Inbreeding depresses altruism in a cooperative society

In some animal species, individuals regularly breed with relatives, including siblings and parents. Given the high fitness costs of inbreeding, evolutionary biologists have found it challenging to understand the persistence of these inbred societies in nature. One appealing but untested explanation is that early life care may create a benign environment that offsets inbreeding depression, allowing inbred societies to evolve. We test this possibility using 21 years of data from a wild cooperatively breeding mammal, the banded mongoose, a species where almost one in ten young result from close inbreeding. We show that care provided by parents and alloparents mitigates inbreeding depression for early survival. However, as adults, inbred individuals provide less care, reducing the amount of help available to the next generation. Our results suggest that inbred cooperative societies are rare in nature partly because the protective care that enables elevated levels of inbreeding can be reduced by inbreeding depression

City limits: sexual politics and the new urban left in 1980s Sheffield

In the 1980s Sheffield had a vibrant political milieu made up of labour and new social movement activists who were variously supported by a left-wing Labour-led City Council. Sheffield City Council developed their own form of local socialism which fed into the ideas of the new urban left and left-wing thinkers like Stuart Hall and his contemporaries at Marxism Today. Sheffield City Council was interested in uniting class and identity politics in a form of political renewal; however, both the Council and the city’s dominant labour movement preferred to focus on material concerns. Sheffield’s politics was energetic but inchoate and messy. Whilst the Council and labour movement made supportive links with peace, anti-apartheid and women’s movements, certain groups were left on the outside. Uniting class and identity over gay politics proved a bridge too far. This article explores Sheffield’s gay politics to show how left-wing solidarity in the city broke down. Sheffield’s new urban left found its limits in the arena of gay politics

A double pedigree reveals genetic but not cultural inheritance of cooperative personalities in wild banded mongooses

Personality traits, such as the propensity to cooperate, are often inherited from parents to offspring, but the pathway of inheritance is unclear. Traits could be inherited via genetic or parental effects, or culturally via social learning from role models. However, these pathways are difficult to disentangle in natural systems as parents are usually the source of all of these effects. Here, we exploit natural 'cross fostering' in wild banded mongooses to investigate the inheritance of cooperative behaviour. Our analysis of 800 adult helpers over 21 years showed low but significant genetic heritability of cooperative personalities in males but not females. Cross fostering revealed little evidence of cultural heritability: offspring reared by particularly cooperative helpers did not become more cooperative themselves. Our results demonstrate that cooperative personalities are not always highly heritable in wild, and that the basis of behavioural traits can vary within a species (here, by sex).Peer reviewe

Surface-Energy Control and Characterization of Nanoparticle Coatings

Accurate and reproducible measurement of the structure and properties of high-value nanoparticles is extremely important for their commercialization. A significant proportion of engineered nanoparticle systems consist of some form of nominally core\u2013shell structure, whether by design or unintentionally. Often, these do not form an ideal core\u2013shell structure, with typical deviations including polydispersity of the core or shell, uneven or incomplete shells, noncentral cores, and others. Such systems may be created with or without intent, and in either case an understanding of the conditions for formation of such particles is desirable. Precise determination of the structure, composition, size, and shell thickness of such particles can prove challenging without the use of a suitable range of characterization techniques. Here, the authors present two such polymer core\u2013shell nanoparticle systems, consisting of polytetrafluoroethylene cores coated with a range of thicknesses of either polymethylmethacrylate or polystyrene. By consideration of surface energy, it is shown that these particles are expected to possess distinctly differing coating structures, with the polystyrene coating being incomplete. A comprehensive characterization of these systems is demonstrated, using a selection of complementary techniques including scanning electron microscopy, scanning transmission electron microscopy, thermogravimetric analysis, dynamic light scattering, differential centrifugal sedimentation, and X-ray photoelectron spectroscopy. By combining the results provided by these techniques, it is possible to achieve superior characterization and understanding of the particle structure than could be obtained by considering results separately

A high-quality pedigree and genetic markers both reveal inbreeding depression for quality but not survival in a cooperative mammal

Inbreeding depression, the reduced fitness of offspring of closely related parents, is commonplace in both captive and wild populations and has important consequences for conservation and mating system evolution. However, because of the difficulty of collecting pedigree and life history data from wild populations, relatively few studies have been able to compare inbreeding depression for traits at different points in the life cycle. Moreover, pedigrees give the expected proportion of the genome that is identical by descent (IBDg) whereas in theory with enough molecular markers realised IBDg can be quantified directly. We therefore investigated inbreeding depression for multiple life-history traits in a wild population of banded mongooses using pedigree-based inbreeding coefficients (fped) and standardised multilocus heterozygosity (sMLH) measured at 35-43 microsatellites. Within an information theoretic framework, we evaluated support for either fped or sMLH as inbreeding terms and used sequential regression to determine whether the residuals of sMLH on fped explain fitness variation above and beyond fped. We found no evidence of inbreeding depression for survival, either before or after nutritional independence. By contrast, inbreeding was negatively associated with two quality related traits, yearling body mass and annual male reproductive success. Yearling body mass was associated with fped but not sMLH, while male annual reproductive success was best explained by both fped and residual sMLH. Thus, our study not only uncovers variation in the extent to which different traits show inbreeding depression, but also reveals trait-specific differences in the ability of pedigrees and molecular markers to explain fitness variation and suggests that for certain traits genetic markers may capture variation in realised IBDg above and beyond the pedigree expectation. This article is protected by copyright. All rights reserved

Data collection and storage in long-term ecological and evolutionary studies : The Mongoose 2000 system

Studying ecological and evolutionary processes in the natural world often requires research projects to follow multiple individuals in the wild over many years. These projects have provided significant advances but may also be hampered by needing to accurately and efficiently collect and store multiple streams of the data from multiple individuals concurrently. The increase in the availability and sophistication of portable computers (smartphones and tablets) and the applications that run on them has the potential to address many of these data collection and storage issues. In this paper we describe the challenges faced by one such long-term, individual-based research project: the Banded Mongoose Research Project in Uganda. We describe a system we have developed called Mongoose 2000 that utilises the potential of apps and portable computers to meet these challenges. We discuss the benefits and limitations of employing such a system in a long-term research project. The app and source code for the Mongoose 2000 system are freely available and we detail how it might be used to aid data collection and storage in other long-term individual-based projects.Peer reviewe

A long postreproductive life span is a shared trait among genetically distinct killer whale populations.

The extended female postreproductive life span found in humans and some toothed whales remains an evolutionary puzzle. Theory predicts demographic patterns resulting in increased female relatedness with age (kinship dynamics) can select for a prolonged postreproductive life span due to the combined costs of intergenerational reproductive conflict and benefits of late-life helping. Here, we test this prediction using >40 years of longitudinal demographic data from the sympatric yet genetically distinct killer whale ecotypes: resident and Bigg's killer whales. The female relatedness with age is predicted to increase in both ecotypes, but with a less steep increase in Bigg's due to their different social structure. Here, we show that there is a significant postreproductive life span in both ecotypes with >30% of adult female years being lived as postreproductive, supporting the general prediction that an increase in local relatedness with age predisposes the evolution of a postreproductive life span. Differences in the magnitude of kinship dynamics however did not influence the timing or duration of the postreproductive life span with females in both ecotypes terminating reproduction before their mid-40s followed by an expected postreproductive period of about 20 years. Our results highlight the important role of kinship dynamics in the evolution of a long postreproductive life span in long-lived mammals, while further implying that the timing of menopause may be a robust trait that is persistent despite substantial variation in demographic patterns among populations

Mixture models as a method for comparative sociality: social networks and demographic change in resident killer whales

In studies of social behaviour, social bonds are usually inferred from rates of interaction or association. This approach has revealed many important insights into the proximate formation and ultimate function of animal social structures. However, it remains challenging to compare social structure between systems or time-points because extrinsic factors, such as sampling methodology, can also influence the observed rate of association. As a consequence of these methodological challenges, it is difficult to analyse how patterns of social association change with demographic processes, such as the death of key social partners. Here we develop and illustrate the use of binomial mixture models to quantitatively compare patterns of social association between networks. We then use this method to investigate how patterns of social preferences in killer whales respond to demographic change. Resident killer whales are bisexually philopatric, and both sexes stay in close association with their mother in adulthood. We show that mothers and daughters show reduced social association after the birth of the daughter’s first offspring, but not after the birth of an offspring to the mother. We also show that whales whose mother is dead associate more with their opposite sex siblings and with their grandmother than whales whose mother is alive. Our work demonstrates the utility of using mixture models to compare social preferences between networks and between species. We also highlight other potential uses of this method such as to identify strong social bonds in animal populations