Inclusive Fitness Research Articles

Lifetime inclusive fitness effects of cooperative polygamy in the acorn woodpecker

Although over 50y have passed since W. D. Hamilton articulated kin selection and inclusive fitness as evolutionary explanations for altruistic behavior, quantifying inclusive fitness continues to be challenging. Here, using 30y of data and two alternative methods, we outline an approach to measure lifetime inclusive fitness effects of cooperative polygamy (mate-sharing or cobreeding) in the cooperatively breeding acorn woodpecker Melanerpes formicivorus. For both sexes, the number of offspring (observed direct fitness) declined while the number of young parented by related cobreeders (observed indirect fitness effect) increased with cobreeding coalition size. Combining these two factors, the observed inclusive fitness effect of cobreeding was greater than breeding singly for males, while the pattern for females depended on whether fitness was age-weighted, as females breeding singly accrued greater fitness at younger ages than cobreeding females. Accounting for the fitness birds would have obtained by breeding singly, however, lifetime inclusive fitness effects declined with coalition size for males, but were greater for females breeding as duos compared to breeding singly, due largely to indirect fitness effects of kin. Our analyses provide a road map for, and demonstrate the importance of, quantifying indirect fitness as a powerful evolutionary force contributing to the costs and benefits of social behaviors.

Differential grandparental investment when maternal grandmothers are living versus deceased.

Grandparents can increase their inclusive fitness by investing time and resources in their grandchildren. However, not all grandparents make such investments equally, and between-grandparent differences in this regard can be predicted based on paternity uncertainty, lineage and grandparents' sex. Using population-based data for English and Welsh adolescents (n = 1430), we examined whether the death of the most important grandparent (in terms of investment), the maternal grandmother (MGM), changes relative support for existing hypotheses predicting differential grandparental-investment patterns. To contrast the predictions of the grandparental investment hypotheses, we used generalized order-restricted information criterion approximation. We consequently found that, when MGMs are alive, the most-supported hypothesis is 'discriminative grandparental solicitude', which ranks grandparental investment as MGMs > maternal grandfathers (MGFs) > paternal grandmothers (PGMs) > paternal grandfathers (PGFs). However, when MGMs are deceased, the paternity uncertainty hypothesis (MGFs = PGMs > PGFs) receives the most support; this is due to increased investment by PGMs. Thus, when the heaviest investors (i.e. MGMs) are deceased, PGM investments are closer to-but do not exceed-MGF investments.

Early-life sibling conflict in Canada jays has lifetime fitness consequences.

While delaying natal dispersal can provide short-term benefits for juveniles, lifetime fitness consequences are rarely assessed. Furthermore, competition for limited positions on a natal territory could impose an indirect fitness cost on the winner if the outcome has negative effects on its siblings. We use radio-tracking and 58 years of nesting data in Ontario, Canada to examine the lifetime fitness consequences of sibling expulsion in the Canada jay (Perisoreus canadensis). Six weeks after fledging, intra-brood dominance struggles result in one 'dominant juvenile' (DJ) remaining on the natal territory after expelling its subordinate siblings, the 'ejectees' (EJs). Despite an older age-at-first-reproduction, DJs produced more recruits over their lifetime and had higher first-year survival than EJs, leading to substantially higher direct fitness. Even though DJs incurred an indirect fitness cost by expelling their siblings and there was no evidence that their presence on the natal territory increased their parents' reproductive output the following year, they still had substantially higher inclusive fitness than EJs. Our results demonstrate how early-life sibling conflict can have lifetime consequences and that such fitness differences in Canada jays are driven by the enhanced first-year survival of DJs pursuant to the early-summer expulsion of their sibling competitors.

The role of the ecological scaffold in the origin and maintenance of whole-group trait altruism in microbial populations

BackgroundKin and multilevel selection provide explanations for the existence of altruism based on traits or processes that enhance the inclusive fitness of an altruist individual. Kin selection is often based on individual-level traits, such as the ability to recognize other altruists, whereas multilevel selection requires a metapopulation structure and dispersal process. These theories are unified by the general principle that altruism can be fixed by positive selection provided the benefit of altruism is preferentially conferred to other altruists. Here we take a different explanatory approach based on the recently proposed concept of an “ecological scaffold”. We demonstrate that ecological conditions consisting of a patchy nutrient supply that generates a metapopulation structure, episodic mixing of groups, and severe nutrient limitation, can support or “scaffold” the evolution of altruism in a population of microbes by amplifying drift. This contrasts with recent papers in which the ecological scaffold was shown to support selective processes and demonstrates the power of scaffolding even in the absence of selection.ResultsUsing computer simulations motivated by a simple theoretical model, we show that, although an altruistic mutant can be fixed within a single population of non-altruists by drift when nutrients are severely limited, the resulting altruistic population remains vulnerable to non-altruistic mutants. We then show how the imposition of the “ecological scaffold” onto a population of non-altruists alters the balance between selection and drift in a way that supports the fixation and subsequent persistence of altruism despite the possibility of invasion by non-altruists.ConclusionsThe fixation of an altruistic mutant by drift is possible when supported by ecological conditions that impose a metapopulation structure, episodic mixing of groups, and severe nutrient limitation. This is significant because it offers an alternative explanation for the evolution of altruism based on drift rather than selection. Given the ubiquity of low-nutrient “oligotrophic” environments in which microbes exist (e.g., the open ocean, deep subsurface soils, or under the polar ice caps) our results suggest that altruistic and cooperative behaviors may be highly prevalent among microbial populations.

No Signs of Inclusive Fitness or Reciprocal Altruism in Advantageous Inequity Aversion.

Advantageous inequity aversion (i.e., the tendency to respond negatively to unfairness that benefits oneself) usually develops in 6-8-year-olds. However, little is known about the selection pressures that might have shaped this phenomenon. Using data collected from 120 4-8-year-old Finnish children, we tested two evolutionary explanations for the development of advantageous inequity aversion: reciprocal altruism (i.e., benefiting from sharing when the roles are likely reversed in the future) and inclusive fitness (i.e., benefiting from sharing with biological relatives that carry the same alleles). We first successfully replicated a previous experiment, showing that 6-8-year-olds display advantageous inequity aversion by preferring to throw away a resource rather than keep it for themselves. Here, this behavior was also displayed in 5-year-olds. Using a novel experiment, we then asked children to distribute five erasers between themselves, a sibling, a peer, and a stranger. That is, an equal distribution was only possible if throwing away one eraser. We found no support for advantageous inequity aversion being shaped by either inclusive fitness or reciprocal altruism. Future studies could investigate costly signaling and adherence to social norms to avoid negative consequences as ultimate explanations for advantageous inequity aversion.

How prenatal cortisol levels relate to grandmother-mother relationships among a cohort of Latina women.

As part of the human reproductive strategy, mothers receive childcare assistance from others. For kin, allomothers are adaptively incentivized to provide assistance due to inclusive fitness benefits. Previous studies across a broad range of populations identify grandmothers as particularly consistent allomothers. Minimal attention has been paid to the possibility that allomothers may begin investing in offspring quality during the prenatal stage of life. Here, we innovate within the area of grandmother allocare research by examining the prenatal stage of life and biopsychosocial mechanisms by which prenatal grandmother effects may be enacted. Data derive from the Mothers' Cultural Experiences study, a cohort of 107 pregnant Latina women in Southern California. At <16 weeks' gestation, we administered questionnaires, collected morning urine samples, and measured cortisol by enzyme-linked immunosorbent assay, correcting for specific gravity. We measured the soon-to-be maternal and paternal grandmothers' relationship quality, social support, frequency of seeing each other, communicating, and geographic proximity to pregnant mothers, that is, their daughters and daughters-in-law. These measures were self-reported by the pregnant mothers. We assessed how grandmother constructs related to the pregnant women's depression, stress, anxiety, and cortisol levels. We observed benefits conferred by maternal grandmothers for mothers' prenatal mental health and lower cortisol levels. Paternal grandmothers also conferred mental health benefits to pregnant daughters-in-law, but higher cortisol levels. Our results suggest that grandmothers, especially maternal grandmothers, are able to improve their inclusive fitness by caring for pregnant daughters, and allomother support may positively impact prenatal health. This work extends the traditional cooperative breeding model by identifying a prenatal grandmother effect, and, by examining a maternal biomarker.

Creating the First Professional Doctor of Clinical Exercise Physiology Program and a Call to Expand the Model

The inaugural cohort of the professional Doctor of Clinical Exercise Physiology (DCEP) program started its training during the Fall 2022 semester at the University of Illinois at Chicago (UIC). This first-of-its-kind program in CEP provides unique didactic and applied training opportunities beyond what is currently available at the masters level. Our model is an accelerated 1-year extension to masters level training in CEP and aims to: (a) prepare students to effectively work with clinically complex patients, (b) build leadership skills to manage clinical personnel, and (c) prepare students to understand the foundations of creating and maintaining financially sound clinical programs (1–3).In conceptualizing the DCEP program's offerings, an internal review (not published) of CEP masters graduate programs across the nation was conducted to understand areas of training that received great attention and areas feasibly within the CEP's professional prevue that received little attention. As anticipated, many programs placed a heavy emphasis on delivering didactic and practical training to prepare students to work with individuals with cardiovascular diseases, which correlates well with the high percentage of CEPs who report working in cardiac rehabilitation (4). Moreover, programs emphasized preparing students for the American College of Sports Medicine Certified Clinical Exercise Physiologist (ACSM-CEP) exam with little or no focus on other specialty certifications available through the ACSM (i.e., Certified Cancer Exercise Trainer, Certified Inclusive Fitness Trainer). Accordingly, we have developed advanced courses on the assessment and delivery of exercise in individuals with musculoskeletal conditions, spinal cord lesions, neuromuscular conditions, cognitive disabilities, various cancers, and chronic kidney disease. In addition to ACSM's certifications and certificates, another professionally meaningful and rewarding certification that many programs do not prepare their students for is the Certified Diabetes Care and Education Specialist (CDCES) through the Association of Diabetes Care and Education Specialists. The DCEP program thus offers a course, clinical observations with CDCES professionals, and opportunities to directly deliver diabetes education in order to give students the necessary information and hours to sit for the exam. Lastly, we have included our department's existing cardiovascular imaging courses to teach students the knowledge and skills to perform and analyze cardiac echocardiograms as well as other vascular images. This presents another opportunity for the DCEP student to expand their toolkit and increase their marketability when applying for clinical or academic/research positions that have cardiovascular imaging as a part of their department or research studies.In our review of programs, another common observation was the incorporation of a course that reviews the professional responsibilities of an employee working in a cardiac rehabilitation and/or pulmonary rehabilitation setting. However, it did not appear that programs offered high level training that builds strong foundations in leadership, personnel and business management, marketing, or clinical program development that ensures financial stability. Many of these professional skills are instead acquired on the job over the course of a career. For this reason, UIC's professional DCEP program offers professional development courses that prepare students to be effective leaders and future program managers earlier in their careers.To continue to hone and grow our DCEP program, an additional goal is to increase the number of DCEP programs nationally and internationally. The University of Mary in Bismarck, North Dakota, is currently in the process of completing and submitting their proposal to their institution to launch a DCEP program along with other institutions beginning conversations within their departments. Departments interested in developing a DCEP option can follow a similar model that allows students to decide whether or not they want to continue after completing their masters degree. Key aspects of UIC'S DCEP program that fosters applied training opportunities is the existence of a Faculty Practice where faculty deliver services to high risk and clinically diverse patients as well as agreements with hospitals that gives our students access to multidisciplinary practitioners and unique clinical cases. Lastly, it is important to acknowledge that a DCEP degree is not mandatory nor anticipated to be the entry level degree to be an effective or competent CEP. Our students' primary motivating factor for pursuing a DCEP degree is to grow their clinical knowledge and skills in ways that are not currently available through the traditional PhD model. From our current observations, we have seen students quickly expand their ability to confidently work with patients with clinically complex conditions, deliver diabetes care and education, as well as understand and apply the fundamentals of leadership. These collective experiences have provided reassurance that the DCEP model will indeed elevate the CEPs and ultimately the field.

From learning ‘who monkeys support’, we infer ‘What they know’

Though understanding what monkeys see and know without inferring anthropomorphically is virtually impossible, the more detail and concrete the ground of this inference we have, the more promising our surmise would be. A closer look into the male-male relation in cercopithecines, a genus of old world monkeys, confirms what scientists have theorized: in the absence of inclusive fitness advantage, the males cooperate closely with nonkins following the norm of reciprocity, resulting in a stratified rather than linear, continuous dominance hierarchy, as a function of seniority and age. This feature is ubiquitous and found in 3 species of macaques and yellow baboons; and it is reliably robust across 4 continents, 5 study sites, 17 troops, and 297 monkeys. In other words, although new members of a group are often at the prime age of belligerence, because senior males share a longer history of cohabitation and reciprocal relation with one another, they intervene in each other’s fight and outcompete the new members who are often not supported. This implies that, in cercopithecines, the support to nonkins may be guided by a mental scorebook, which enforces them to reciprocate in the future when their reciprocal partners are in need.

Intra-colony venom diversity contributes to maintaining eusociality in a cooperatively breeding ant

BackgroundEusociality is widely considered to evolve through kin selection, where the reproductive success of an individual’s close relative is favored at the expense of its own. High genetic relatedness is thus considered a prerequisite for eusociality. While ants are textbook examples of eusocial animals, not all ants form colonies of closely related individuals. One such example is the ectatommine ant Rhytidoponera metallica, which predominantly forms queen-less colonies that have such a low intra-colony relatedness that they have been proposed to represent a transient, unstable form of eusociality. However, R. metallica is among the most abundant and widespread ants on the Australian continent. This apparent contradiction provides an example of how inclusive fitness may not by itself explain the maintenance of eusociality and raises the question of what other selective advantages maintain the eusocial lifestyle of this species.ResultsWe provide a comprehensive portrait of the venom of R. metallica and show that the colony-wide venom consists of an exceptionally high diversity of functionally distinct toxins for an ant. These toxins have evolved under strong positive selection, which is normally expected to reduce genetic variance. Yet, R. metallica exhibits remarkable intra-colony variation, with workers sharing only a relatively small proportion of toxins in their venoms. This variation is not due to the presence of chemical castes, but has a genetic foundation that is at least in part explained by toxin allelic diversity.ConclusionsTaken together, our results suggest that the toxin diversity contained in R. metallica colonies may be maintained by a form of group selection that selects for colonies that can exploit more resources and defend against a wider range of predators. We propose that increased intra-colony genetic variance resulting from low kinship may itself provide a selective advantage in the form of an expanded pharmacological venom repertoire. These findings provide an example of how group selection on adaptive phenotypes may contribute to maintaining eusociality where a prerequisite for kin selection is diminished.

Negative but antagonistic effects of neonicotinoid insecticides and ectoparasitic mites Varroa destructor on Apis mellifera honey bee food glands

Collaborative brood care by workers is essential for the functionality of eusocial Apis mellifera honey bee colonies. The hypopharyngeal food glands of workers play a crucial role in this context. Even though there is consensus that ubiquitous ectoparasitic mites Varroa destructor and widespread insecticides, such as neonicotinoids, are major stressors for honey bee health, their impact alone and in combination on the feeding glands of workers is poorly understood. Here, we show that combined exposure to V. destructor and neonicotinoids antagonistically interacted on hypopharyngeal gland size, yet they did not interact on emergence body mass or survival. While the observed effects of the antagonistic interaction were less negative than expected based on the sum of the individual effects, hypopharyngeal gland size was still significantly reduced. Alone, V. destructor parasitism negatively affected emergence body mass, survival, and hypopharyngeal gland size, whereas neonicotinoid exposure reduced hypopharyngeal gland size only. Since size is associated with hypopharyngeal gland functionality, a reduction could result in inadequate brood care. As cooperative brood care is a cornerstone of eusociality, smaller glands could have adverse down-stream effects on inclusive fitness of honey bee colonies. Therefore, our findings highlight the need to further study how ubiquitous stressors like V. destructor and neonicotinoids interact to affect honey bees.

Adolescence Predatory Risk Alters Social Behaviors and Cognitive Ability and Central Oxytocin and Vasopressin Expression in Adult Brandt’s Voles

Introduction: Stress during adolescence causes long-term behavioral changes in adulthood. We previously found that adolescent exposure to predatory risk augments adolescent social contact and adult parental behavior in Brandt’s voles (Lasiopodomys brandtii). Methods: Here, we determined whether this experience alters sexual behavior, pair-bond formation, and recognition ability as well as basal HPA axis activity, central oxytocin (OT), and arginine-vasopressin (AVP) expression in adulthood. Results: In the social interaction test, repeated cat odor (CO) exposure enhanced the frequency of lordosis by female voles toward an unfamiliar opposite-sex conspecific. CO voles preferred to engage with their partners after 48-h cohabitation whereas the control groups did not, which may reflect stable pair bonds in the CO treatment group. Furthermore, adolescent exposure to CO inhibited novel object recognition and place recognition ability, while it influenced social recognition only among adult males. No effect of adolescent CO exposure was observed for basal HPA axis activity, showing a habituation effect. Finally, we found that CO exposure increased OT and decreased AVP expression in the hypothalamus, including the paraventricular nucleus and anterior hypothalamus. The levels of OT in the medial amygdala were lower, and AVP in the lateral septum was higher in CO voles compared with the control. Conclusion: These findings demonstrate that adolescent exposure to predator risk promotes adult reproductive behavior of Brandt’s voles. Deficits in recognition ability may necessitate alterations in reproductive strategies to enhance inclusive fitness. OT and AVP systems may play a modulatory role in the alteration of social behaviors elicited by adolescent predatory risk.

Re-thinking water use in pig diets while accounting for food-feed competition

Livestock feed production is one of the primary users of freshwater and arable land, and it is also in competition with human food production. Therefore, we require reconsideration of the way we use freshwater in livestock feed production. The objective of this study is to assess the impact on freshwater use of pork production by using alternative pig diets based on local feed ingredients, or by-products. We used a lifecycle approach to analyse the freshwater use associated with feed production to produce one kg of pork. We explored three feeding scenarios (STANDARD: diets commercially used in Ireland; LOCAL: diets based on ingredients grown in Ireland; and BY-PRODUCT: diets based on by-products only). We calculated the freshwater use, using the water footprint (WFP) method, and the competition for water use between food and feed production using the water use ratio (WUR) for each scenario. The WUR quantifies the maximum amount of human digestible protein (HDP) derived from food crops that could be produced on the same land, and using the same water resources, that were used to grow the feed ingredients needed to produce 1 kg of pork.The WFP of the scenarios was 2,470 L/kg pork for STANDARD, 2,492 L/kg pork for LOCAL, and 2,205 L/kg pork for BY-PRODUCT. When we considered the WUR, none of the scenarios had a value < 1 (i.e. in all scenarios, more HDP can be produced from direct cultivation of food crops rather than pork). However, the BY-PRODUCT scenario (1.4) performed better than STANDARD (1.9) and LOCAL (2.9). Beet pulp and bakery by-products had zero WFP and no edibility and were thus considered promising ingredients. Moreover, rapeseed meal had a low WFP and rapeseed meal and sunflower seed meal are not considered human edible and were considered fit for future inclusion in diets. We also concluded that both the WFP and WUR methods have separate strengths and limitations, and should thus be used in conjunction; the ideal diet is one with the minimum WFP and WUR. Consideration of human edibility of feed ingredients is an important approach which should be included in future studies. Moreover, the entire food system including dairy, beef, poultry and other competitive uses should be taken into account when considering which feed ingredients to use in pig diets.

Does higher perceived risk of morbidity and mortality decrease risk-taking?

Previous studies have shown that people change their behaviour in response to negative shocks such as economic downturns or natural catastrophes. Indeed, the optimal behaviour in terms of inclusive fitness often varies according to a number of parameters, such as the level of mortality risk in the environment. Beyond unprecedented restrictions in everyday life, the COVID-19 pandemic has profoundly affected people's environment. In this study, we investigated how people form their perception of morbidity and mortality risk associated with COVID-19 and how this perception in turn affects psychological traits, such as risk-taking and patience. We analysed data from a large survey conducted during the first wave in France on 3353 nationally representative people. We found that people use public information on COVID-19 deaths in the area where they live to form their perceived morbidity and mortality risk. Using a structural model approach to lift endogeneity concerns, we found that higher perceived morbidity and mortality risk increases risk aversion. We also found that higher perceived morbidity and mortality risk leads to less patience, although this was only observed for high levels of perceived risk. Our results suggest that people adapt their behaviour to anticipated negative health shocks, namely the risk of becoming sick or dying of COVID-19.

Research status and development trend of altruism in the biological field - knowledge graph analysis based on CiteSpace

Based on the visualization analysis of foreign literature on altruistic behavior in recent ten years (2012-2022) by CiteSpace, it is found that the research on altruistic behavior in the field of biology abroad has experienced the initial exploratory stage, the outbreak stage, and now enters the stable and deepening stage. The discipline distribution is mainly behavioral ecology, supplemented by evolutionary biology, biomathematics, and genetics. The author has three main cooperative groups, and a relatively tight cooperative network has been formed locally in related fields. From the perspective of cooperation degree, the cooperation density of major research institutions is high, and relevant research has been relatively mature. Judging from the period calculated in the software, altruism, cooperation, kin Selection, reciprocity, and inclusive fitness emerged earlier. In recent years, constitutive theory, density dependence, and Habitat construction have emerged, which may become a new direction for future research. Therefore, future research can expand the scope of disciplines, strengthen the cooperation between authors and units, and explore other research hotspots.

Is Aging an Inevitable Characteristic of Organic Life or an Evolutionary Adaptation?

Aging is an evolutionary paradox. Several hypotheses have been proposed to explain it, but none fully explains all the biochemical and ecologic data accumulated over decades of research. We suggest that senescence is a primitive immune strategy which acts to protect an individual's kin from chronic infections. Older organisms are exposed to pathogens for a longer period of time and have a higher likelihood of acquiring infectious diseases. Accordingly, the parasitic load in aged individuals is higher than in younger ones. Given that the probability of pathogen transmission is higher within the kin, the inclusive fitness cost of infection might exceed the benefit of living longer. In this case, programmed lifespan termination might be an evolutionarily stable strategy. Here, we discuss the classical evolutionary hypotheses of aging and compare them with the pathogen control hypothesis, discuss the consistency of these hypotheses with existing empirical data, and present a revised conceptual framework to understand the evolution of aging.

Kin discrimination in cannibalism by a predatory mite, Amblyseius herbicolus (Chant) (Acari: Phytoseiidae)

Kin recognition has been widely observed across the animal kingdom. Individuals discriminate and treat conspecifics differently in relation to their genetic relatedness to increase their inclusive fitness (i.e. their own reproductive success and that of their relatives) and to avoid adverse influences from inbreeding. Although most studies on kin recognition have focused on group-living species, this behaviour can also be adaptive in solitary species.

Parental Negativity Toward Offspring’s Minority Sexual Orientation Disclosures: An Inclusive Fitness Perspective

Adolescents and young adults who disclose a minority sexual orientation (“come out” as gay, lesbian, or bisexual) to their parents often are met with varied negative reactions. The current work builds on a growing literature aimed at understanding the myriad causes of negative parental reactions to these disclosures. Specifically, this work evaluates a hypothesis derived from evolutionary psychological logic: that variation in parental responses to offspring’s sexual orientation disclosures is driven, in part, by perceived costs to parents’ inclusive fitness (i.e., implicit or explicit concerns related to the reproductive success of genetic relatives). Across three studies (total N = 493), we examined whether daughters’ and sons’ perceptions of parents’ negative reactions to their sexual orientation disclosures systematically co-varied with inclusive fitness concerns, as indexed by parent gender, sexual orientation, and offspring number. This perspective received partial support among daughters, who reported more negative reactions from their mothers (vs. fathers), particularly in response to lesbian (vs. bisexual) disclosures. Reactions to sons’ disclosures did not vary across parent gender, sexual orientation, or offspring number. Taken together, this work provides preliminary evidence that perceived fitness costs may lead mothers to respond negatively to their daughters’ lesbian orientation disclosures.

Social network analysis reveals context-dependent kin relationships in wild sulphur-crested cockatoos Cacatua galerita.

A preference to associate with kin facilitates inclusive fitness benefits, and increased tolerance or cooperation between kin may be an added benefit of group living. Many species exhibit preferred associations with kin; however, it is often hard to disentangle active preferences from passive overlap, for example caused by limited dispersal or inheritance of social position. Many parrots exhibit social systems consisting of pair-bonded individuals foraging in variably sized fission-fusion flocks within larger communal roosts of hundreds of individuals. Previous work has shown that, despite these fission-fusion dynamics, individuals can exhibit long-term preferred foraging associations outside their pair bonds. Yet the underlying drivers of these social preferences remain largely unknown. In this study, we use a network approach to examine the influence of kinship on social associations and interactions in wild, communally roosting sulphur-crested cockatoos, Cacatua galerita. We recorded roost co-membership, social associations and interactions in 561 individually marked birds across three neighbouring roosts. We then collected genetic samples from 205 cockatoos, and conducted a relationship analysis to construct a kinship network. Finally, we tested correlations between kinship and four social networks: association, affiliative, low-intensity aggression and high-intensity aggression. Our result showed that while roosting groups were clearly defined, they showed little genetic differentiation or kin structuring. Between roost movement was high, with juveniles, especially females, repeatedly moving between roosts. Both within roosting communities, and when visiting different roosts, individuals preferentially associated with kin. Supporting this, individuals were also more likely to allopreen kin. However, contrary to expectation, individuals preferred to direct aggression towards kin, with this effect only observed when individuals shared roost membership. By measuring social networks within and between large roosting groups, we could remove potential effects of passive spatial overlap on kin structuring. Our study reveals that sulphur-crested cockatoos actively prefer to associate with kin, both within and between roosting groups. By examining this across different interaction types, we further demonstrate that sulphur-crested cockatoos exhibit behavioural and context-dependent interaction rules towards kin. Our results help reveal the drivers of social association in this species, while adding to the evidence for social complexity in parrots.

Understanding the Reasons Why Men and Women Do Not Donate Gametes

The global under-supply of sperm and oocyte donors is a serious concern for assisted reproductive medicine. Research has explored self-selected populations of gamete donors and their ex-post rationalisations of why they chose to donate. However, such studies may not provide the necessary insight into why the majority of people do not donate. Utilising the unique open form responses of a large sample (n = 1035) of online survey respondents, we examine the reasons participants cite when asked: “Why haven’t you donated your sperm/eggs?.” We categorise these responses into four core themes (conditional willingness, barriers, unconsidered, and conscientious objector) and eleven lower-order themes. We find that, on average, women are more conditionally willing (8.2% difference; p = 0.008) to participate in gamete donation than men. We also find that women are more likely than men to justify their non-donation based on their reproductive history (21.3% difference; p = 0.000) or kin selection and inclusive fitness (5.7% difference; p = 0.008). However, compared to women, men are more likely to validate their non-donation based on sociocultural or social norms (6% difference; p = 0.000) or religion (1.7% difference; p = 0.030). That so many of our study participants report in-principal willingness for future participation in gamete donation speaks to the need for increased research on understanding non-donor population preferences, motivations, and behaviours.

Domestic pigs (Sus scrofa) engage in non-random post-conflict affiliation with third parties: cognitive and functional implications

In social mammals, conflict resolution involves the reunion of former opponents (aggressor and victim) after an aggressive event (reconciliation) or post-conflict triadic contacts with a third party, started by either opponent (solicited-TSC) or spontaneously offered by the third party (unsolicited-TUC). These post-conflict strategies can serve different functions, including consolation (specifically when TUCs reduce the victim’s anxiety). We investigated the possible presence and modulating factors of such strategies on semi-free ranging pigs (Sus scrofa; N = 104), housed at the ethical farm Parva Domus (Cavagnolo, Italy). Kinship was known. Reconciliation was present and mainly occurred between weakly related pigs to possibly improve tolerant cohabitation. Triadic contacts (all present except aggressor TSCs) mostly occurred between close kin. TSCs enacted by victims reduced neither their post-conflict anxiety behaviors nor further attacks by the previous aggressor, possibly because TSCs remained largely unreciprocated. TUCs towards aggressors did not reduce aggressor post-conflict anxiety but limited aggression redirection towards third parties. TUCs towards the victim reduced the victim but not the third-party’s anxiety. However, TUCs may also provide inclusive fitness benefits to third parties by benefiting close kin. In sum, pigs engaged in non-random solicited/unsolicited triadic contacts, which suggests that pigs might possess socio-emotional regulation abilities to change their own or others’ experience and elements of social appraisal, necessary to detect the emotional arousal of relevant others and (in case of TUCs) take the agency to restore homeostasis.