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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 ensur...
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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.
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An incipient termite colony initially functions as a biparental family unit. The emergence of the first workers initiates the transition from biparental to alloparental care within a colony. During this transition, the number of p...
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An incipient termite colony initially functions as a biparental family unit. The emergence of the first workers initiates the transition from biparental to alloparental care within a colony. During this transition, the number of protozoa harbored by Reticulitermes speratus (Kolbe) kings and queens is dynamic. In Coptotermes gestroi (Wasmann), the transition to alloparental care is completed by 150 days after colony foundation. In the present study, we quantified the protozoan abundance of C. gestroi and Coptotermes formosanus Shiraki kings and queens at ten time points during the transition from biparental to alloparental care (0-400 days post colony foundation). The protozoan abundance of C. gestroi and C. formosanus kings and queens peaked on either day 35 or 60 during the biparental care period, and then progressively decreased during the remainder of the study. By day 400 the protozoan abundance of kings and queens was either similar to or less than the abundance observed within unmated dealates. Both C. gestroi and C. formosanus kings and queens still harbored protozoa at day 150 even though the transition to alloparental care was completed by this time. On days 250 and 400 for C. formosanus, and on day 400 for C. gestroi, the protozoan abundance of kings was greater than the abundance of queens. These results indicate that alloparental care can become set within a colony prior to the loss of protozoa within the royal pair, and that queens lose their protozoa earlier than kings during incipient colony development.
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Allonursing, the nursing of nonoffspring, is a form of cooperative breeding. To test the kin-selection allonursing hypothesis, we selected 2 experimental groups, based on genetic relatedness, to assess whether evidence of individu...
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Allonursing, the nursing of nonoffspring, is a form of cooperative breeding. To test the kin-selection allonursing hypothesis, we selected 2 experimental groups, based on genetic relatedness, to assess whether evidence of individual and daily patterns of kin-related allonursing would emerge. Each group consisted of 8 motheroffspring pairs, and observers monitored each group over 5 weeks, starting when the offspring were between 8 and 23 days old. One group of 8 mothers was selected to be closely related, and the other group of 8 mothers was selected to be distantly related, based on genetic relatedness. We recorded 1,652 solicitations, of which 869 were nursing bouts and 161 were allonursing bouts. All mothers nursed their own offspring, and 15 of the 16 mothers allonursed. In both groups, 7 of the 8 offspring were allonursed. The offspring of closely related mothers were allonursed more often than the offspring of distantly related mothers, and we found evidence for this pattern at the individual level and daily over 5 weeks. Our results supported the kin-selection hypothesis but not the compensation hypothesis. We suggest that allonursing may have provided adaptive and nutritional benefits related to kin selection, and offspring from the closely related group may have gained more nutritional benefits and more mass than offspring from the distantly related group. We presented evidence that allonursing contributions detected can depend upon the research design. Furthermore, we suggest that the indirect fitness benefits of alloparental care may have been overestimated, and that kin selection alone is not sufficient to explain alloparental care in cooperative breeding social systems.
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Oxytocin modulates many aspects of social cognition and behaviors, including maternal nurturing, social recognition and bonding. Natural variation in oxytocin receptor (OXTR) density in the nucleus accumbens (NAcc) is associated w...
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Oxytocin modulates many aspects of social cognition and behaviors, including maternal nurturing, social recognition and bonding. Natural variation in oxytocin receptor (OXTR) density in the nucleus accumbens (NAcc) is associated with variation in alloparental behavior, and artificially enhancing OXTR expression in the NAcc enhances alloparental behavior and pair bonding in socially monogamous prairie voles. Furthermore, infusion of an OXTR antagonist into the NAcc inhibits alloparental behavior and partner preference formation. However, antagonists can promiscuously interact with other neuropeptide receptors. To directly examine the role of OXTR signaling in social bonding, we used RNA interference to selectively knockdown, but not eliminate, OXTR in the NAcc of female prairie voles and examined the impact on social behaviors. Using an adeno-associated viral vector expressing a short hairpin RNA (shRNA) targeting Oxtr mRNA, we reduced accumbal OXTR density in female prairie voles from juvenile age through adulthood. Females receiving the shRNA vector displayed a significant reduction in alloparental behavior and disrupted partner preference formation. These are the first direct demonstrations that OXTR plays a critical role in alloparental behavior and adult social attachment, and suggest that natural variation in OXTR expression in this region alone can create variation in social behavior.
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We aimed to elucidate the factors that influence the frequency of adoption and infanticide in the Blue-footed Booby (Sula nebouxii), a seabird with biparental chick care and high chick-rearing costs. We obtained data from two colo...
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We aimed to elucidate the factors that influence the frequency of adoption and infanticide in the Blue-footed Booby (Sula nebouxii), a seabird with biparental chick care and high chick-rearing costs. We obtained data from two colonies during four breeding seasons. In addition, we removed parents from their nests for short periods of time (10 min) and fitted their chicks with polyethylene foam protectors, in order to record chick behavior, particularly interactions with neighboring adults. Adoption and infanticide occurred mostly in zones of high nest density and during years of high breeding success. The chicks adopted were 20-40 days of age, the age at which they acquire mobility and parents still experience a certain inability to recognize them. Adopted chicks were slightly younger than chicks in the broods into which they were adopted. In most cases, adoptees were younger than their siblings in their natal broods. We also recorded short-term (lasting only a few hours) alloparental care for chicks older than 40 days. When we excluded parents from nests and their chicks were attacked, it was female neighbors that physically attacked them, whereas males were more prone to brood or preen them; therefore, the sex with certainty of parenthood was more prone to practice infanticide, presumably to avoid adoption. The lack of aggressiveness by males might be due to the possibility of paternity, given the occurrence of extra-pair copulations in this species.
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This study describes allonursing (females nursing offspring that are not their own) in captive belugas (Delphinapterus leucas). In addition to the calf's mother, two females that were not pregnant or nursing at the time of the cal...
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This study describes allonursing (females nursing offspring that are not their own) in captive belugas (Delphinapterus leucas). In addition to the calf's mother, two females that were not pregnant or nursing at the time of the calf's birth spontaneously lactated and nursed the male calf intermittently throughout 34 months of his life at the Vancouver Aquarium Marine Science Center. These observations suggest that allonursing may also take place in their wild counterparts and add to existing evidence of alloparental care in this species. Alloparental care, the care of nonoffspring, has been observed in every major mammalian taxon; the protection of calves through alloparental care may be a strong evolutionary benefit.
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This study describes allonursing (females nursing offspring that are not their own) in captive belugas (Delphinapterus leucas). In addition to the calf's mother, two females that were not pregnant or nursing at the time of the cal...
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This study describes allonursing (females nursing offspring that are not their own) in captive belugas (Delphinapterus leucas). In addition to the calf's mother, two females that were not pregnant or nursing at the time of the calf's birth spontaneously lactated and nursed the male calf intermittently throughout 34 months of his life at the Vancouver Aquarium Marine Science Center. These observations suggest that allonursing may also take place in their wild counterparts and add to existing evidence of alloparental care in this species. Alloparental care, the care of nonoffspring, has been observed in every major mammalian taxon; the protection of calves through alloparental care may be a strong evolutionary benefit.
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Humans have been called "cooperative breeders" because mothers rely heavily on alloparental assistance, and the grandmother life stage has been interpreted as an adaptation for alloparenting. Many studies indicate that women inves...
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Humans have been called "cooperative breeders" because mothers rely heavily on alloparental assistance, and the grandmother life stage has been interpreted as an adaptation for alloparenting. Many studies indicate that women invest preferentially in their daughters' children, but little research has been conducted where patrilocal residence is normative. Bangladesh is such a place, but women nevertheless receive substantial alloparental investment from the matrilateral family, and child outcomes improve when maternal grandmothers are alloparents. To garner this support, women must maintain contact with their natal families. Here, the visiting behavior of 151 interviewed mothers was analyzed. Despite the challenges of patrilocality and purdah, almost all respondents visited their own mothers, and mothers-in-law were visited far less. This contrast persists in analyses controlling for proximity, respondent age, postmarital residence, family income, and marital status. These results affirm the importance women place on matrilateral ties, even under a countervailing ideology.
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Capsule Adoptions occurred at low rate (2.6% of successful nests and 1.1% of fledglings), probably as a result of a mistake in early offspring recognition.
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