The Department of Biological Sciences has an expanding research base, which, in addition to providing leading researchers of national and international standing in these areas, most importantly underpins the delivery of teaching. Research in Biological Sciences at Chester can be divided into three broad groups of expertise, namely Animal Behaviour and Conservation, Food Nutrition and Health, and Stress and Disease.

Recent Submissions

  • Female clustering in cockroach aggregations – a case of social niche construction?

    Stanley, Christina; Preziosi, Richard F.; Liddiard Williams, H.; University of Chester, University of Manchester, Manchester Metropolitan University (Wiley, 2018)
    Individuals in groups can suffer costs through interactions with adversarial or unknown conspecifics. Social niche construction allows individuals to buffer such potential costs by only engaging in preferred associations. This may be particularly beneficial in insect aggregations, which are often large and highly fluid. However, little is known regarding the structuring of such aggregations. Here we use social network analyses to test for fine-scale social structure in resting aggregations of the sub-social cockroach Diploptera punctata and to explore the social pressures that contribute towards such structure. We showed that females were significantly more gregarious than males and formed the core of the proximity network, thus demonstrating a higher level of social integration. This fine-scale structure is likely to result from females displacing males; females initiated most displacements whilst males received the majority. We explain this behaviour in terms of social niche construction by showing that females received significantly fewer approaches and investigations at more female-biased local sex ratios. We therefore suggest that female social clustering occurs in this, and presumably other, species to reduce potential costs associated with male harassment. This demonstrates how social niche construction can lead to higher level social structure; we suggest this approach could be used across a range of species in order to improve our understanding of the evolution of sociality.
  • Extraction, identification and biological activities of saponins in sea cucumber Pearsonothuria graeffei

    Khattaba, Rafat A.; Elbandy, Mohamed; Lawrence, Andrew; Paget, Tim; Rae-Rho, Jung; Binnasera, Yaser S.; Alih, Imran; Taibah University; Suez Canal University; Jizan University; Alarish University; University of Chester; Sunderland University; Kunsan National University; Central University, New Delhi (Bentham Science, 2018-04-01)
    Secondary metabolism in marine organisms produced a diversity of biological important natural compounds which are unpresented in terrestrial species. Sea cucumbers belong to the invertebrate Echinodermata and are famous for their nutraceutical, medical and food values. They are known for possession triterpenoid glycosides (saponins) with various ecological roles. The current work aimed to separate, identify and test various biological activities (anti-bacterial, antifungal, antileishmanial and anticancer properties) of saponins produced by the holothurian Pearsonothuria graeffei from the Red Sea, Egypt.
  • Direct and indirect causal effects of heterozygosity on fitness-related traits in Alpine ibex

    Brambilla, Alice; Biebach, Iris; Bassano, Bruno; Bogliani, Giuseppe; von Hardenberg, Achaz; Università di Pavia, Italy; University of Zurich, Switzerland; Gran Paradiso National Park, Italy; University of Chester, UK (The Royal Society, 2015-01-07)
    Heterozygosity–fitness correlations (HFCs) are a useful tool to investigate the effects of inbreeding in wild populations, but are not informative in distinguishing between direct and indirect effects of heterozygosity on fitness-related traits. We tested HFCs in male Alpine ibex (Capra ibex) in a free-ranging population (which suffered a severe bottleneck at the end of the eighteenth century) and used confirmatory path analysis to disentangle the causal relationships between heterozygosity and fitness-related traits. We tested HFCs in 149 male individuals born between 1985 and 2009. We found that standardized multi-locus heterozygosity (MLH), calculated from 37 microsatellite loci, was related to body mass and horn growth, which are known to be important fitness-related traits, and to faecal egg counts (FECs) of nematode eggs, a proxy of parasite resistance. Then, using confirmatory path analysis, we were able to show that the effect of MLH on horn growth was not direct but mediated by body mass and FEC. HFCs do not necessarily imply direct genetic effects on fitness-related traits, which instead can be mediated by other traits in complex and unexpected ways.
  • Helpers influence on territory use and maintenance in Alpine marmot groups

    Pasquaretta, Cristian; Busia, Laura; Ferrari, Caterina; Bogliani, Giuseppe; Reale, Denis; von Hardenberg, Achaz; University of Pavia, Universiteé du Quebec a Montreal, Gran Paradiso National Park (2015-04-22)
    In social mammals, territory size and shape vary according to the number and strength of neighbour individuals competing for resources. Two main theories have been proposed to explain this variability: the Group Augmentation (GA) and the realized Resource Holding Potential (rRHP) hypotheses. The first states that the outcome of the interactions among groups depends on the total number of individuals in the group while the second states that only the number of animals directly involved in intergroup competition determines this outcome. We collected data on space use of individually tagged Alpine marmots ( Marmota marmota), a cooperative breeding species that overlaps part of its territory with neighbouring groups. In accordance with the rRHP hypothesis, we found that groups having higher proportion of helpers, rather than higher total number of individuals, had lower percentage of the territory overlapping with neighbouring groups and a larger area available for individual exclusive use.
  • Higher risk of gastrointestinal parasite infection at lower elevation suggests possible constraints in the distributional niche of Alpine marmots

    Zanet, Stefania; Miglio, Giacomo; Ferrari, Caterina; Bassano, Bruno; Ferroglio, Ezio; von Hardenberg, Achaz; Università di Torino; Gran Paradiso National Park; University of Chester (Public Library of Science, 2017-08-01)
    Alpine marmots Marmota marmota occupy a narrow altitudinal niche within high elevation alpine environments. For animals living at such high elevations where resources are limited, parasitism represents a potential major cost in life history. Using occupancy models, we tested if marmots living at higher elevation have a reduced risk of being infected with gastrointestinal helminths, possibly compensating the lower availability of resources (shorter feeding season, longer snow cover and lower temperature) than marmots inhabiting lower elevations. Detection probability of eggs and oncospheres of two gastro-intestinal helminthic parasites, Ascaris laevis and Ctenotaenia marmotae, sampled in marmot feces, was used as a proxy of parasite abundance. As predicted, the models showed a negative relationship between elevation and parasite detectability (i.e. abundance) for both species, while there appeared to be a negative effect of solar radiance only for C. marmotae. Site-occupancy models are used here for the first time to model the constrains of gastrointestinal parasitism on a wild species and the relationship existing between endoparasites and environmental factors in a population of free-living animals. The results of this study suggest the future use of site-occupancy models as a viable tool to account for parasite imperfect detection in ecoparasitological studies, and give useful insights to further investigate the hypothesis of the contribution of parasite infection in constraining the altitudinal niche of Alpine marmots.
  • Involvement of recreational anglers in the eradication of alien brook trout from high altitude lakes

    Tiberti, R.; Ottino, M.; Brighenti, S.; Iacobuzio, R.; Rolla, M.; von Hardenberg, Achaz; Bassano, B.; Gran Paradiso National Park, University of Pavia, Università degli studi di Trento, Fondazione E. Mach, Università degli Studi di Milano, Swansea University, University of Chester (Gran Paradiso National Park Agency, 2017)
    Stocking programmes for recreational angling are primarily responsible for the spread and ecological impact of introduced sh in high-altitude, originally shless lakes. In 2013, the Gran Paradiso National Park started an eradication campaign of brook trout by intensive gill-netting. Local anglers were invited to attend two angling sessions to start the eradication before gill-netting in an experimental lake, as part of an education action devoted to these critical stakeholders. The angling sessions turned out to be a valuable help for the eradication campaign and the aim of this study is to report on the outcomes of these angling sessions. Angling techniques were highly size-selective, removing a substantial part of the adult population and of the sh biomass, but their contribution to the eradication of small sh (<15cm) was irrelevant. Therefore, angling cannot completely eradicate age-structured populations. However, there is scope to use angling sessions as a support for eradication campaigns and as an emergency measure for recent sh introduc- tions. Similar actions should be considered whenever a sh eradication programme is planned. These ndings, however, do not imply a general endorsement for angling within protected areas.
  • Predicting the potential distribution of the Endangered huemul deer Hippocamelus bisulcus in North Patagonia

    Quevedo, Paloma; von Hardenberg, Achaz; Pastore, Hernan; Alvarez, Jose; Corti, Paulo; Ernst-Moritz-Arndt Universität, Greifswald, Germany; University of Chester; Administración de Parques Nacionales, Bariloche, Argentina;Corporación Nacional Forestal, Chile, Universidad Austral de Chile (2017-04)
    Habitat loss is one of the main threats to wildlife, particularly large mammals. Estimating the potential distribution of threatened species to guide surveys and conservation is crucial, primarily because such species tend to exist in small fragmented populations. The Endangered huemul deer Hippocamelus bisulcus is endemic to the southern Andes of Chile and Argentina. Although the species occurs in the Valdivian Ecoregion, a hotspot for biodiversity, we have no information on its occupancy and potential distribution in this region. We built and compared species distribution models for huemul using the maximum entropy approach, using 258 presence records and sets of bioclimatic and geographical variables as predictors, with the objective of assessing the potential distribution of the species in the Valdivian Ecoregion. Annual temperature range and summer precipitation were the predictive variables with the greatest influence in the best-fitting model. Approximately 12,360 km2 of the study area was identified as suitable habitat for the huemul, of which 30% is included in the national protected area systems of Chile and Argentina. The map of potential distribution produced by our model will facilitate prioritization of future survey efforts in other remote and unexplored areas in which huemul have not been recorded since the 1980s, but where there is a high probability of their occurrence.
  • Thermal niche predicts recent changes in range size for bird species

    Scridel, D.; Bogliani, G.; Pedrini, P.; Iemma, A.; von Hardenberg, Achaz; Brambilla, M.; Museo delle Scienze, Trento; University of Pavia, University of Chester, Fondzione Lombardia per l'Ambiente (Inter-Research Science Center (IR), 2017-08-30)
    Species’ distributions are strongly affected by climate, and climate change is affecting species and populations. Thermal niches are widely used as proxies for estimating thermal sensitivity of species, and have been frequently related to community composition, population trends and latitudinal/elevational shifts in distribution. To our knowledge, no work has yet explored the relationship between thermal niche and change in range size (changes in the number of occupied spatial units over time) in birds. In this study, we related a 30 yr change in range size to species thermal index (STI: average temperature at occurrence sites) and to other factors (i.e. birds’ associated habitats, body mass, hunting status) potentially affecting bird populations/range size. We analysed trends of breeding bird range in Italy for a suite of poorly studied cold-adapted animals potentially sensitive to global warming, and for a related group of control species taxonomically similar and with comparable mass but mainly occurring at lower/warmer sites. We found a strong positive correlation between change in range size and STI, confirming that recent climatic warming has favoured species of warmer climates and adversely affected species occupying colder areas. A model including STI and birds’ associated habitats was not so strongly supported, with forest species performing better than alpine open habitat and agricultural ones. In line with previous works highlighting effects of recent climate change on community composition, species’ population trends and poleward/upward distributional shifts, we found STI to be the most important predictor of change in range size variation in breeding birds.
  • MODIS time series contribution for the estimation of nutritional properties of alpine grassland

    Ranghetti, Luigi; Bassano, Bruno; Bogliani, Giuseppe; Polmonari, Alberto; Formigoni, Andrea; Stendardi, Laura; von Hardenberg, Achaz; Consiglio Nazionale delle Ricerche; Università di Pavia; Parco Nazionale Gran Paradiso; Università di Bologna; Università di Firenze; University of Chester (Taylor & Francis, 2017-02-17)
    Despite the Normalised Difference Vegetation Index (NDVI) has been used to make predictions on forage quality, its relationship with bromatological field data has not been widely tested. This relationship was investigated in alpine grasslands of the Gran Paradiso National Park (Italian Alps). Predictive models were built using remotely sensed derived variables (NDVI and phenological information computed from MODIS) in combination with geo-morphometric data as predictors of measured biomass, crude protein, fibre and fibre digestibility, obtained from 142 grass samples collected within 19 experimental plots every two weeks during the whole 2012 growing season. The models were both cross-validated and validated on an independent dataset (112 samples collected during 2013). A good predictability ability was found for the estimation of most of the bromatological measures, with a considerable relative importance of remotely sensed derived predictors; instead, a direct use of NDVI values as a proxy of bromatological variables appeared not to be supported.
  • Impact of tank background on the welfare of the African clawed frog, Xenopus laevis (Daudin)

    Holmes, Andrew M.; Emmans, Christopher J.; Jones, Niall; Coleman, Robert C.; Smith, Tessa E.; Hosie, Charlotte A.; University of Chester (Elsevier, 2016-09-14)
    The captive environment of a laboratory animal can profoundly influence its welfare and the scientific validity of research produced. The African clawed frog (Xenopus laevis) is a common model organism, however current husbandry guidelines lack supporting quantitative evidence. The visual environment is a fundamental aspect of a captive animal’s housing and may affect a number of physiological and behavioural responses. This is particularly important for species such as X. laevis where cryptic camouflage is a fundamental defence mechanism. Here male (n = 16) and female (n = 20) X. laevis were housed in tanks with ecologically relevant (black) and non-relevant (white) background colours and physiological and behavioural responses observed. Higher levels of water-borne corticosterone were observed in tanks with a white background compared to a black background in females (p = 0.047). Increased atypical active behaviours (Swimming: p = 0.042; Walling: p = 0.042) and a greater degree of body mass loss (p < 0.001) were also observed in the white background condition. Together these responses are indicative of increased stress of X. laevis when housed in tanks with a non-ecologically relevant background compared to an ecologically relevant background and suggest refined tank background colour may improve welfare in this species.
  • Effects of transportation, transport medium and re-housing on Xenopus laevis (Daudin)

    Holmes, Andrew M.; Emmans, Christopher J.; Coleman, Robert C.; Smith, Tessa E.; Hosie, Charlotte A.; University of Chester (Elsevier, 2018-03-12)
    Understanding the immediate and longer-term effects of transportation and re-housing in a laboratory species is crucial in order to refine the transfer process, enable the optimal introduction of new animals to a novel environment and to provide a sufficient acclimatisation period before usage. Whilst consideration of animal welfare in most model vertebrate species has received attention, little quantitative evidence exists for the optimal care of the common laboratory amphibian Xenopus laevis. Techniques for the non-invasive welfare assessment of amphibians are also limited and here a non-invasive physiological assay was developed to investigate the impacts of transportation, transport medium and re-housing on X. laevis. First the impacts of transportation and transport medium (water, damp sponge or damp sphagnum moss) were investigated. Transportation caused an increase in waterborne corticosterone regardless of transport medium. Frogs transported in damp sphagnum moss also had a greater decrease in body mass in comparison to frogs not transported, suggesting that this is the least suitable transport medium for X. laevis. Next the prolonged impacts of transportation and re-housing were investigated. Frogs were transported between research facilities with different housing protocols. Samples were collected prior to and immediately following transportation, as well as 1 day, 7 days and 35 days after re-housing. Water-borne corticosterone increased following transportation and remained high for at least 7 days, decreasing to baseline levels by 35 days. Body mass decreased following transportation and remained lower than baseline levels across the entire 35 day observation period. These findings suggest the process of transportation and re-housing is stressful in this species. Together these findings have important relevance for both improving animal welfare and ensuring optimal and efficient scientific research.
  • Measuring physiological stress in the common marmoset (Callithrix jacchus): Validation of a salivary cortisol collection and assay technique

    Ash, Hayley; Smith, Tessa E.; Knight, Simon; Buchanan-Smith, Hannah M.; University of Stirling; University of Chester; Defence Science and Technology Laboratory (Dstl); University of Wisconsin (Elsevier, 2017-12-15)
    Cortisol levels are often used as a physiological measure of the stress response in captive primates, with non-invasive measures of this being an important step in welfare assessment. We report a method of collecting saliva samples voluntarily from unrestrained captive common marmosets (Callithrix jacchus), and validate an enzyme-linked immunosorbent assay (ELISA) technique previously unused in this species. Saliva samples were collected from marmosets housed in pairs in a UK laboratory. The assay showed parallelism, precision, accuracy and sensitivity, meeting the criteria typically used to investigate the effectiveness of new analytical techniques. Use of Salimetrics® Oral Swabs considerably increased the amount of cortisol recovered in comparison with previous studies using cotton buds. However, while use of banana on the swabs can encourage chewing, it may influence results. Although increases in cortisol levels have traditionally been interpreted as an indicator of stress in primates, there are many factors that affect the hypothalamic-pituitary-adrenal axis, with some studies showing decreases in cortisol levels post-stressor. Following a likely stressful event (capture for weighing), we also found cortisol levels significantly decreased, possibly due to social buffering or ‘blunting’ of the HPA axis. Order of weighing also had an effect. The method therefore provided an effective non-invasive means of assessing acute changes in cortisol level that may be more useful than previous methods, improving our ability to study physiological aspects of welfare in primates. We discuss methodological considerations, as well as implications of using cortisol as a measure of stress.
  • Technical note: Validation of an automatic recording system to assess behavioural activity level in sheep (Ovis aries).

    McLennan, Krista M.; Skillings, Elizabeth, A.; Rebelo, Carlos J. B.; Corke, Murray J.; Pires Moreira, Maria A.; Morton, A. Jennifer; Constantino-Casas, Fernando; University of Cambridge; Universidade Federal Rural do Semi-Arido (Elsevier, 2015-06-01)
    The welfare of an individual can be assessed by monitoring behavioural changes, such as inactivity, that may indicate injury or disease. In this study we validated the Actiwatch Mini® activity monitor (AM) for automatic recording of behavioural activity levels of nine Texel ewes. The AM devices were attached to collars placed around the necks of the ewes. AM recordings were taken at 25 second intervals for 21 consecutive days and in addition, direct behavioural observations made on days 9 to 13. AM recordings were compared with direct behavioural observations to investigate whether different levels of behaviour activity could be distinguished by the AM. Six different behaviours were matched to the activity scores recorded by the AM which were low activity (lying ruminating, lying), medium activity (standing, standing ruminating, and grazing) and high activity behaviours (walking). There were differences in the activity scores for all three scores. However, higher levels of accuracy in distinguishing between activity levels were achieved when combining high and medium activity level behaviours. This method of capturing data provides a practical tool in studies assessing the impact of disease or injury. For example, assessing the effects of lameness on the activity level of sheep at pasture, without the presence of an observer influencing behaviour.
  • Hen Harrier Circus cyaneus nest sites on the Isle of Mull are associated with habitat mosaics and constrained by topography

    Geary, Matthew; Haworth, Paul F.; Fielding, Alan H.; University of Chester; Haworth Conservation Ltd. (Taylor & Francis, 2018-02-07)
    Capsule: Hen Harrier on the Isle of Mull, UK, are associated with habitat mosaics consisting of moorland, scrub and forestry but avoid grazed land, suggesting that forested habitats could be managed sympathetically for Hen Harrier in the future should the current UK population increase. Aims: To use distribution modelling to investigate nesting habitat associations using a long term dataset for Hen Harrier on Mull. Methods: We develop area-interaction models using a LASSO penalty to explore the distribution of 102 Hen Harrier nest sites in relation to habitat and topography. Our model is then successfully validated in tests using data for 70 nest sites from subsequent years. Results: Our model is effective in predicting suitable areas for Hen Harrier nest sites and indicates that Hen Harriers on Mull are found in habitat mosaics below 200 m asl. Hen Harrier nest intensity is positively associated with increasing proportions of moorland and scrub, open canopy forestry and closed canopy forestry. Nest intensity is negatively associated with increasing proportions of grazed land. Conclusion: Hen Harrier avoid grazed areas but are relatively tolerant of other habitat combinations. These findings are supported by previous observations of Hen Harrier habitat use and have implications for the recovery of some Hen Harrier SPA populations and future forest management. Open canopy forest and forest mosaics could potentially be incorporated into landscape-scale conservation plans for Hen Harriers using the population in Mull as an example.
  • Maria Ogilvie Gordon

    Burek, Cynthia V.; University of Chester (University of Edinburgh, 2018-03)
    This is a biographical entry for Maria Ogilvie Gordon
  • The Role of Local Societies in Early Modern Geotourism - A case study of the Chester Society of Natural Science and the Woolhope Naturalists' Field Club

    Burek, Cynthia V.; Hose, Thomas A.; University of Chester; University of Bristol (Geological Society of London, 2016-02-01)
    Local voluntary natural science societies played an important role in the development of early modern geotourism. This chapter explores the development of field, especially geological, excursions and their popularity in two local natural science societies – The Chester Society of Natural Science and the Woolhope Naturalists’ Field Club – from the 1850s to the 1950s. Both Q21 societies were established in the borderlands between England andWales and had a strong emphasis on local and regional scientific studies. They exemplify broader trends in public engagement in the natural sciences and associated fieldwork consequent upon the British socio-political environment. Further, they draw out comparisons between the attitudes of society to excursions and scientific fieldwork, as well as involvement by social status and gender.
  • Geodiversity Action Plans – A method to facilitate, structure, inform and record action for geodiversity.

    Burek, Cynthia V.; Dunlop, Lesley; Larwood, Jonathan G.; University of Chester; Northumbria University, Natural England (Elsevier, 2017-12-15)
    Geodiversity Action Plans are used widely within the United Kingdom to inform and record action for geodiversity and geoconservation. They encompass both site-based audit and conservation with a wider perspective on geodiversity resources available in an agreed area (such as geological sites, museum collections and building stones) with ambitions to present and communicate, influence policy and practice, and to secure resources in relation to geodiversity. Geodiversity Action Plans (GAPs) are used particularly at local and company level to focus and highlight the work needed to be carried out and a as key mechanism to facilitate and support the delivery of the overarching UK Geodiversity Action Plan (UKGAP). Importantly, GAPs cross cut interests and are multidisciplinary. Although they are mainly a UK tool for geoconservation the principles and approach are easily transferred and could be duplicated in other countries.
  • Archibald Geikie: His influence on and support for the roles of female geologists

    Burek, Cynthia V.; University of Chester (Geological Society of London, 2018)
    This chapter explores the interaction between Archibald Geikie and female geologists in their many different roles and within the social context of his life time (1835-1924). The roles adopted by female geologists altered around 1875 due to a change in the educational and legal background. Geikie’s attitude to female fieldwork and research publications changes through time too. His life is divided up into 5 different stages according to his influence. Case studies of both single and married women are explored looking at the influence and interaction they had with Archibald Geikie. They include Maria Ogilvie Gordon, Catherine Raisin, Annie Greenly, Gertrude Elles, Ethel Skeat and Ethel Wood. Was one female role more acceptable to him than others? Geikie seems to accept most of the roles they undertook and he supported them wherever he could.
  • Animal Social Network Theory Can Help Wildlife Conservation

    Snijders, Lysanne; Blumstein, Daniel; Franks, Daniel Wayne; Stanley, Christina; University of Chester; Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin; Wageningen University & Research; University of California; University of York (Elsevier, 2017-06-22)
    Many animals preferentially associate with certain other individuals. This social structuring can influence how populations respond to changes to their environment, thus making network analysis a promising technique for understanding, predicting and potentially manipulating population dynamics. Various network statistics can correlate with individual fitness components and key population-level processes, yet the logical role and formal application of animal social network theory for conservation and management have not been well articulated. We outline how understanding of direct and indirect relationships between animals can be profitably applied by wildlife managers and conservationists. By doing so, we aim to stimulate the development and implementation of practical tools for wildlife conservation and management and to inspire novel behavioral research in this field.
  • Social stability in semiferal ponies: networks show interannual stability alongside seasonal flexibility

    Stanley, Christina R.; Mettke-Hofmann, Claudia; Hager, Reinmar; Shultz, Susanne; University of Chester; University of Manchester; Liverpool John Moores University (Elsevier, 2017-06-23)
    Long-term relationships that underlie many stable mammalian groups often occur between philopatric kin. Although stable groups of nonrelatives appear to be less common, there is increasing evidence that social bonds between nonkin may confer sufficient intrinsic fitness benefits for these groups to persist. Here we evaluate whether social stability occurs in a bisexually dispersing species where social bonds have been shown to have reproductive benefits: the feral horse, Equus caballus. First, we quantified female social stability by applying a three-level framework to a 3-year data set of associations in semiferal ponies; this tested for stability at the individual, dyadic and subpopulation levels. Despite the relative weakness of these female bonds, we found significant social stability across all levels, as shown by stable association preferences, social networks and individual network positions. Second, we investigated how seasonality impacts on social bond strength and grouping patterns. We found seasonal fluctuations in female gregariousness, with a peak during the mating season. We therefore propose that significant social stability in female horses is coupled with a degree of flexibility that allows for effects of ecological fluctuations. Although social network analysis is widely used in behavioural ecological research, this is one of only a handful of studies to assess the temporal dynamics of networks over a significant timescale. Temporal stability in female relationships suggests that equid social structures are multifaceted: although bonds between stallions and mares are clearly strong, long-term relationships between mares underpin the social network structure. We suggest this framework could be used to assess social stability in other group-living species in order to improve our understanding of the nature of social bonds.

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