Absence of kin discrimination in a ponerine ant

Kinship theory implies that individual social Hymenoptera should be able to identify kin. We tested kin discrimination in the polygynous ponerine ant Gnamptogenys striatula. Mate choice experiments showed that individuals did not pair according to kinship. Experiments on matriline discrimination revealed that workers did not preferentially groom, transport (after nest disturbance) or cannibalize (after starvation) larvae on the basis of kin, when both related and unrelated larvae were present. These results show the absence of kin discrimination for the criteria and experimental conditions used. The lack of kin discrimination during mate choice in G. striatula can be explained by male dispersion and female philopatry, which reduces the likelihood of mating between siblings and of kin-based mate choice reflected in incest avoidance. The lack of matriline discrimination by workers may reflect permanent intracolony mutualism or the high cost of discrimination. Finally, it appears that the absence of kin discrimination in such contexts in G. striatula is not incompatible with kinship theory and may have been secondarily selected during social evolution. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Caring across Boundaries versus Keeping Boundaries Intact: Links between Moral Values and Interpersonal Orientations

Prior work has established robust diversity in the extent to which different moral values are endorsed. Some people focus on values related to caring and fairness, whereas others assign additional moral weight to ingroup loyalty, respect for authority and established hierarchies, and purity concerns. Five studies explore associations between endorsement of distinct moral values and a suite of interpersonal orientations: Machiavellianism, prosocial resource distribution, Social Dominance Orientation, and reported likelihood of helping and not helping kin and close friends versus acquaintances and neighbors. We found that Machiavellianism (Studies 1, 3, 4, 5) (e.g., amorality, controlling and status-seeking behaviors) and Social Dominance Orientation (Study 4) were negatively associated with caring values, and positively associated with valuation of authority. Those higher in caring values were more likely to choose prosocial resource distributions (Studies 2, 3, 4) and to report reduced likelihood of failing to help kin/close friends or acquaintances (Study 4). Finally, greater likelihood of helping acquaintances was positively associated with all moral values tested except authority values (Study 4). The current work offers a novel approach to characterizing moral values and reveals a striking divergence between two kinds of moral values in particular: caring values and authority values. Caring values were positively linked with prosociality and negatively associated with Machiavellianism, whereas authority values were positively associated with Machiavellianism and Social Dominance Orientation.     

OF MICE AND KIN: THE FUNCTIONAL SIGNIFICANCE OF KIN BIAS IN SOCIAL BEHAVIOUR

1. Sharing recent ancestry (kinship) increases the degree of genetic similarity between individuals, where genetic similarity could mean anything from sharing a particular allele to sharing an entire genome. 2. Genetic similarity can influence behavioural and other responses between individuals in a number of ways, discriminatory and non-discriminatory. All are likely to result in kin bias, because of the correlation between genetic similarity and kinship, but only some should be regarded as involving kin discrimination. 3. Non-discriminatory kin bias could arise through close relatives sharing, for instance, physical characteristics (such as those influencing competitive ability), thresholds of behavioural response or requirements for particular resources. 4. Discriminatory kin bias could arise through the direct perception of genetic similarity between individuals (direct similarity discrimination) or the use of cues likely to correlate with genetic similarity (indirect similarity discrimination--of which kin discrimination is one form). Alternatively, it could arise incidentally through mistaken identity or discrimination at some other level, such as species identification. 5. Experiments with laboratory and wild house mice have revealed kin bias in a number of contexts, including (a) parental and infanticidal behaviour, (b) sexual development and behaviour and (c) investigatory behaviour and passive body contact among juveniles and adults. 6. While kin bias in mice has been interpreted as evidence for kin discrimination, there are several problems with such an interpretation. These include (a) pronounced and complex effects of familiarity on discrimination, (b) a high risk of error-proneness in the indirect cues used in apparent kin discrimination and (c) weak and easily disrupted kin bias effects in certain contexts. 7. Consideration of social structure and discriminatory responses within populations of wild house mice leads to an alternative explanation for some kin bias in terms of incidental discrimination based on social group membership. 8. Several results from laboratory experiments suggest incidental discrimination is a more parsimonious explanation than kin discrimination for some intrasexual kin bias in behaviour. However, kin or direct similarity discrimination appears to be the most likely explanation for other aspects of intrasexual kin bias and for intersexual kin bias.     

Genetic relatedness in wintering groups of house sparrows (Passer domesticus)

Social behaviour of group-living animals is often influenced by the relatedness of individuals, thus understanding the genetic structure of groups is important for the interpretation of costs and benefits of social interactions. In this study, we investigated genetic relatedness in feeding aggregations of free-living house sparrows ( Passer domesticus ) during the nonbreeding season. This species is a frequent model system for studies of social behaviour (e.g. aggression, social foraging), but we lack adequate information on the kin structure of sparrow flocks. During two winters, we ringed and observed sparrows at feeding stations, and used resightings to identify stable flock-members and to calculate association indices between birds. We genotyped the birds using seven highly polymorphic microsatellite loci, and estimated pairwise relatedness coefficients and relatedness categories (close kin vs. unrelated) by maximum likelihood method. We found that most birds were unrelated to each other in the flocks (mean ± SE relatedness coefficient: 0.06 ± 0.002), although most individuals had at least a few close relatives in their home flock (14.3 ± 0.6% of flock-mates). Pairwise association between individuals was not significantly related to their genetic relatedness. Furthermore, there was no difference between within-flock vs. between-flock relatedness, and birds had similar proportions of close kin within and outside their home flock. Finally, relatedness among members of different flocks was unrelated to the distance between their flocks. Thus, sparrow flocks were not characterized by association of relatives, nevertheless the presence of some close kin may provide opportunity for kin-biased behaviours to evolve.     

Kin influences on fertility in Thailand: Effects and mechanisms

It has been suggested that human mothers are cooperative breeders, as they need help from others to successfully raise offspring. Studies working under this framework have found correlations between the presence of kin and both child survival and female fertility rates. This study seeks to understand the proximate mechanisms by which kin influence fertility using data from the 1987 Thailand Demographic and Health Survey (DHS), a nationally representative sample of 6775 women. Kin influence is measured by the length of time couples live with the husband's or wife's parents after marriage. Event history analysis, multilevel modeling and structural equation modeling are used to investigate both fertility outcomes and potential pathways through which postnuptial residence may influence fertility outcomes, including employment status, maternal and child outcomes, contraceptive use, breastfeeding duration, and age at marriage. We show that living virilocally (with husband's kin after marriage) increases total fertility by shortening time from marriage to first birth, and increasing the likelihood of progression to each subsequent birth. These effects are mediated through correlations between virilocal residence and earlier age at marriage as well as delayed initiation of contraceptive use. We find no influence of husband's kin on maternal or child outcomes. Living uxorilocally (with wife's kin after marriage) also reduces age at marriage, shortens time from marriage to first birth and (marginally) improves child survivorship, but has no effect on other child and maternal outcomes or progression to subsequent births and results in a similar number of living children as women living neolocally.     

Cannibalistic siblicide in praying mantis nymphs (Miomantis caffra)

Inclusive fitness theory predicts that cannibalism should be more likely to arise if close relatives can be avoided, suggesting that cannibalistic species will possess mechanisms for minimizing predation on kin. Juvenile Miomantis caffra are good candidates for the possession of such traits because; (1) groups of siblings hatch together into the same locale, (2) they are aggressive hunters, and (3) they are strongly cannibalistic. In this study, the possibility of kin recognition or avoidance in M. caffra is investigated by laboratory comparison of cannibalism rates between groups of differing relatedness. In order to examine the likelihood of encounters between early instar siblings, the extent of dispersal away from the ootheca in the days following hatching is also observed. Nymphs did not rapidly disperse after hatching, so the chances of full siblings encountering one another in the wild appear to be high. Despite this, cannibalism was equally high in groups of full siblings and groups of mixed parenthood. We suggest that for M. caffra, a generalist ambush predator, the benefits of indiscriminate aggression may outweigh any inclusive fitness benefits that would be gained from kin discrimination.     

Participation of kin17 protein in replication factories and in other DNA transactions mediated by high molecular weight nuclear complexes

The Homo sapiens kin17 ((HSA)kin17) protein is a chromatin-associated protein conserved during evolution and overproduced in certain human tumor cell lines. For the first time, immunoelectron microscopy analysis of endogenous (HSA)kin17 protein revealed an ultrastructural co-localization of (HSA)kin17 and bromodeoxyuridine (BrdUrd) at sites of DNA replication after either short (15 min) or long (120 min) pulses of BrdUrd labeling. After hydroxyurea (HU) or L-mimosine (Mimo) block and withdrawal, we observed that (HSA)kin17 was recruited onto the chromatin during the re-entry and the progression in the S phase. These results are consistent with a major role of (HSA)kin17 protein in DNA replication factories. Other treatments hampering replication fork progression and/or inducing double-strand breaks also triggered an accumulation and a concentration of the chromatin-bound (HSA)kin17 protein into large intranuclear foci 24 h post-treatment. Moreover, HU- and Mimo-induced (HSA)kin17 foci were retained in the nucleus after detergent extraction, suggesting a strong association with nuclear structures. Gel filtration analyses of cellular extracts showed that endogenous (HSA)kin17 protein co-eluted with both replication proteins RPA32 and RPA70 in a fraction containing complexes of M(r) 600,000. Interestingly, HU-induced G(1)-S arrest triggered an increase in the molecular weight of complexes containing (HSA)kin17 protein. Hence, treatments interfering with either initiation and/or elongation of DNA replication also recruited chromatin-bound (HSA)kin17 protein. We hypothesize that in the presence of unrepaired DNA damage, (HSA)kin17 protein concentrated into high molecular weight complexes probably to create a bridge that contributes to the harmonization of DNA replication and repair.     

Kin Selection in Primate Groups

Altruism poses a problem for evolutionary biologists because natural selection is not expected to favor behaviors that are beneficial to recipients, but costly to actors. The theory of kin selection, first articulated by Hamilton (1964), provides a solution to the problem. Hamilton's well-known rule (br > c) provides a simple algorithm for the evolution of altruism via kin selection. Because kin recognition is a crucial requirement of kin selection, it is important to know whether and how primates can recognize their relatives. While conventional wisdom has been that primates can recognize maternal kin, but not paternal kin, this view is being challenged by new findings. The ability to recognize kin implies that kin selection may shape altruistic behavior in primate groups. I focus on two cases in which kin selection is tightly woven into the fabric of social life. For female baboons, macaques, and vervets maternal kinship is an important axis of social networks, coalitionary activity, and dominance relationships. Detailed studies of the patterning of altruistic interactions within these species illustrate the extent and limits of nepotism in their social lives. Carefully integrated analyses of behavior, demography, and genetics among red howlers provide an independent example of how kin selection shapes social organization and behavior. In red howlers, kin bonds shape the life histories and reproductive performance of both males and female. The two cases demonstrate that kin selection can be a powerful source of altruistic activity within primate groups. However, to fully assess the role of kin selection in primate groups, we need more information about the effects of kinship on the patterning of behavior across the Primates and accurate information about paternal kin relationships.     

A test of alternative hypotheses for kin recognition in cannibalistic tiger salamanders

The function of kin recognition is controversial. We investigatedthe adaptive significance of kin discrimination in cannibalistictiger salamander larvae, Ambystoma tigrinum. Previous laboratoryexperiments show that cannibals preferentially consume lessrelated individuals. We hypothesized that this example of kinrecognition (1) is a laboratory artifact, (2) is a by-productof sibship-specific variation in escape responses, because cannibalsfrom families with rapid responses may be more likely to cannibalize slowlyescaping non-kin, (3) is an epiphenomenon of species recognition,(4) functions in disease avoidance, because kin may be moreinfectious than non-kin, or (5) is favored by kin selection.We evaluated these five hypotheses by using laboratory and fieldexperiments to test specific predictions made by each hypothesis.We rejected hypotheses 1-4 above because (1) kin recognitionwas expressed in the wild, (2) escape responses did not reliablypredict whether a cannibal would ingest kin or non-kin, (3)kin recognition was not most pronounced in populations wheretiger salamanders co-occur with other species of salamanders,and (4) non-kin prey were more likely than kin to transmit pathogensto cannibals. However, we established that the necessary conditionfor kin selection, Hamilton's rule, was met. Thus, our resultsimplicate kin selection as the overriding reason that cannibalistictiger salamanders discriminate kin.     

Routes to indirect fitness in cooperatively breeding vertebrates: kin discrimination and limited dispersal

Hamilton demonstrated that the evolution of cooperative behaviour is favoured by high relatedness, which can arise through kin discrimination or limited dispersal (population viscosity). These two processes are likely to operate with limited overlap: kin discrimination is beneficial when variation in relatedness is higher, whereas limited dispersal results in less variable and higher average relatedness, reducing selection for kin discrimination. However, most empirical work on eukaryotes has focused on kin discrimination. To address this bias, we analysed how kin discrimination and limited dispersal interact to shape helping behaviour across cooperatively breeding vertebrates. We show that kin discrimination is greater in species where the: (i) average relatedness in groups is lower and more variable; (ii) effect of helpers on breeders reproductive success is greater; and (iii) probability of helping was measured, rather than the amount of help provided. There was also an interaction between these effects with the correlation between the benefits of helping and kin discrimination being stronger in species with higher variance in relatedness. Overall, our results suggest that kin discrimination provides a route to indirect benefits when relatedness is too variable within groups to favour indiscriminate cooperation.     

Does kin-biased territorial behavior increase kin-biased foraging in juvenile salmonids?

We examined the effects of kin-biased territorial defense behavioron the distribution of foraging attempts and percent weightchanges (fitness benefits) in juvenile Atlantic salmon (Salmosalar) and rainbow trout (Oncorhynchus mykiss) in an artificialstream channel. The individual percent weight changes and frequencyof aggressive interactions and foraging attempts were quantifiedin kin (full sibling) and non-kin groups of salmon and troutWe observed kin groups of both species to obtain significantlygreater mean and less variable percent weight gains that non-kingroups. In addition, faster-growing (dominant)individuals ofboth species within kin groups exhibited significantly feweraggressive interactions than did faster-growing nonkin individuals,while we observed no difference between kin and non-kin slower-growing(subordinate) individuals. Slowergrowing kin individuals ofboth species obtained significantly more foraging opportunitiesthan slower-growing non-kin individuals while there was no differencebetween faster-growing kin and non-kin individuals. These datasuggest that reduced aggression by faster-growing individualstowards slower-growing kin enables slower-growing kin to obtainmore foraging opportunities, resulting in higher and less variablepercent weight changes. These data also suggest that as a resultof kin-biased territorial defense and foraging behavior, juvenileAtlantic salmon and rainbow trout may be able to maximize inclusivefitness potential by defending territories near related conspecifics.     

Responses of young black skimmers to high-intensity distress notes

The semi-precocial young of the black skimmer (Rynchops niger) rely on cryptic behaviour to avoid detection by predators. After capture most individuals emit loud distress calls, and chicks crouched nearby often run just seconds after these calls begin. Experimental distress calls significantly increase the likelihood of running, regardless of whether a sibling or non-sibling call is used. Since chicks in close proximity are usually siblings, such distress notes could evolve through kin selection, even if disadvantageous to the caller. On the other hand, such calls may startle and distract a predator, providing the captive with an opportunity to escape.     

植物的亲缘选择

亲缘选择是指在一个随机交配群体中的个体基于亲缘关系而以一种非随机性的方式相互作用,其作用结果是亲缘个体得到更大的广义适合度。综述了亲缘选择和亲缘竞争两种观点以及各自的试验支持证据;分析了导致亲缘选择试验结果出现分歧的原因,认为这主要是由于对亲缘选择理解上的模糊以及试验设计的不严谨所致。植物间的亲缘选择研究不仅相对较少,对亲缘选择的机制研究更为欠缺,这就造成了目前对此问题在科学认识上出现不少盲点。综合前期研究,提出今后对亲缘选择的研究应该首先界定"亲缘"程度,同时改良试验设计方案,选择多种不同生境下的物种对亲缘选择进行深入研究,并且考虑环境因子对植物亲缘选择的影响。同时,对植物亲缘识别机制的研究应该从生理生化方面出发,通过定性定量地分析探索植物根系分泌物在植物亲缘识别中的作用和作用途径。     

Kin recognition in zebrafish: a 24-hour window for olfactory imprinting

Distinguishing kin from non-kin profoundly impacts the evolution of social behaviour. Individuals able to assess the genetic relatedness of conspecifics can preferentially allocate resources towards related individuals and avoid inbreeding. We have addressed the question of how animals acquire the ability to recognize kin by studying the development of olfactory kin preference in zebrafish (Danio rerio). Previously, we showed that zebrafish use an olfactory template to recognize even unfamiliar kin through phenotype matching. Here, we show for the first time that this phenotype matching is based on a learned olfactory imprinting process in which exposure to kin individuals on day 6 post fertilization (pf) is necessary and sufficient for imprinting. Larvae that were exposed to kin before or after but not on day 6 pf did not recognize kin. Larvae isolated from all contact with conspecifics did not imprint on their own chemical cues; therefore, we see no evidence for kin recognition through self-matching in this species. Surprisingly, exposure to non-kin odour during the sensitive phase of development did not result in imprinting on the odour cues of unrelated individuals, suggesting a genetic predisposition to kin odour. Urine-born peptides expressed by genes of the immune system (MHC) are important messengers carrying information about 'self' and 'other'. We suggest that phenotype matching is acquired through a time-sensitive learning process that, in zebrafish, includes a genetic predisposition potentially involving MHC genes expressed in the olfactory receptor neurons.     

Kin-recognition abilities and nepotism as a function of sociality

Despite widespread interest in kin selection and nepotism, relatively little is known about the perceptual abilities of animals to recognize their relatives. Here I show that a highly nepotistic species, Belding's ground squirrels (Spermophilus beldingi), produces odours from at least two sources that correlate with relatedness ('kin labels'), and that ground squirrels can use these odours to make accurate discriminations among never before encountered ('unfamiliar') kin. Recognition odours appear to vary linearly with relatedness, rather than in an all-or-none fashion, allowing precise estimates of kinship even among distant relatives. Thus S. beldingi are able to recognize their distant kin and male kin, even though they do not treat them preferentially. I also show that a closely related species (S. lateralis) similarly produces kin labels and discriminates among kin, although it shows no evidence of kin-directed behaviour. Thus, contrary to a commonly held assumption, kin favouritism and recognition abilities can evolve independently, depending on variation in the costs and benefits of nepotism for a given species.     

Inclusive fitness,asymmetric competition and kin selection in plants

The findings that some plants alter their competitive phenotype in response to genetic relatedness of its conspecific neighbour (and presumed competitor) has spurred an increasing interest in plant kin‐interactions. This phenotypic response suggests the ability to assess the genetic relatedness of conspecific competitors, proposing kin selection as a process that can influence plant competitive interactions. Kin selection can favour restrained competitive growth towards kin, if the fitness loss from reducing own growth is compensated by increased fitness in the related neighbour. This may lead to positive frequency dependency among related conspecifics with important ecological consequences for species assemblage and coexistence. However, kin selection in plants is still controversial. First, many studies documenting a plastic response to neighbour relatedness do not estimate fitness consequences of the individual that responds, and when estimated, fitness of individuals grown in competition with kin did not necessarily exceed that of individuals grown in non‐kin groups. Although higher fitness in kin groups could be consistent with kin selection, this could also arise from mechanisms like asymmetric competition in the non‐kin groups. Here we outline the main challenges for studying kin selection in plants taking genetic variation for competitive ability into account. We emphasize the need to measure inclusive fitness in order to assess whether kin selection occurs, and show under which circumstances kin selected responses can be expected. We also illustrate why direct fitness estimates of a focal plant, and group fitness estimates are not suitable for documenting kin selection. Importantly, natural selection occurs at the individual level and it is the inclusive fitness of an individual plant – not the mean fitness of the group – that can capture if a differential response to neighbour relatedness is favoured by kin selection.     

Temporal changes in kin structure through a population cycle in a territorial bird, the red grouse Lagopus lagopus scoticus

Populations of red grouse ( Lagopus lagopus scoticus ) undergo regular multiannual cycles in abundance. The 'kinship hypothesis' posits that such cycles are caused by changes in kin structure among territorial males producing delayed density-dependent changes in aggressiveness, which in turn influence recruitment and regulate density. The kinship hypothesis makes several specific predictions about the levels of kinship, aggressiveness and recruitment through a population cycle: (i) kin structure will build up during the increase phase of a cycle, but break down prior to peak density; (ii) kin structure influences aggressiveness, such that there will be a negative relationship between kinship and aggressiveness over the years; (iii) as aggressiveness regulates recruitment and density, there will be a negative relationship between aggressiveness in one year and both recruitment and density in the next; (iv) as kin structure influences recruitment via an affect on aggressiveness, there will be a positive relationship between kinship in one year and recruitment the next. Here we test these predictions through the course of an 8-year cycle in a natural population of red grouse in northeast Scotland, using microsatellite DNA markers to resolve changing patterns of kin structure, and supra-orbital comb height of grouse as an index of aggressiveness. Both kin structure and aggressiveness were dynamic through the course of the cycle, and changing patterns were entirely consistent with the expectations of the kinship hypothesis. Results are discussed in relation to potential drivers of population regulation and implications of dynamic kin structure for population genetics.     

Kin selection in Columbian ground squirrels: direct and indirect fitness benefits

Empirical and theoretical studies have supported kin selection by demonstrating nepotism or modelling its conditions and consequences. As an alternative, we previously found that female Columbian ground squirrels had greater direct fitness when more close kin were present. Extending those results, we used population matrix methods to calculate minimum estimates of individual fitness, estimated direct and indirect components of fitness, estimated inclusive fitness by adding the direct fitness (stripped of estimated influences of the social environment) and indirect fitness components together, and finally looked for inclusive fitness benefits of associations with close kin who seem to be 'genial neighbours'. We examined the estimated fitness of a sample of 35 females for which complete lifetimes were known for themselves, their mothers and their littermate sisters. Six of these females had no cosurviving adult close kin, and their direct fitness was significantly lower than 29 females with such kin (λ = 0.66 vs. λ = 1.23). The net fitness benefit of the presence of close kin was thus 0.57. The estimated indirect component of fitness through benefits to the direct fitness of close kin was 0.43. Thus, estimated inclusive fitness for females with cosurviving close kin (λ = 1.09) was significantly greater than that for females without surviving close kin (viz., λ = 0.66). The presence of closely related and philopatric female kin appeared to result in considerable fitness benefits for female ground squirrels, perhaps through the behavioural mechanisms of lowered aggression and other forms of behavioural cooperation.     

Strategies for determining kinship in wild populations using genetic data

Knowledge of kin relationships between members of wild animal populations has broad application in ecology and evolution research by allowing the investigation of dispersal dynamics, mating systems, inbreeding avoidance, kin recognition, and kin selection as well as aiding the management of endangered populations. However, the assessment of kinship among members of wild animal populations is difficult in the absence of detailed multigenerational pedigrees. Here, we first review the distinction between genetic relatedness and kinship derived from pedigrees and how this makes the identification of kin using genetic data inherently challenging. We then describe useful approaches to kinship classification, such as parentage analysis and sibship reconstruction, and explain how the combined use of marker systems with biparental and uniparental inheritance, demographic information, likelihood analyses, relatedness coefficients, and estimation of misclassification rates can yield reliable classifications of kinship in groups with complex kin structures. We outline alternative approaches for cases in which explicit knowledge of dyadic kinship is not necessary, but indirect inferences about kinship on a group‐ or population‐wide scale suffice, such as whether more highly related dyads are in closer spatial proximity. Although analysis of highly variable microsatellite loci is still the dominant approach for studies on wild populations, we describe how the long‐awaited use of large‐scale single‐nucleotide polymorphism and sequencing data derived from noninvasive low‐quality samples may eventually lead to highly accurate assessments of varying degrees of kinship in wild populations.