Food availability and the male's role in parental care in double‐brooded Treecreepers Certhia familiaris

Evolutionary transitions among maternal, paternal, and bi-parental care have been common in many animal groups. We use a mathematical model to examine the effect of male and female life-history characteristics (stage-specific maturation and mortality) on evolutionary transitions among maternal, paternal, and bi-parental care. When males and females are relatively similar – that is, when females initially invest relatively little into eggs and both sexes have similar mortality and maturation – transitions among different patterns of care are unlikely to be strongly favored. As males and females become more different, transitions are more likely. If females initially invest heavily into eggs and this reduces their expected future reproductive success, transitions to increased maternal care (paternal → maternal, paternal → bi-parental, bi-parental → maternal) are favored. This effect of anisogamy (i.e., the fact that females initially invest more into each individual zygote than males) might help explain the predominance of maternal care in nature and differs from previous work that found no effect of anisogamy on the origin of different sex-specific patterns of care from an ancestral state of no care. When male mortality is high or male egg maturation rate is low, males have reduced future reproductive potential and transitions to increased paternal care (maternal → paternal, bi-parental → paternal, maternal → bi-parental) are favored. Offspring need (i.e., low offspring survival in the absence of care) also plays a role in transitions to paternal care. In general, basic life-history differences between the sexes can drive evolutionary transitions among different sex-specific patterns of care. The finding that simple life-history differences can alone lead to transitions among maternal and paternal care suggests that the effect of inter-sexual life-history differences should be considered as a baseline scenario when attempting to understand how other factors (mate availability, sex differences in the costs of competing for mates) influence the evolution of parental care.

The evolution of maternal, paternal, and bi-parental care has been the focus of a great deal of research. Males and females vary in basic life-history characteristics (e.g., stage-specific mortality, maturation) in ways that are unrelated to parental investment. Surprisingly, few studies have examined the effect of this variation in male and female life history on the evolution of care. Here, we use a theoretical approach to determine the sex-specific life-history characteristics that give rise to the origin of paternal, maternal, or bi-parental care from an ancestral state of no care. Females initially invest more into each egg than males. Despite this inherent difference between the sexes, paternal, maternal, and bi-parental care are equally likely when males and females are otherwise similar. Thus, sex differences in initial zygotic investment do not explain the origin of one pattern of care over another. However, sex differences in adult mortality, egg maturation rate, and juvenile survival affect the pattern of care that will be most likely to evolve. Maternal care is more likely if female adult mortality is high, whereas paternal care is more likely if male adult mortality is high. These findings suggest that basic life-history differences between the sexes can alone explain the origin of maternal, paternal, and bi-parental care. As a result, the influence of life-history characteristics should be considered as a baseline scenario in studies examining the origin of care.

In species with internal fertilization, but without parental care, an evolution of 'maternal care' is fundamentally different from an evolution of 'paternal care'. Maternal care should be a pure EES. Paternal care should always be superimposed on a mixed ESS to stay (or not to stay) and to establish some kind of a pair-bond with the female from copulation until egg-laying. This implies that paternal care is less reliable than maternal care. This could have led to the evolution of female strategies and properties which raise the chances for male care. The above considerations offer a framework for the evolutionary pathways between the various parental care strategies and between their associated mating systems. Both paternal and maternal care might directly evolve towards biparental care. For the evolution from paternal towards biparental care it is more likely, however, that a transitional stage of 'uniparental care' will be passed. That stage is characterized by paternal care in most cases, but by maternal care if the male deserts. It is probable that the biparental care system with similar roles for both sexes evolved along this route. Since such similar role systems are widely distributed among birds, and since monogamous paternal care systems can easily evolve towards all recent mating systems in birds, it is advocated that the evolution of parental care in birds was primarily based on a monogamous paternal care system.

Patterns of parental care and parental investment in marsupials.

Father-daughter and mother-son relationships: Parental bonding behaviours and socially prescribed perfectionism in young adults

Low parental care during childhood, a pattern characteristic of an "affectionless control" rearing style was frequently reported in the history of addicted individuals. Parents' childrearing regimes and children's genetic predispositions, with their own behavioral characteristics, have been seen to be closely interwoven, probably affecting children's development and addictive behavior susceptibility. In the present study, parents care perception, aggressive personality traits, and genotype (serotonin transporter promoter gene--5-HTTLPR) have been investigated in cocaine users and healthy control subjects. PBI scores (maternal and paternal care) were lower and BDHI scores (aggressiveness) higher in cocaine users in comparison with controls and significant differences in the perception of either paternal or maternal care were observed between cocaine users and non-users. The short-short (SS) genotype frequency was significantly higher among cocaine users compared with control subjects (P = 0.04). Logistic regression proves that persons bearing the SS genotype have a risk of becoming cocaine user almost three times higher than those having the LL genotype. Estimations of the effects of other factors potentially affecting the risk of being cocaine addicted clearly prove the significant impact of aggressiveness: the highest the score, the highest the risk of becoming cocaine user. Moreover, paternal and maternal care perception significantly improve the fit of the model (the log likelihood decreases passing from -105.9 to -89.8, LR test = 32.17, P-value = 0.0000). Each unit increase in the PBI score yields a significant 12% and 10% decrease of the risk of becoming cocaine user, respectively for paternal and maternal care. Interestingly, once controlled for the PBI score, the relative risk associated to the SS genotype drops strikingly and becomes no longer statistically significant. On the whole, our preliminary data suggest that the association between 5-HT transporter polymorphism and psycho-stimulant use may be mediated by mother-child relationship and parental attachment perception, both being environmental and genetic factors involved in the proneness to substance use disorders, particularly in aggressive-antisocial individuals.

Paternal care is rare in mammals, occurring mainly in carnivores and neotropical primates, in which the difficulties of long generation time and large individuals lead to small sample sizes. Here, the authors show that paternal care can be easily studied in the four-striped mouse (Rhabdomys pumilio) because (a) captive males show all the patterns of parental care as do females, with the obvious exception of nursing; (b) in the field, wild males act amicably toward juveniles and retrieve pups experimentally presented to them; (c) the striped mouse facilitates experimental approaches in captivity because it has a short generation period and can be kept in large numbers; and (d) the striped mouse is diurnal, not only making observations in captivity easier but also enabling direct observations in the field.

Causes of extra-pair paternity and its inter-specific variation in socially monogamous birds

Competing females and caring males. Sex steroids in African black coucals, Centropus grillii

Natural variations in maternal and paternal care are associated with systematic changes in oxytocin following parent–infant contact

The parental roles of males and females differ considerably between and within species. By means of individual-based evolutionary simulations, we strive to explain this diversity. We show that the conflict between the sexes creates a sex bias (towards maternal or paternal care), even if the two sexes are initially identical. When including sexual selection, there are two outcomes: either female mate choice and maternal care or no mate choice and paternal care. Interestingly, the care pattern drives sexual selection and not vice versa. Longer-term simulations exhibit rapid switches between alternative parental care patterns, even in constant environments. Hence, the evolutionary lability of sex roles observed in phylogenetic studies is not necessarily caused by external changes. Overall, our findings are in striking contrast to the predictions of mathematical models. We show that the discrepancies are caused by transient within-sex polymorphisms in parental strategies, a factor largely neglected in current sex-role theory.

Parental care in male degus (Octodon degus) is flexible and contingent upon female care

Adaptive Male Parental Care in the Giant Bullfrog, Pyxicephalus adspersus

This study was aimed towards detecting how perceived parenting practices before adolescence affect maternal-infant bonding in the perinatal period, considering factors such as depression, anxiety, and parity. We used the Parental Bonding Instrument (PBI) to examine perceived parenting practices. Participants included 1301 pregnant women who completed the Hospital Anxiety and Depression Scale (HADS) and Mother-to-Infant Bonding Scale (MIBS) at three time points: early pregnancy (approximately 12-15 weeks), late pregnancy (approximately 30-34 weeks) and postpartum (4 weeks after childbirth). We performed a path analysis with factors including parity, PBI subscales (paternal care, paternal overprotection, maternal care and maternal overprotection), HADS and MIBS. Perceived paternal or maternal low care parenting predicted higher HADS and MIBS scores in early pregnancy. Moreover, perceived maternal low care parenting predicted higher HADS scores at postpartum and higher MIBS scores in late pregnancy. Perceived paternal or maternal overprotective parenting predicted higher HADS scores in the pregnancy period. Furthermore, perceived maternal overprotective parenting predicted higher MIBS scores in late pregnancy. Being primipara predicted higher HADS scores at postpartum and higher MIBS scores in early pregnancy and at postpartum. Being multipara predicted higher MIBS scores in late pregnancy. This study suggests that perceived negative parenting before adolescence has indirect effects (via anxiety and depression) and direct effects on maternal-infant bonding in the perinatal period.

BackgroundCertainty of paternity is considered an important factor in the evolution of paternal care. Several meta-analyses across birds support this idea, particularly for species with altricial young. However, the role of certainty of paternity in the evolution and maintenance of exclusive paternal care in the black coucal (Centropus grillii), which is the only known altricial bird species with male-only care, is not well understood. Here we investigated whether the differences in levels of paternal care in the black coucal and its sympatric congener, the bi-parental white-browed coucal (Centropus superciliosus), are shaped by extra-pair paternity.ResultsWe found that male black coucals experienced a substantially higher loss of paternity than white-browed coucals. Further, unlike any previously reported bird species, extra-pair offspring in black coucals represented mainly the last hatchlings of the broods, and these last hatchlings were more likely to disappear during partial-brood loss.ConclusionThe results suggest that exclusive paternal care in black coucals is not maintained by male certainty of parentage, and extra-pair fertilizations are unlikely to be a female strategy for seeking ‘good genes’. Extra-pair paternity in black coucals may reflect the inability of males to guard and copulate with the female after the onset of incubation, and a female strategy to demonstrate her commitment to other males of her social group.