Effects Of Kinship Research Articles

Kinship, Family, and Gender Effects in the Ultimatum Game.

Kinship and reciprocity are two main predictors of altruism. The ultimatum game has been used to study altruism in many small-scale societies. We used the ultimatum game to examine effects of individuals' family and kin relations on altruistic behavior in a kin-based horticultural community in rural Dominica. Results show sex-specific effects of kin on ultimatum game play. Average coefficient of relatedness to the village was negatively associated with women's ultimatum game proposals and had little effect on men's proposals. Number of brothers in the village was positively associated with men's ultimatum game proposals and negatively associated with women's proposals. Similarly, presence of father in the village was associated with higher proposals by men and lower proposals by women. We interpret the effect of brothers on men's proposals as a consequence of local competition among brothers. We speculate that daughter-biased parental care in this community creates a sense of entitlement among women with brothers, which may explain the inverse relation between number of brothers and women's ultimatum game proposals. The pattern of results may be consistent with how matrifocality affects cultural models of fairness differently along gender and family lines.

Kin and Child Survival in Rural Malawi : Are Matrilineal Kin Always Beneficial in a Matrilineal Society?

This paper investigates the impact of kin on child survival in a matrilineal society in Malawi. Women usually live in close proximity to their matrilineal kin in this agricultural community, allowing opportunities for helping behavior between matrilineal relatives. However, there is little evidence that matrilineal kin are beneficial to children. On the contrary, child mortality rates appear to be higher in the presence of maternal grandmothers and maternal aunts. These effects are modified by the sex of child and resource ownership: female children and children in households where women, rather than men, own land suffer higher mortality rates in the presence of maternal kin. These modifiers suggest the detrimental effects of matrilineal kin may result from competition between such kin for resources. There are some positive effects of kin on child survival: the presence of elder siblings of both sexes is correlated with higher survival rates, and there is some weak evidence that paternal grandmothers may be beneficial to a child's survival chances. There is little evidence that any male kin, whether matrilineal or patrilineal, and including fathers, affect child mortality rates. This study highlights the importance of taking social and ecological context into account when investigating relationships between kin.

Neighborhood Effects and Women's Agency regarding Poverty and Patriarchy in a Turkish Slum

This paper aims to understand the interplay between the neighborhood (spatial) effects of poverty, ethnicity, kin, and patriarchy, and women's agency in the context of an inner-city slum in Ankara, the capital of Turkey. It is based on a field study that focuses on the experiences of women residents—that is, rural migrants known for their dependency on neighborhood spaces—and their grown-up daughters who were raised in the city. The neighborhood context—namely, the social and physical isolation of the site, the limited access to urban institutions, and the growing risk of crime—has a negative impact on women's lives, restraining but not determining women's agency. Women's struggle for agency in this context is contingent on other factors, including whether they live in ethnic clusters and whether their husbands are working, as well as urban experience and individual biography.

A genetic analysis of group movement in an isolated population of tree-roosting bats

Group fission is an important dispersal mechanism for philopatric adults. In Cypress Hills Interprovincial Park, Saskatchewan, tree-roosting big brown bats (Eptesicus fuscus) exhibit fission-fusion roosting behaviour. During 2004-2007, the majority of females previously resident to roosting area 1 (RA1) moved to a new roosting area (RA4). We examined how genetic relationships, inferred from data for microsatellite loci and mitochondrial DNA, influenced new roost area (RA) selection during 2006 when colony members were split between the RAs. We found that females who moved to RA4 had higher average relatedness than those that remained in RA1. We found that nearly all females belonging to matrilines with high average relatedness moved to RA4 while females from matrilines with low average relatedness were split between the two RAs. These results suggest that closely related maternal kin preferentially move to new RAs. However, daily roosting preferences within a RA are not based on genetic relationships probably because daily roosting associations between kin and non-kin are used to ensure adequate roost group size. Studying the effects of kinship on the fission and movements of groups not only enhances our understanding of social behaviour and population genetics but also informs conservation decisions.

Relatedness and Social Behaviors in Cercopithecus solatus

Inclusive fitness and kin selection theories predict that organisms will evolve biased behavior toward kin when the inclusive fitness benefits outweigh the costs of such behaviors. Researchers have long observed that primates bias their behavior toward relatives, particularly maternal kin. We examined the effect of kinship on social behaviors in a semifree-ranging colony of Cercopithecus solatus, a poorly studied forest guenon species. We used microsatellite loci and paternity analyses to determine the degree of relatedness between individuals, as well as kinship. Individuals biased some of their behavior according to relatedness. Specifically, related individuals are more spatially associated and less aggressive toward each other. When we replaced the relatedness coefficients with defined kin categories, Cercopithecus solatus seemed to behave preferentially toward maternal kin versus paternal kin. Even though the setting of the colony and the small sample size limit our conclusions, we discuss the potential implications of our finding for the study of the impact of kin selection in primate social relationships.

Kinship Influences Larval Growth and Metamorphic Traits of Bufo Scaber in a Context-dependent Manner

Studies on the effects of group composition (i.e., kin or mixed groups) on metamorphic traits (SVL, body mass, and duration of larval period) can provide insights into the evolution and maintenance of kin selection in anurans. Tadpoles of Bufo scaber from different sibships were reared at varying densities as sibling or mixed groups to determine the influence of kinship on metamorphic traits. Body mass, SVL, and larval period were similar among sibships reared in isolation. When 10 tadpoles were reared in 1- or 5-liter water, growth, larval period, and size at metamorphosis were comparable between sibling and mixed groups. In contrast, when the density of rearing was increased to 20 or 40 tadpoles per five liters, metamorph size was significantly lower in sibling groups than in mixed groups. Crowding negatively affected growth, body mass, and SVL in both kin and mixed groups. In mixed groups, metamorphosis was delayed, and metamorphs were larger than those reared as siblings at corresponding densities. Further, there was a large variation in body mass and larval period indicating, albeit indirectly, asymmetric competition among the mixed group individuals unlike in sibling groups. The present findings demonstrate that, in B. scaber, kinship plays a role in driving the metamorphic traits in a context-dependent manner. They also show that effects of kinship are expressed selectively under adverse ecological situations such as overcrowding.

Kin composition effects on reproductive competition among queenless honeybee workers

Kin selection and inclusive fitness theories predict that, in hopeless queenless (QL) groups, competition or cooperation will occur over male production among workers of different patrilines. Competition is expected to involve mutual inhibition of reproduction and to affect fertility advertisement. To examine kin effect on these phenomena, we studied QL groups of honeybee workers comprising three types of kin structure: groups composed of pure single patrilines, groups composed of three mixed patrilines (all originating from colonies headed by single-drone-inseminated queens), and control groups composed of bees originating from naturally mated queens. Global assessment of ovarian development, irrespective of patriline composition, revealed no differences among group types. In contrast, the performance of specific patrilines revealed that, in the three-mixed-patriline groups, some patrilines were reproductively suppressed compared to their performance when reared as a pure single patriline, resulting in an uneven share of reproduction. Analysis of the fertility signal produced by Dufour's gland revealed kin composition effects, which may reflect the bees' competitive efforts. Although patriline effects on worker reproductive superiority have been shown in QL colonies, we were able to investigate specific patriline performance both in competitive and noncompetitive situations here for the first time. The results are consistent with the hypothesis that reproductive and pheromonal competitions in QL groups are affected by the number of subfamilies populating a colony and that these act as coalitions. The results also emphasize that within-colony heterogeneity, in the form of multiple patrilines, has far-reaching consequences on social evolution.

Growing with kin does not bring benefits to tadpoles in a genetically impoverished amphibian population

The effect of intraspecific competition can be modified through the interaction with genetic relatedness among the competing individuals. Theory of kin selection predicts that organisms should modify their behaviour to increase the fitness of their relatives and consequently their inclusive fitness. However, in populations with low genetic variation, the recognition of kin and nonkin individuals could be compromised. In this study, we tested the influence of density and relatedness on larval development in a genetically impoverished population of the pool frog ( Rana lessonae Camerano, 1882), exposing individuals from four families to two densities and to competition by full-sibling and nonkin larvae. Larvae in high-density treatment were smaller than those in low-density treatment. No effect of kin, or interaction between density and kin, was detected. However, significant differences were detected in body size among the families and high heritability for size was found in both densities. Lack of variation in recognition alleles may explain the lack of kin effects on growth, whereas variation has been maintained in life-history traits either owing to their polygenic inheritance or owing to maternal effects.

Gene copy number analysis for family data using semiparametric copula model.

Gene copy number changes are common characteristics of many genetic disorders. A new technology, array comparative genomic hybridization (a-CGH), is widely used today to screen for gains and losses in cancers and other genetic diseases with high resolution at the genome level or for specific chromosomal region. Statistical methods for analyzing such a-CGH data have been developed. However, most of the existing methods are for unrelated individual data and the results from them provide explanation for horizontal variations in copy number changes. It is potentially meaningful to develop a statistical method that will allow for the analysis of family data to investigate the vertical kinship effects as well. Here we consider a semiparametric model based on clustering method in which the marginal distributions are estimated nonparametrically, and the familial dependence structure is modeled by copula. The model is illustrated and evaluated using simulated data. Our results show that the proposed method is more robust than the commonly used multivariate normal model. Finally, we demonstrated the utility of our method using a real dataset.

Yes, kin recognition in plants!

Klemens (2008) criticizes our evidence (Dudley & File 2007) that root allocation of plants depends on the kinship of neighbours. He objects to the statistical analysis, experimental setup and biomass results. Here we defend our statistical analysis and experimental setup, and show that Klemens misunderstands the study. We used analysis of covariance (ANCOVA), an accepted technique in plant allometry (Muller et al. 2000; Cahill 2003), to assess root allocation. Our study met the conditions of McCoy et al. (2006) for unbiased ANCOVA because the covariate, leaf mass, could be measured with more accuracy than the dependent variable, root mass and the covariate ranges are greatly overlapping (table 1). Our major result is robust to whether the model includes same or separate slopes and raw or transformed data. We presented the analysis that gave homoscedastic residuals and a better model fit. Table 1 Parameters for the separate regression lines taken from the ANCOVA in Dudley & File (2007). (The overall population mean for logleaf (figure 1a; Dudley & File 2007) was 0.863.) Littell et al. (2002) provides methodology for ANCOVA with separate slopes. Obtaining separate slopes indicates differences in allometric relationships (Muller et al. 2000). Thus, in finding a logleaf×kin effect, we found an effect of kin on root: leaf allometry. However, the results of separate slopes ANCOVA must be interpreted cautiously. When the regression slopes differ, the treatment effect depends on the covariate. The main effect only measures the difference between treatments at the y-intercept (Littell et al. 2002). To assess the difference between kin and strangers, we compared the least-squares means (lsmeans), which estimate the treatment effects at the overall population mean for the covariate (figure 1), a value within the range of all our treatments. Klemens (2008) incorrectly asserts that lsmeans are derived assuming a common slope, but their derivation is based on the separate slopes (example in figure 1). A more complete and complex comparison can be made by examining the fitted equations over the range of the variables (table 1). Figure 1 Scatter plot of a computer-generated dataset, where in group 1 (black filled circles), y=4x+error and in group 2 (open circles), y=5x+error. The dataset was analysed with a separate slopes ANCOVA (SAS PROC GLM), and the lsmeans (lsmean 1, black filled ... The role of pot size in explaining the apparent root competitor effects on root biomass and root allocation is a matter of current debate (Hess & De Kroon 2007). Since we can compare root allocation between groups of kin and groups of strangers within the same size pot, this is not a material objection to the basic result of kin recognition. The entangled roots of four plants could not be separated during harvesting, so we measured stand allocation rather than individual allocation. Klemens' (2008) remarks on the biomass variability and the lack of competitive effects indicate a misunderstanding of the study. We focused our experimental design on determining root allocation for groups of kin and strangers, not assessing fitness consequences. No competitive effects were expected because we kept density and average soil volume constant per plant. We used natural populations planted into naturally high density; both increase within-treatment size heterogeneity. We harvested when plants were undergoing strong vegetative growth at the start of flowering. Annual plants vary in life-history strategies; some bet hedge by reproducing early at the cost of vegetative growth. We do not find variation in performance surprising because performance is determined by many environmental and genetic factors. The variance in size increased our power to measure root allocation. Klemens (2008) claims that increased sibling biomass is a necessary consequence of kin recognition. This is not so. Others have measured fitness for groups of related and unrelated plants (Donohue 2003; Cheplick & Kane 2004), finding either increased fitness in sibling groups, suggesting kin selection or increased fitness in stranger groups, interpreted as niche partitioning. Both processes could co-occur. But no inferences concerning fitness should be made because we measured the plants at an early life-history stage, and there was no statistically significant size difference between kin and strangers (figure 1b; Dudley & File 2007). We found kin recognition in one plant species. The best challenge to this result is further empirical work. Is the result methodology specific? Does it occur in other species, and in other traits? What are its fitness consequences?

Integrating cooperative breeding into theoretical concepts of cooperation

In cooperative breeding systems, some individuals help to raise offspring that are not their own. While early explanations for such altruistic behaviour were predominantly based on kin selection, recent evidence suggests that direct benefits may be important in the maintenance of cooperation. To date, however, discussions of cooperative breeding have made little reference to more general theories of cooperation between unrelated individuals (while these theories rarely address cooperative breeding). Here, we attempt to integrate the two fields. We identify four key questions that can be used to categorise different mechanisms for the maintenance of cooperative behaviour: (1) whether or not individuals invest in others; (2) whether or not this initial investment elicits a return investment by the beneficiary; (3) whether the interaction is direct, i.e. between two partners, or indirect (involving third parties) and (4) whether only actions that increase the fitness of the partner or also fitness reducing actions (punishment) are involved in the interaction. Asking these questions with regards to concepts in the literature on cooperative breeding, we found that (a) it is often straightforward to relate these concepts to general mechanisms of cooperation, but that (b) a single term (such as 'pay-to-stay', 'group augmentation' or 'prestige') may sometimes subsume two or more distinct mechanisms, and that (c) at least some mechanisms that are thought to be important in cooperative breeding systems have remained largely unexplored in the theoretical literature on the evolution of cooperation. Future theoretical models should incorporate asymmetries in power and pay off structure caused for instance by dominance hierarchies or partner choice, and the use of N-player games. The key challenges for both theoreticians and empiricists will be to integrate the hitherto disparate fields and to disentangle the parallel effects of kin and non-kin based mechanisms of cooperation.

Variable participation in the defense of communal feeding territories by blue monkeys in the Kakamega Forest, Kenya

Abstract While blue monkey groups often defend feeding territories against their neighbours, group members do not participate equally. Data spanning 5 years and 5 wild groups were used to address factors that might explain variable participation, both across age-sex classes and among individual adult females. Adult females participated most, although there was a 9-fold difference between those individuals who participated most and least. Juvenile participation increased with age, but female juveniles participated more than males in each cohort. Male juveniles reduced participation as they approached the age of natal emigration. In general, it seems that adult participation patterns are acquired gradually during ontogeny. Among adult females, those with infants participated less than those without infants, and higher-ranking females participated more than lower-rankers. The presence of matrilineal kin in the group did not generally affect participation by adult females. Age-sex class differences and the effect of infant presence can be explained in terms of relative costs and benefits to participation. The lack of a kinship effect was unexpected. The rank effect was also unanticipated, given that rank does not predict reproductive success in this species. High-ranking females may face lower costs, offer staying incentives to lower-ranked females, or trade services with them.

Gender, Land and Local Heterogeneity

This paper aims to demonstrate that China's land policy and land law are altered in social interactions between different actors. Such social processes have led to the gendering of rural land tenure practices, but also a highly heterogeneous situation with regard to land tenure. This paper aims to demonstrate that the combined effect of marital relations, kinship, social network and low political representation of women in the community often results in the deprivation of women's land rights and many women are becoming landless. However, our field research shows that there are also cases where women are able to get access to land if they live in communities where land is still subject to redistribution or readjustment, or where women have political representation and gender-awareness training.

Between‐clutch interactions affect a benefit of group feeding for pipevine swallowtail larvae

Abstract. 1. In California, early instar larvae of the pipevine swallowtail (Battus philenor) develop at an accelerated rate when feeding in large groups compared with small groups due to a plant‐mediated response to feeding group size. Larvae benefit from accelerated growth because the time larvae remain in early stages, where mortality is highest, is reduced. Occasionally, multiple clutches are laid on the same plant stem. Clutch size modification by females ovipositing on plant with previously laid clutches and the effect of kinship and group size on larval behaviour was examined. The direct and indirect interactions between clutches were investigated to determine if group size and time between clutch establishment affects the performance of early instar larvae.2. Larger groups consume the young foliage more quickly and develop at an accelerated rate compared with smaller groups. Older foliage available to later clutches is an inferior food resource compared with younger foliage.3. There was no evidence that females adjust clutch size in response to the presence of conspecific clutches.4. Second groups of larvae readily joined previously established feeding groups. There were no observed behavioural differences between sibling and mixed‐family groups.5. The effect of a second group on the growth of the initial group was dependent on the size of both groups and the time interval between the arrival of the two groups.6. Accelerated growth associated with larger feeding aggregations was absent when these groups were introduced to plants with previously established groups.7. It is beneficial for ovipositing females to avoid plants with previously laid clutches because direct and indirect interactions with established clutches compromises larval performance.

Exchange, affiliation, and protective interventions in semifree-ranging brown capuchin monkeys (Cebus apella)

The "social intelligence" hypothesis proposes that intelligence evolved as a consequence of the need for behavioral maneuvering to deal with the complexities of social life. As a result, coalitions have received considerable attention. Here we present the patterns of coalitionary behavior observed in a semifree-ranging group of Cebus apella and explore the effects of kinship, spatial proximity, and rank. In contrast to descriptions of Old World monkeys and to some descriptions of capuchins, kinship did not influence the pattern of coalitionary behavior, although individuals tended to help those that remained in close proximity. Rank had the greatest influence on coalitions: those that interfered in conflicts (often the alpha) were higher ranking than both contestants and supported the most subordinate (younger) interactant. However, rank did not influence the coalitionary support when conflicts involved only adults. We found no evidence that individuals were making use of triadic knowledge, and most of the coalitions can best be described as protective interventions involving immatures. The overall low rate of coalitions may be due to a period of social stability.

GENETIC AND HOUSEHOLD RISK FACTORS FOR SCHISTOSOMA JAPONICUM INFECTION IN THE PRESENCE OF LARGER SCALE ENVIRONMENTAL DIFFERENCES IN THE MOUNTAINOUS TRANSMISSION AREAS OF CHINA

Schistosoma japonicum egg excretion and kinship relationship data from 13 endemic villages in the mountainous transmission area near Xichang, in Sichuan province, China, were analyzed via a variance components methodology to assess the relative contribution of kinship, shared household, and shared village to the risk of infection. Large intervillage differences in egg counts exist in this region due to differences in transmission potential related to environmental differences in snail density and agricultural practices. After accounting for these intervillage differences, there was no kinship or household effect on egg excretion. This reinforces earlier findings that suggest environmental factors dominate risk in this region.

Association between social relationships and survival of Swiss octogenarians. A five-year prospective, population-based study

Data from the literature reveal the contrasting influences of family members and friends on the survival of old adults. On one hand, numerous studies have reported a positive association between social relationships and survival. On the other, ties with children may be associated with an increased risk of disability, whereas ties with friends or other relatives tend to improve survival. A five-year prospective, population-based study of 295 Swiss octogenarians tested the hypothesis that having a spouse, siblings or close friends, and regular contacts with relatives or friends are associated with longer survival, even at a very old age. Data were collected through individual interviews, and a Cox regression model was applied to assess the effects of kinship and friendship networks on survival, after adjusting for socio-demographic and health-related variables. Our analyses indicate that the presence of a spouse in the household is not significantly related to survival, whereas the presence of siblings at baseline improves the oldest old's chances of surviving five years later. Moreover, the existence of close friends is a central component in the patterns of social relationships of oldest adults, and one which is significantly associated with survival. Overall, the protective effect of social relationships on survival is more related to the quality of those relationships (close friends) than to the frequency of relationships (regular contacts). We hypothesize that the existence of siblings or close friends may beneficially affect survival, due to the potential influence on the attitudes of octogenarians regarding health practices and adaptive strategies.

Helpful grandmothers in rural Ethiopia: A study of the effect of kin on child survival and growth

Kin selection and parental investment theories state that, in highly social species, such as humans, individuals can increase their inclusive fitness by extending support to their relatives. Here, we document patterns of kin support in a rural Ethiopian community, where postmarital residence practices provide differential access to relatives. Using demographic, anthropometric, and behavioral data collected from four villages we are able to (a) identify the effects of the presence of kin on child mortality and growth patterns and (b) provide detailed information on the role of relatives within the household. Mortality analyses indicate that grandmothers had a positive effect on child survival. Anthropometric data reveal that maternal grandmothers had a particularly beneficial effect on child height, but paternal grandmothers less so. Time allocation data suggest that grandmothers continued to visit their daughters' households, irrespective of postmarital residence, where they relieved their daughters of heavy domestic tasks rather than helping with direct grandchild care. Matrilocal postmarital residence was associated with improved child survival, although children in matrilocal households were actually smaller. This may be due to wealth effects, increased competition between siblings, or higher survival of smaller infants in matrilocal households.

Kinship, Gender & Migration from a Rural Caribbean Community

Emigration from developing countries may be influenced by kinship, which has different effects on men and women. A strong family at home may inhibit migration, and kin living abroad may encourage it. This study examines effects of kin on odds of migration for men (N=200) and women (N=220) from a rural community in the Commonwealth of Dominica. Multiple logistic regression showed that women were more likely than men to migrate. Number of matrilateral kin in the community was associated with women's migration but not with men's. Maternal grandmothers resident in the community were associated with decreased odds that women migrate.

Effects of male kinship and agonistic behaviour on reproduction and odour preferences of female house mice, Mus domesticus

In gregarious species, males may wound or kill females during intermale contest competition, which directly affects females fitness. However, male–male agonistic encounters may also have more subtle effects on females by creating a stressful social environment in which females live. We examined whether male–male aggression affects female fitness and odour preference in house mice. We tested (1) whether pairs of brothers would be less likely to fight than pairs of nonbrothers; (2) whether females housed with two males that were brothers would have higher reproductive success than females housed with two males that were not brothers and (3) whether females would show a preference for the odours of brother or nonbrother pairs. Males that were brothers were less aggressive towards each other than were nonbrothers, and females housed with males that were brothers produced significantly more litters than those housed with males that were not brothers. Females did not show a preference for the odours of brothers or nonbrothers, but they did prefer odours of less aggressive pairs of males. These findings suggest that while contest competition favours fighting among males, female choice and kin selection favour tolerance.