Benefits and costs of female and male care in amphibians: a meta-analytical approach.

The origin of parental care is a central question in evolutionary biology, and understating the evolution of this behaviour requires quantifying benefits and costs. To address this subject, we conducted a meta-analysis on amphibians, a group in which parental care has evolved multiple times. We found that both male and female parents increase egg survival, regardless of whether the breeding site is concealed or exposed. Parental care also increases survival and growth of tadpoles and juveniles, independent of the caring sex. However, parental care reduces parental body condition, particularly when parents remain stationary near the offspring. Females tend to experience higher reproductive costs, but sample size is restricted to few species. In some frog species, paternal care increases male reproductive success because females prefer caring males. The benefits of parental care in amphibians resembles those reported for arthropods but differ from fish, in which parental care does not improve offspring survival. Moreover, the decrease in body condition, which is not found in fish, is influenced by the form of parental care, suggesting a trade-off between caring and foraging, as already reported for certain arthropods. Finally, the reproductive costs of parental care for both sexes remain unexplored and deserve further research.

Parental Behavior in Carnivores.

The mammalian order Carnivora is generally defined as species that feed exclusively or to some degree by eating other animals. The Carnivora comprise around 280 species, divided into 16 families, 13 of which are terrestrial and 3 aquatic. Carnivores are spread across the entire planet, including the two polar regions and on land and sea. Consistent with such diverse ecologies, there is no typical pattern of parental care distinguishing carnivores from other mammals. Using examples from different taxonomic families, our aim is to illustrate the diversity of parental care in Carnivora. Major topics include parental care before and after birth of the young, paternal, and alloparental care and the process of weaning. Given the position of many carnivores at the apex of food chains, a greater understanding of their patterns of parental care as a vital part of reproductive biology is essential to conservation programs.

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

Parents in many animal species provide care to their offspring as a mechanism to enhance their own fitness. In mammals, this behavior is expressed mostly by the females, but also by males of some species. Proximally, rates of paternal offspring care have been linked to organizational and activational effects of testosterone. Specifically, intrauterine position of male fetuses is associated with differential exposure to testosterone, leading to development of males with different levels of masculinization (assessed through differences in the length of the anogenital distance (AGD). The relative roles played by organizational and activational effects of testosterone on male parental care remain unclear. In this study, we aimed to determine if male sex-biased uterine environment and testosterone levels across the breeding period explain variation in paternal care in the social rodent, Octodon degus. Neither quantity (time with the offspring) nor quality (frequency of grooming and retrieving) of paternal care was affected by male sex-biased uterine environment, nor did paternal care significantly differ across the different stages of male reproduction. In contrast, paternal care was associated with maternal care. Quantity of male care decreased with increasing quantity of maternal care, and quality of male care increased with increasing quality of maternal care. While serum testosterone did not differ between males with different sex-biased uterine environment, male testosterone tended to increase during mating and decrease when pregnant females or offspring were present.

Functional New World monkey oxytocin forms elicit an altered signaling profile and promotes parental care in rats.

The neurohormone oxytocin is a key player in the modulation of reproductive and social behavioral traits, such as parental care. Recently, a correlation between different forms of oxytocin and behavioral phenotypes has been described in the New World Monkeys (NWMs). Here, we demonstrate that, compared with the Leu8OXT found in most placental mammals, the Cebidae Pro8OXT and Saguinus Val3Pro8OXT taxon-specific variants act as equi-efficacious agonists for the Gq-dependent pathway but are weaker agonists for the ß-arrestin engagement and subsequent endocytosis toward the oxytocin receptor (OXTR). Upon interaction with the AVPR1a, Pro8OXT and the common Leu8OXT yielded similar signaling profiles, being equally efficacious on Gq and ß-arrestin, while Val3Pro8OXT showed reduced relative efficacy toward ß-arrestin. Intranasal treatment with either of the variants increased maternal behavior and also promoted unusual paternal care in rats, as measured by pup-retrieval tests. We therefore suggest that Val3Pro8OXT and Pro8OXT are functional variants, which might have been evolutionarily co-opted as an essential part of the adaptive genetic repertoire that allowed the emergence of taxon-specific complex social behaviors, such as intense parental care in the Cebidae and the genus Saguinus.

Devoted fathers or selfish lovers? Conflict between mating effort and parental care in a harem-defending arachnid.

When there is a temporal trade-off between mating effort and parental care, theoretical models predict that intense sexual selection on males leads to reduced paternal care. Thus, high-quality males should invest more in mating effort because they have higher chances of acquiring mates, whereas low-quality males should bias their investment towards parental care. Once paternal care has evolved, offspring value should also influence males' decisions to invest in offspring attendance. Here, we performed a manipulation under field conditions to investigate the factors that influence male allocation in either mating effort or parental care. We predicted that facultative paternal care in the harem-holding harvestman Serracutisoma proximum would be negatively influenced by male attractiveness and positively influenced by offspring value. We found that attractive males were less likely to engage in egg attendance and that the higher the perceived paternity, the higher the caring frequency. Finally, egg mortality was not related to caring frequency by males, but predation pressure was much lower than that recorded in previous studies with the same population. Thus, the benefits of facultative male care may be conditional to temporal variation in the intensity of egg predation. In conclusion, males adjust their investment in either territory defence or egg attendance according to their recent mating history and perceived paternity. Our findings suggest that exclusive paternal care can evolve from facultative paternal care only if the trade-off between mating effort and parental care is circumvented.

The state of art of biological processes in paternal care / Processos biológicos na paternidade: estado de arte

This review of the state of art aimed to present the most recent data on neuronal, neurochemical, hormonal and genetic bases of paternal care using MEDLINE and PsycInfo databases (1970-2013). An integrated model of biological substrates that assist men in the transition to fatherhood is presented. Guided by a genetic background, hypothalamic-midbrain-limbic-paralimbic-cortical circuits were found to be activated in fathers when infant stimuli are presented. A set of specific neuropeptides and steroid hormones are produced and seem to be related to brain activation, potentiating the paternal phenotype. Together, genetic, brain and hormonal processes suggest the existence of biological bases of paternal care in humans, activated and enhanced by infant stimuli and responsive to variations in the father-infant relationship. (AU)

A presente revisão teve por objectivo apresentar o estado de arte dos dados mais recentes sobre as bases neuronais, neuroquímicas, hormonais e genéticas da paternidade, com recurso às bases de dados MEDLINE e PsycInfo (1970-2013). É apresentado um modelo de integração conceptual dos substratos biológicos que assistem os homens na transição para a parentalidade. Guiado por um background genético, circuitos neuronais hipotalámicos-mesencefálicos-límbicos-paralímbicos-corticais surgem ativados em pais quando lhes são apresentados estímulos infantís. Um conjunto de neuropéptidos e hormonas esteróides são também produzidos e relacionam-se com a activação neuronal, potenciando o fenótipo paternal. No seu conjunto, processos genéticos, neuronais e hormonais sugerem a existência de uma base biológica do comportamento paternal em humanos, activada e potenciada por estímulos infantís e responsiva a variações na relação pai-filho. (AU)

Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys.

Understanding the evolution of mating systems, a central topic in evolutionary biology for more than 50 years, requires examining the genetic consequences of mating and the relationships between social systems and mating systems. Among pair-living mammals, where genetic monogamy is extremely rare, the extent of extra-group paternity rates has been associated with male participation in infant care, strength of the pair bond and length of the breeding season. This study evaluated the relationship between two of those factors and the genetic mating system of socially monogamous mammals, testing predictions that male care and strength of pair bond would be negatively correlated with rates of extra-pair paternity (EPP). Autosomal microsatellite analyses provide evidence for genetic monogamy in a pair-living primate with bi-parental care, the Azara's owl monkey (Aotus azarae). A phylogenetically corrected generalized least square analysis was used to relate male care and strength of the pair bond to their genetic mating system (i.e. proportions of EPP) in 15 socially monogamous mammalian species. The intensity of male care was correlated with EPP rates in mammals, while strength of pair bond failed to reach statistical significance. Our analyses show that, once social monogamy has evolved, paternal care, and potentially also close bonds, may facilitate the evolution of genetic monogamy.