The unusual food provisioning by males beyond mating in the spider Manogea porracea (Araneidae)

Life history theory predicts that iteroparous animals adaptively partition reproductive effort between current and future reproduction. When rearing costs of current offspring exceed the potential benefits, parental care should be terminated and deferred toward future reproduction. We tested two related predictions that follow from life history theory: (a) parents should be sensitive to offspring viability and withhold parental care if offspring survival probability drops and future reproductive opportunities are likely, and (b) parents should be less sensitive to offspring survival probability when future reproduction is unlikely and maximize parental care late in life. The wolf spider,Pardosa milvina, demonstrates extensive parental care; however, they may also abandon or cannibalize their egg sacs. We tested the effects of egg sac damage and production of a previous egg sac on egg sac abandonment and cannibalism decisions. Among four egg sac groups (1st egg sac intact, 1st egg sac damaged, 2nd egg sac intact, 2nd egg sac damaged), we daily monitored egg sac abandonment and cannibalism and measured differences in egg sac searching, protection, and grooming among removed and damaged egg sacs (N = 116 with 1st egg sac and 88 with 2nd egg sac). Females with first egg sacs abandoned and cannibalized damaged egg sacs significantly more compared to unmanipulated egg sacs; however, females with second egg sacs were insensitive to egg sac damage. Females also spent significantly more time protecting second egg sacs compared to first egg sacs and groomed damaged egg sacs significantly more than undamaged. These results support the general predictions of life history theory that indicate that abandonment and cannibalism should decrease with diminished future reproductive potential and that parents should be less sensitive to indicators of offspring survival probability late in life.

Male-female social interactions may vary according to female receptivity, female parity, and male dominance rank. Such variation may be less apparent in species with one-male mating systems than those with multimale mating systems, as within-group male-male competition and female mate choice are absent. Examining variation in male-female interactions in multimale groups in species with a predominantly one-male mating system may help to shed light on plasticity in behavioral patterns and the evolution of mating systems. In this study, we investigated the effect of female receptivity (i.e., days when mating occurred), female parity, and male dominance rank on the patterns of spatial proximity, grooming, following, and aggression among 34 male-female dyads in four multi-male groups of Virunga mountain gorillas. In addition, as a preliminary investigation of potential physiological costs incurred by females in a mating context (coercion), we tested whether female receptivity and female parity explained variation in immunoreactive glucocorticoid (iGC) levels of females. The amount of time male-female dyads spent in close proximity was significantly higher for parous versus nulliparous females and for high- versus low-ranking males. The rate of male aggression to females did not vary significantly with female parity, male rank, or female receptivity. However, post hoc analysis showed that both proximity and aggression increased for the males that participated in the matings on days that females were receptive. Grooming and following by males occurred infrequently. Neither female receptivity nor parity influenced iGC levels in females, a finding that is more consistent with courtship than coercion of females by males. Overall, our results suggest that males advertise their ability to provide protection to females and their offspring, and females seek out males that can do so.

Background. Geographic variation in body size and condition can reveal differential local adaptation to resource availability or climatic factors. Body size and condition are related to fitness in garter snakes (Thamnophis), thus good body condition may increase survival, fecundity in females, and mating success in males. Sympatric species are predicted to exhibit similar body condition when they experience similar environmental conditions. We focused on interspecific and geographical variation in body size and condition in three sympatric Mexican garter snakes from the highlands of Central Mexico. Methods. We assessed SVL, mass, and body condition (obtained from Major axis linear regression of ln-transformed body mass on ln-transformed SVL) in adults and juveniles of both sexes of Thamnophis eques, T. melanogaster, and T. scalaris sampled at different locations and over a 20-year period. Results. We provide a heterogeneous pattern of sexual and ontogenic reproductive status variations of body size and condition among local populations. Each garter snake species shows locations with good and poor body condition; juvenile snakes show similar body condition between populations, adults show varying body condition between populations, and adults also show sexual differences in body condition. We discuss variations in body condition as possibly related to the snakes’ life cycle differences.

BackgroundGeographic variation in body size and condition can reveal differential local adaptation to resource availability or climatic factors. Body size and condition are related to fitness in garter snakes (Thamnophis), thus good body condition may increase survival, fecundity in females, and mating success in males. Phylogenetically related species in sympatry are predicted to exhibit similar body condition when they experience similar environmental conditions. We focused on interspecific and geographical variation in body size and condition in three sympatric Mexican garter snakes from the highlands of Central Mexico.MethodsWe assessed SVL, mass, and body condition (obtained from Major axis linear regression of ln-transformed body mass on ln-transformed SVL) in adults and juveniles of both sexes of Thamnophis eques, T. melanogaster, and T. scalaris sampled at different locations and ranges from 3–11 years over a 20-year period.ResultsWe provide a heterogeneous pattern of sexual and ontogenic reproductive status variations of body size and condition among local populations. Each garter snake species shows locations with good and poor body condition; juvenile snakes show similar body condition between populations, adults show varying body condition between populations, and adults also show sex differences in body condition. We discuss variations in body condition as possibly related to the snakes’ life cycle differences.

Interindividual variation in fecundities has major consequences on population evolutionary potential, through genetic drift and selection. Using two spatially explicit mating models that analyse the genotypes of seeds and seedlings, we investigated the variation of male and female fecundities within and among three European beech (Fagus sylvatica) stands situated along an altitudinal gradient. Female and male individual fecundity distributions were both skewed in this monoecious species, and we found a higher variance in female as compared to male fecundities. Both female and male fecundities increased with tree size and decreased with density and competition in the neighbourhood, the details of these effects suggesting sex-specific strategies to deal with the impact of limited resource on fecundity. The studied populations were functionally male-biased. Among-individual variations in functional gender were not driven by tree size but by density and competition in the neighbourhood. Femaleness decreased under limited resource availability, an expected consequence of the higher cost of female reproduction. Considering the variation of gene flow and genetic drift across elevation, our results suggest that the adaptive potential could be enhanced by low genetic drift at low elevation, and by high pollen-mediated gene flow at high elevation. Finally, this study predicts a more efficient response to selection for traits related to male vs. female fitness, for a given selection intensity.

Many animals provide parental care to increase the success of offspring. Parental behaviors can be costly, and should only be directed toward related young. Offspring recognition and differential effort are ways that animals ensure that care is directed toward related individuals. Pardosa milvina is a small wolf spider that provides parental care for their young, carrying first their egg sac and later their spiderlings. This species is known to pick up abandoned egg sacs. We conducted a study to determine whether female P. milvina differentiated between her own egg sac and a conspecific's egg sac and whether there was a benefit to spiderlings in being raised by their biological mother, and whether age, when removed from the mother, influenced the outcome. In one experiment, we removed the egg sac from a female and gave her a choice of items to reattach: their own egg sac, another spider's egg sac, or a plastic bead. Females were more likely to pick up their own egg sac than another spider's. In another experiment, we removed a female spider's egg sac either 1 day or 7 days after the eggs were produced and gave them either their own egg sac or another spider's egg sac to care for. We measured hatching success and offspring survival. Spiders manipulated after 7 days were more likely to be abandoned as eggs, whether cared for by their biological mother, and reached adulthood less often. However, cross‐fostering had no effect on spiderling success whether the transfer occurred after 1 day. Our data showed that P. milvina can recognize their own egg sac, but there was no evidence of differential parental care provided to the biological offspring.

Temperature impacts behaviour, physiology and life-history of many life forms. In many ectotherms, phenotypic plasticity within reproductive traits could act as a buffer allowing adaptation to continued global warming within biological limits. But there could be costs involved, potentially affecting adult reproductive performance and population growth. Empirical data on the expression of reproductive plasticity when different life stages are exposed is still lacking. Plasticity in key components of fitness (e.g., reproduction) can impose life-history trade-offs. Ectotherms are sensitive to temperature variation and the resulting thermal stress is known to impact reproduction. So far, research on reproductive plasticity to temperature variation in this species has focused on males. Here, I explore how rearing temperature impacted female reproduction and lifespan in the bruchid beetle Callosobruchus maculatus by exposing them to four constant temperatures (17 °C, 25 °C, 27 °C and 33 °C) during larval or adult stages. In these experiments, larval rearing cohorts (exposed to 17 °C, 25 °C, 27 °C and 33 °C, from egg to adulthood) were tested in a common garden setting at 27 °C and adult rearing cohorts, after having developed entirely at 27 °C, were exposed to four constant rearing temperatures (17 °C, 25 °C, 27 °C and 33 °C). I found stage-specific plasticity in all the traits measured here: fecundity, egg morphological dimensions (length and width), lifespan and egg hatching success (female fertility). Under different larval rearing conditions, fecundity and fertility was drastically reduced (by 51% and 42%) at 17 °C compared to controls (27 °C). Female lifespan was longest at 17 °C across both larval and adult rearing: by 36% and 55% compared to controls. Collectively, these results indicate that larval rearing temperature had greater reproductive impacts. Integrating both larval and adult rearing effects, I present evidence that female fertility is more sensitive during larval development compared to adult rearing temperature in this system.

The modulation of longevity genes and aging-associated signaling pathways using pharmacological agents is one of the potential ways to prolong the lifespan and increase the vitality of an organism. Phytochemicals flavonoids and non-steroidal anti-inflammatory drugs have a large potential as geroprotectors. The goal of the present study was to investigate the effects of long-term and short-term consumption of quercetin, (-)-epicatechin, and ibuprofen on the lifespan, resistance to stress factors (paraquat, hyperthermia, γ-radiation, and starvation), as well as age-dependent physiological parameters (locomotor activity and fecundity) of Drosophila melanogaster. The long-term treatment with quercetin and (-)-epicatechin didn't change or decreased the lifespan of males and females. In contrast, the short-term treatment with flavonoids had a beneficial effect and stimulated the resistance to paraquat and acute γ-irradiation. The short-term ibuprofen consumption had a positive effect on the lifespan of females when it was carried out at the middle age (30–40 days), and to the survival of flies under conditions of oxidative and genotoxic stresses. However, it didn't change the lifespan of males and females after the treatment during first 10 days of an imago life. Additionally, quercetin, (-)-epicatechin, and ibuprofen decreased the spontaneous locomotor activity of males, but had no effect of stimulated the physical activity and fecundity of females. Revealed quercetin, (-)-epicatechin, and ibuprofen activity can be associated with the stimulation of stress response mechanisms through the activation of pro-longevity pathways, or the induction of hormesis.

Parental care is a trait present in many animals, increasing the offspring survival with the reduction of the mortality caused by biotic and abiotic factors. In spiders, parental care is quite diverse, being frequently efficient against some generalist predators, such as ants. For birds and other visually orientated predators, spiders have various strategies against predation, like camouflage and disguises (“masquerade”). However, some groups of predators and parasitoids (e.g. wasps, dipterans and mantispids) have species capable of surpassing the multiple lines of defense and attack the eggs of spiders. Still, little is known about the occurrence and impact of these natural enemies on offspring survival of spiders, and what potential effect parental care in this context. Thus, in this thesis we investigate the behavioral ecology of spiders from the families Araneidae and Uloboridae and their eggs, describing the natural enemies of each studied species. We demonstrate that parental care in Manogea porracea (Araneidae) is efficient for the survival of the eggs in a population on Cerrado, even in the presence of an egg predator that had not been described previously attacking the species. We investigated maternal care in the spider Miagrammopes unipus (Uloboridae) describing its behavior with the egg sacs, the variation in the egg sacs and the attack of the eggs by a parasitoid wasp. We also investigated camouflage in this species through the calculation of background matching between females, their egg sacs and substrates used to rest. We registered the insects associated with the egg sacs of 10 species of spiders, including the two previously mentioned. Only one species was not attacked by any natural enemy, the invasive spider Cyrtophora citricola (Araneidae), recently found in Brazil. All other nine species were attacked by some egg predator or parasitoids, such as wasps, diptera and mantispids. Finally, we describe a parasitoid wasp of the spiders attacking C. citricola, showing the use of a new host for a native wasp, but still without any records of predators or parasitoids attacking their egg sacs in the population studied. Many interactions between the spiders, their egg sacs and natural enemies were explored in this thesis, contributing to the understanding of the ecology and evolution of these animals.

Korean adults have traditionally anticipated providing care to their aging parents, while also hoping their own children will reciprocate similar care when needed. However, as family care norms have weakened, people’s expectations about care are in flux—some anticipate family care, some expect formal care (e.g., nursing homes or professional care workers), while others have no clear expectation about care. Further, people may have different expectations between care for aging parents and their own future care. This study examined middle-aged adults’ expectations about (a) care for parents and (b) their own future care (i.e., family care, formal care, or uncertain) and how combinations of these care expectations were related to aging anxiety. Using data from 2014 Korean Baby Boomer Panel Study, we analyzed a sample of middle-aged adults (N = 1,748; aged 51–59), who have at least one living parent and one living child. We found that 36% expected family care for parents but formal care for themselves, followed by expecting formal care for both (32%). Expecting formal care for parents but family care for oneself was least common (1%), while expecting family care for both was also rare (6%). Additionally, 24% indicated uncertain expectations about either or both. Regression analyses revealed that individuals who expected formal care for both or who had no clear expectations experienced greater aging anxiety than those expecting family care for both. These findings highlight the importance of planning for aging parents’ and own future care needs in the context of changing care norms.

Don't put all your eggs in small baskets: Ineffective guardians, incidence of parasitoids and clutch size of Latrodectus geometricus (Araneae, Theridiidae) along an urban gradient

Courtship feeding in tree crickets increases insemination and female reproductive life span

According to sexual selection theory, females choose mates to ensure access to high quality resources, male parental care, or good genes. This last hypothesis has been hotly debated on both theoretical and empirical grounds. In contrast, female preference for male parental care has received less attention, primarily because the potential benefits of paternal effort seem obvious. The fitness relations are less clear in double-brood species, however, because females can base mating decisions on their prior experience with male parental care. Here, the extent of male parental care delivered to first-brood offspring may indicate male genetic quality and/or be the target of female manipulation via her subsequent mating fidelity. In Savannah Sparrows (Passerculus sandwichensis), multi-locus DNA fingerprinting of 203 adults and young revealed substantial female infidelity in first and second broods: overall, 24 of 80 first-brood young (30%) and 13 of 80 second-brood young (16.3%) were the product of extra-pair fertilizations. Among 12 females altering fidelity between broods, absolute male feeding rate to first-brood offspring was a strong, positive predictor of change in female fidelity. Because the extent of male parental care reflects a male's viability, the data support a 'good-genes' interpretation.

A pheromone receptor in cichlid fish mediates attraction to females but inhibits male parental care

The expressions of parental care can vary in space and time because factors driving offspring mortality depend on variable abiotic and biotic conditions. Manogea porracea is a spider that exhibits biparental care and widespread distribution in the Neotropical region. Parents can protect their offspring against abiotic conditions that may damage their webs, or compromise their egg sacs, and against araneophagic spiders that prey on their eggs. However, the current knowledge of the parental care in the species is restricted to a population located in areas covered by Eucalyptus plantations. This study investigates parental care efficiency in a new ecological context, a protected area of Brazilian savanna. We described the substrates in which M. porracea built webs and the agents of egg mortality. We also performed a parent removal experiment to test the effect of parental care on the integrity of nursery webs, offspring survival, and the presence of egg predators. Spiders built webs at variable heights and many distinct substrates but were mainly associated with the bromeliad Ananas ananassoides. We found two previously reported egg predators, Faiditus caudatus and Argyrodes elevatus (Araneae Theridiidae), and a new one emerging from the egg sacs, the insect Zeugomantispa virescens (Neuroptera Mantispidae). The presence of parents in the webs of M. porracea prevented the webs from collapsing and effectively increased offspring survival. However, the occurrence of egg predators was not reduced by the presence of parents. Overall, parental care increased offspring survival in both populations, but variation in biotic and abiotic factors between areas influenced offspring mortality and the efficiency of parental behaviours. Our results emphasise the importance of investigating multiple populations in behavioural studies of parental care.