scholarly journals Experimental evidence that chronic outgroup conflict reduces reproductive success in a cooperatively breeding fish

2021 ◽  
Author(s):  
Ines Braga Goncalves ◽  
Andy Radford
Keyword(s):  
Reproductive Success ◽  
Experimental Evidence ◽  
Social Evolution ◽  
Group Living ◽  
Reproductive Investment ◽  
Empirical Literature ◽  
Control Groups ◽  
Cooperatively Breeding ◽  
Consistent Group ◽  
Defence Behaviour

Conflicts with conspecific outsiders are common in group-living species, from ants to primates, and are argued to be an important selective force in social evolution. However, whilst an extensive empirical literature exists on the behaviour exhibited during and immediately after interactions with rivals, only very few observational studies have considered the cumulative fitness consequences of outgroup conflict. Using a cooperatively breeding fish, the daffodil cichlid (Neolamprologus pulcher), we conducted the first experimental test of the effects of chronic outgroup conflict on reproductive investment and output. ‘Intruded’ groups received long-term simulated territorial intrusions by neighbours that generated consistent group-defence behaviour; matched ‘Control’ groups (each the same size and with the same neighbours as an Intruded group) received no intrusions in the same period. Intruded groups had longer inter-clutch intervals and produced eggs with less protein than Control groups. Despite this lower egg investment, Intruded groups provided more parental care, achieving similar hatching success to Control groups. Ultimately, however, Intruded groups had fewer and smaller surviving offspring than Control groups at 1-month post-hatching. We therefore provide experimental evidence that outgroup conflict can decrease fitness via cumulative effects on reproductive success, confirming the selective potential of this empirically neglected aspect of sociality.

Social status influences responses to unfamiliar conspecifics in a cooperatively breeding fish

Behaviour ◽  
2015 ◽  
Vol 152 (12-13) ◽  
pp. 1821-1839 ◽  
Author(s):  
Isaac Y. Ligocki ◽  
Adam R. Reddon ◽  
Jennifer K. Hellmann ◽  
Constance M. O’Connor ◽  
Susan Marsh-Rollo ◽  
...  
Keyword(s):  
Social Status ◽  
Cichlid Fish ◽  
Group Living ◽  
Costs And Benefits ◽  
Control Groups ◽  
High Ranking ◽  
The Social ◽  
Cooperatively Breeding ◽  
Group Members ◽  
Group Member

In group living animals, individuals may visit other groups. The costs and benefits of such visits for the members of a group will depend on the attributes and intentions of the visitor, and the social status of responding group members. Using wild groups of the cooperatively breeding cichlid fish (Neolamprologus pulcher), we compared group member responses to unfamiliar ‘visiting’ conspecifics in control groups and in experimentally manipulated groups from which a subordinate the same size and sex as the visitor was removed. High-ranking fish were less aggressive towards visitors in removal groups than in control groups; low-ranking subordinates were more aggressive in the removal treatment. High-ranking females and subordinates the same size and sex as the visitor responded most aggressively toward the visitor in control groups. These results suggest that visitors are perceived as potential group joiners, and that such visits impose different costs and benefits on current group members.

scholarly journals Isotocin neuronal phenotypes differ among social systems in cichlid fishes

2017 ◽  
Vol 4 (5) ◽  
pp. 170350 ◽  
Author(s):  
Adam R. Reddon ◽  
Constance M. O'Connor ◽  
Erin Nesjan ◽  
Jason Cameron ◽  
Jennifer K. Hellmann ◽  
...  
Keyword(s):  
Cooperative Breeding ◽  
Social Evolution ◽  
Social Systems ◽  
Cichlid Fish ◽  
Group Living ◽  
Evolutionary Transition ◽  
Evolution Of Sociality ◽  
Cooperatively Breeding ◽  
Open Question ◽  
Complementary Analysis

Social living has evolved numerous times across a diverse array of animal taxa. An open question is how the transition to a social lifestyle has shaped, and been shaped by, the underlying neurohormonal machinery of social behaviour. The nonapeptide neurohormones, implicated in the regulation of social behaviours, are prime candidates for the neuroendocrine substrates of social evolution. Here, we examined the brains of eight cichlid fish species with divergent social systems, comparing the number and size of preoptic neurons that express the nonapeptides isotocin and vasotocin. While controlling for the influence of phylogeny and body size, we found that the highly social cooperatively breeding species ( n  = 4) had fewer parvocellular isotocin neurons than the less social independently breeding species ( n  = 4), suggesting that the evolutionary transition to group living and cooperative breeding was associated with a reduction in the number of these neurons. In a complementary analysis, we found that the size and number of isotocin neurons significantly differentiated the cooperatively breeding from the independently breeding species. Our results suggest that isotocin is related to sociality in cichlids and may provide a mechanistic substrate for the evolution of sociality.

scholarly journals The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder

2015 ◽  
Vol 282 (1819) ◽  
pp. 20152031 ◽  
Author(s):  
Dominic L. Cram ◽  
Jonathan D. Blount ◽  
Andrew J. Young
Keyword(s):  
Experimental Evidence ◽  
Body Mass ◽  
Group Size ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Costs Of Reproduction ◽  
Breeding Bird ◽  
Reduced Body ◽  
Cooperatively Breeding ◽  
In The Wild

Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali . Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies.

scholarly journals Sperm modulate uterine immune parameters relevant to embryo implantation and reproductive success in mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
John E. Schjenken ◽  
David J. Sharkey ◽  
Ella S. Green ◽  
Hon Yeung Chan ◽  
Ricky A. Matias ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Seminal Fluid ◽  
Embryo Implantation ◽  
Reproductive Investment ◽  
Global Gene Expression ◽  
Wild Type ◽  
Mouse Uterus ◽  
Immune Parameters ◽  
Oocyte Fertilization

AbstractSeminal fluid factors modulate the female immune response at conception to facilitate embryo implantation and reproductive success. Whether sperm affect this response has not been clear. We evaluated global gene expression by microarray in the mouse uterus after mating with intact or vasectomized males. Intact males induced greater changes in gene transcription, prominently affecting pro-inflammatory cytokine and immune regulatory genes, with TLR4 signaling identified as a top-ranked upstream driver. Recruitment of neutrophils and expansion of peripheral regulatory T cells were elevated by seminal fluid of intact males. In vitro, epididymal sperm induced IL6, CXCL2, and CSF3 in uterine epithelial cells of wild-type, but not Tlr4 null females. Collectively these experiments show that sperm assist in promoting female immune tolerance by eliciting uterine cytokine expression through TLR4-dependent signaling. The findings indicate a biological role for sperm beyond oocyte fertilization, in modulating immune mechanisms involved in female control of reproductive investment.

scholarly journals Reproductive suppression in female cooperatively breeding cichlids

2008 ◽  
Vol 4 (6) ◽  
pp. 606-609 ◽  
Author(s):  
Dik Heg
Keyword(s):  
Clutch Size ◽  
Group Living ◽  
Egg Laying ◽  
Alloparental Care ◽  
Large Female ◽  
Egg Mass ◽  
Small Female ◽  
Reproductive Suppression ◽  
Cooperatively Breeding ◽  
Female Subordinate

Suppression by dominants of female subordinate reproduction has been found in many vertebrate social groups, but has rarely been shown experimentally. Here experimental evidence is provided for reproductive suppression in the group-living Lake Tanganyika cichlid Neolamprologus pulcher . Within groups of three unrelated females, suppression was due to medium- and small-sized females laying less frequently compared with large females, and compared with medium females in control pairs. Clutch size and average egg mass of all females depended on body size, but not on rank. In a second step, a large female was removed from the group and a very small female was added to keep the group size constant. The medium females immediately seized the dominant breeding position in the group and started to reproduce as frequently as control pairs, whereas clutch size and egg mass did not change. These results show that female subordinate cichlids are reproductively capable, but apparently suppressed with respect to egg laying. Nevertheless, some reproduction is tolerated, possibly to ensure continued alloparental care by subordinate females.

scholarly journals A test of male infanticide as a reproductive tactic in a cichlid fish

2017 ◽  
Vol 4 (3) ◽  
pp. 160891 ◽  
Author(s):  
Shagun Jindal ◽  
Aneesh P. H. Bose ◽  
Constance M. O'Connor ◽  
Sigal Balshine
Keyword(s):  
Cichlid Fish ◽  
Group Living ◽  
Laboratory Setting ◽  
Dominant Position ◽  
Egg Cannibalism ◽  
Cooperatively Breeding ◽  
Dominant Individual ◽  
Living Species ◽  
Reproductive Tactic ◽  
Relative Body Size

Infanticide and offspring cannibalism are taxonomically widespread phenomena. In some group-living species, a new dominant individual taking over a group can benefit from infanticide if doing so induces potential mates to become reproductively available sooner. Despite widespread observations of infanticide (i.e. egg cannibalism) among fishes, no study has investigated whether egg cannibalism occurs in fishes as a result of group takeovers, or how this type of cannibalism might be adaptive. Using the cooperatively breeding cichlid, Neolamprologus pulcher , we tested whether new unrelated males entering the dominant position in a social group were more likely to cannibalize eggs, and whether such cannibalism would shorten the interval until the female's next spawning. Females spawned again sooner if their broods were removed than if they were cared for. Egg cannibalism occurred frequently after a group takeover event, and was rarer if the original male remained with the group. While dominant breeder females were initially highly aggressive towards newcomer males that took over the group, the degree of resistance depended on relative body size differences between the new pair and, ultimately, female aggression did not prevent egg cannibalism. Egg cannibalism, however, did not shorten the duration until subsequent spawning, or increase fecundity during subsequent breeding in our laboratory setting. Our results show that infanticide as mediated through group takeovers is a taxonomically widespread behaviour.

scholarly journals Fitness of breeders in social Damaraland mole-rats is independent of group size

2021 ◽  
Author(s):  
Jack Thorley ◽  
Hanna Bensch ◽  
Kyle Finn ◽  
Tim Clutton-Brock ◽  
Markus Zöttl
Keyword(s):  
Reproductive Success ◽  
Group Size ◽  
Survival Rates ◽  
Group Living ◽  
Adult Survival ◽  
High Survival ◽  
Successful Reproduction ◽  
Related Group ◽  
Group Members ◽  
Using Data

Damaraland mole-rats (Fukomys damarensis) are usually viewed as an obligatorily group living eusocial species in which successful reproduction is dependent on reproductive altruism of closely related group members. However, the reproductive ecology of social mole-rats in their natural environment remains poorly understood and it is unclear to what extent successful reproduction is dependent on assistance from other group members. Using data from a 7-year field study of marked individuals, we show that, after dispersal from their natal group, individuals typically settled alone in new burrow systems where they enjoyed high survival rates, and often remained in good body condition for several years before finding a mate. Unlike most other eusocial or singular cooperative breeders, we found that Damaraland mole-rats reproduced successfully in pairs without helpers and experimentally formed pairs had the same reproductive success as larger established groups. Overall there was only a weak increase in reproductive success with increasing group size and no effect of group size on adult survival rates across the population. Juveniles in large groups grew faster early in life but their growth rates declined subsequently so that they eventually plateaued at a lower maximum body mass than juveniles from small groups. Taken together, our data suggest that the fitness benefits of group living to breeders are small and we suggest that extended philopatry in Damaraland mole-rats has evolved because of the high costs and constraints of dispersal rather than because of strong indirect benefits accrued through cooperative behaviour.

scholarly journals Social foraging in vampire bats is predicted by long-term cooperative relationships

2021 ◽  
Author(s):  
Simon P. Ripperger ◽  
Gerald G. Carter
Keyword(s):  
Social Evolution ◽  
Group Living ◽  
Food Sharing ◽  
Social Foraging ◽  
Social Grooming ◽  
Cooperative Relationships ◽  
Vampire Bats ◽  
In Captivity ◽  
Access To Food

AbstractStable social bonds in group-living animals can provide greater access to food. A striking example is that female vampire bats often regurgitate blood to socially bonded kin and nonkin that failed in their nightly hunt. Food-sharing relationships form via preferred associations and social grooming within roosts. However, it remains unclear whether these cooperative relationships extend beyond the roost. To evaluate if long-term cooperative relationships in vampire bats play a role in foraging, we tested if foraging encounters measured by proximity sensors could be explained by wild roosting proximity, kinship, or rates of co-feeding, social grooming, and food sharing during 22 months in captivity. We assessed evidence for six hypothetical scenarios of social foraging, ranging from individual to collective hunting. We found that female vampire bats departed their roost individually, but often re-united far outside the roost. Nonrandomly repeating foraging encounters were predicted by within-roost association and histories of cooperation in captivity, even when controlling for kinship. Foraging bats demonstrated both affiliative and competitive interactions and a previously undescribed call type. We suggest that social foraging could have implications for social evolution if ‘local’ cooperation within the roost and ‘global’ competition outside the roost enhances fitness interdependence between frequent roostmates.

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