation amongst life‐history traits. Using data from a 20‐year study of individually marked red‐billed choughs, we investigate the short‐ and long‐term life‐history consequences of population‐wide variation in reproductive conditions, and demonstrate clear among‐cohort variation and covariation in life‐history parameters.The mean number of offspring fledging per breeding event varied among years, and was correlated with environmental conditions (temperature and rainfall) during the months preceding breeding. As the variance in breeding performance did not differ among years and choughs did not miss breeding seasons, variation in environmental conditions affected the whole breeding population. Thus the quality of the chough's breeding environment varied amongst years.Juvenile survival, the probability of recruitment to the breeding population and breeding longevity varied amongst cohorts, and these were positively correlated with the quality of the cohort's natal environment. Offspring fledging under good conditions were more likely to survive to breeding age and recruit, and had longer breeding lives than offspring fledging under poor conditions.Age at first breeding varied amongst cohorts, and increased with population size at maturity rather than natal conditions.The total number of offspring that recruits ultimately fledged varied primarily with breeding longevity rather than recruitment age. Thus, the consistent positive covariation amongst life‐history traits meant that the total number of offspring fledged by recruits during their breeding life varied amongst cohorts, and was correlated with the quality of a cohort's natal conditions. Choughs fledging under good conditions themselves ultimately fledged more offspring.Such environmentally determined variation in offspring fitness is expected to influence optimal patterns of parental investment. We discuss the predictions that environmental variability should select for investment in adult survival and for reduced reproductive effort in poor years.