Foraging in the tropics: relationships among species’ abundances,niche asymmetries and body condition in an urban avian assemblage

Two main theories attempt to explain species coexistence: the neutral theory considers all the species as equivalents so biodiversity is mainly regarded as a function of total available resources (i.e. niche expansion), while the niche theory stresses the relevance of differences in niche use between species (i.e. niche packing). The relative importance of these forces is under discussion and has been largely tested in natural ecosystems. However, few studies have addressed this issue in tropical-urban environments. In this work we studied niche overlap asymmetries among the most common urban resident birds, and the effect of habitat type on this pattern, in a subtropical location of South China (Nanning, Guangxi). We found differences in abundances and niche use among species and urban habitats (parks, streets and orchards). We also recorded strong asymmetries in niche use between species, which we divided into three categories: species with positive asymmetries, which showed highly specific niches and were able to exploit other species’ niches; species with neutral asymmetries, which showed high levels of niche overlap with the rest of species; and species with negative asymmetries, which showed low specificity in their niches and were unable to exploit other species’ niches. These differences in niche use correlated with differences in fat scores. Species from the first group showed higher fat scores than other two groups. Ultimately, niche asymmetries correlated with species’ body condition and mediated their differences in abundance, which supports the view that in this urban context niche theory is more appropriate than neutral theory.     

The Organizational Niche

Although the concept of niche has been extremely useful in sociological theory and research, some aspects of the concept have not been clearly developed. This article advances a theoretical reconstruction of the concept of niche, with special application to organizations. The proposed formal model unifies several active lines of sociological theory. It also extends the notion of the niche from the realm of behaviors to apply to the rules coding social identities and organizational forms. The reconstruction gives deeper insight into the niche of an organizational population as well as individual organizations. Finally, the model analyzes the (thus far) tacit assumption that niches are convex, examines the implications of convexity for commonly used measures of niche width, and provides a general sociological argument for the predominance of convex niches.     

Moving targets: determinants of nutritional preferences and habitat use in an urban ant community

Urban environments are often associated with reduced biodiversity, presumably because they are typically more fragmented, warmer, and drier than nearby non-urban environments. However, urban landscapes offer significant complexity that have allowed some taxonomic groups to flourish. Understanding how urban-exploiting animals navigate this spatiotemporal heterogeneity is important given the continued global urban land expansion. Here, we examined the factors influencing resource-use in an urban community of ants, which represent a widespread and important taxon in urban ecosystems. In particular, we sought to integrate ants’ nutritional, thermal, and spatial niches to better understand how urban animals successfully access critical resources throughout their active season. Meteorological season (spring, summer, and fall) and/or species (n?=?9) influenced ants’ preferences for nutrition (ratio of ingested protein-to-carbohydrate ratio), as well as the temperature, type (impervious vs. non-impervious), and shade status (shaded vs. non-shaded) of surfaces used during activity. Our data also indicate links among habitat variables, as well as between nutritional preferences and habitat use. Together, our results suggest that species and seasonality influence ecological (combined nutritional, thermal, and spatial) niches in an urban community. We encourage future work in urban ecosystems that continues to integrate more features of the ecological niche, and to examine the outcomes of variation in niches (e.g., non-overlapping niches may explain both the persistence of some native animals and the success of invaders).     

Defectors’ niches: prisoner's dilemma game on disordered networks

Effects of disordered networks on evolution of cooperation are studied based on the prisoner's dilemma game on a random regular relational graph. As a parameter q (0 ≤ q ≤ 1) that controls a degree of randomness of the network varies from zero to unity, the initial two-dimensional square lattice network becomes more relationally randomized while regularity of the network is kept. It is shown that random connections that make possible cooperator jump into defectors’ clusters ironically trigger the formation of defectors’ niches, in which defectors impose upon cooperators and do not have incentive to change their strategy.     

The making and transnationalization of an ethnic niche: Vietnamese manicurists

The article addresses how Vietnamese immigrant women developed an urban employment niche in the beauty industry, in manicuring. They are shown to have done so by creating a market for professional nail care, through the transformation of nailwork into what might be called McNails, entailing inexpensive, walk-in, impersonal service, in stand-alone salons, nationwide, and by making manicures and pedicures de riguer across class and racial strata. Vietnamese are shown to have simultaneously gained access to institutional means to surmount professional manicure credentializing barriers, and to have developed formal and informal ethnic networks that fueled their growing monopolization of jobs in the sector, to the exclusion of non-Vietnamese. The article also elucidates conditions contributing to the Vietnamese build-up and transformation of the niche, to the nation-wide formation of the niche and, most recently, to the transnationalization of the niche. It also extrapolates from the Vietnamese manicure experience propositions concerning the development, expansion, maintenance, and transnationalization of immigrant-formed labor market niches.     

“The Ecology of Decline and Revitalization in PSA”

Professional organizations all exist in resource niches and, over time, confront varying degrees of density and, hence, competition with other organizations. The initial founding and growth, the precipitous decline, and the subsequent revitalization of the Pacific Sociological Association over the last six decades can be analyzed from an ecological perspective, suggesting strategies for the further survival of PSA in an every more dense resource niche.     

Social Capital Investment and Immigrant Economic Trajectories: A Case Study of Punjabi American Taxi Drivers in New York City

Although the scholarship on social capital and immigrant economic incorporation has sufficiently documented how immigrants mobilize social capital in their search for employment which often leads to the formation of immigrant niches, how social capital is processed after immigrants acquire employment and its significance for the preservation of immigrant employment niches is less well explored. This paper addresses this gap in the literature with a case study of immigrant Punjabi taxi drivers in the New York metropolitan area. In particular, this study shows how a group of immigrant Punjabi taxi drivers mobilized social capital via embeddedness in co‐ethnic social networks and improved their working conditions – a process that must be considered in explanations of the Punjabi niche in the taxi industry for more than two decades. The study has implications for the relationship between social capital and the structure of the workplace or industry where immigrants are incorporated and its subsequent impact on immigrant economic trajectories. Further, this study contributes to the debate on the usefulness of ethnic communities for the adaptation of immigrant groups. Additionally, this research is relevant to the scholarship on the economic adaptation of South Asian (a subset of Asian Americans) immigrants, an understudied immigrant group in the United States.     

Professions and the Social Order: Some Lessons from Burkina Faso?

The study of professions has been dominated by Anglo‐American models, with their focus on a small group of legally licensed occupations. The field has recently shifted, mainly through studies of European experience, to a wider examination of the social management of expert workers. Very little has been written about developments in Africa and their implications for the way in which we might think about professions. This paper presents a case study of the role and practices of the medical profession in Burkina Faso, which has a relatively open market for the supply of healing services and limited regulation of the suppliers, whether physicians or traditional practitioners. The study returns to classic questions about the extent to which practice is shaped by the nature of occupational niches within the division of labor or to the development of a distinctive moral character among the workers within that niche.     

THE ROLE OF LEADERSHIP AND STRATEGY IN NAVIGATING POLITICAL INCORPORATION: Defining a Niche for Human Relations in Orange County, California, 1971–2000

Political incorporation represents an important and complex trajectory for social movements. Whether that trajectory leads to favorable substantive outcomes or merely to formalistic representation within the polity depends in part on the strategic decisions made by leaders. We have few frameworks, however, for understanding their role in navigating incorporation. This research presents a "niche definition" framework emphasizing strategic differentiation and articulation across political actors in distinct institutional locations sharing common goals. It focuses attention on leaders' efforts to identify and exploit unique resources and leverage made available through incorporation. Overall, the framework emphasizes the potential for collective strategy and cooperative interorganizational dynamics, thereby expanding possibilities for favorable outcomes of political incorporation. The framework is illustrated through a case study of the Orange County (California) Human Relations Commission from its creation in 1971 to 2001. I trace the long-term challenges and consequences of incorporation through leaders' definition of successive niches.     

Tenures in Transition,Tenures in Conflict: Examples from the Zimbabwe Social Forest1

The landscapes of rural communities are commonly divided into areas in which distinctive resource uses are practiced and for which there exist particular types of property rights. Such tenure niches for different resources may overlap where those resources themselves occupy the same space (e.g., land and trees). Further, competing legal and utilization systems (e.g., national and local) may place the same resource in different incompatible tenure niches. Conflict may involve overlapping tenure niches. Co-management by conflicting right-holders may offer a solution.     

Triadic configurations in limited choice sociometric networks: Empirical and theoretical results

Previous research demonstrated that information contained in triad censuses from heterogeneous collections of social networks occupies a high dimensional space. Regions of this space, and locations of triad censuses within it, are largely defined by lower order network properties: network density and dyad distributions [Faust, K., 2006. Comparing social networks: size, density, and local structure. Metodološki Zvezki (Advances in Methodology and Statistics) 3 (2), 185–216; Faust, K., 2007. Very local structure in social networks. Sociological Methodology 37, 209–256]. The current paper extends comparative work on triad censuses by addressing three related issues. First, it determines and interprets the space occupied by triad censuses for 128 friendship networks gathered using a limited choice sociometric protocol. Second, it constructs a theoretical space for triad censuses expected given lower order graph properties and examines the dimensionality and shape of this space. Third, it brings together these lines of investigation to determine where the empirical triad censuses reside within the theoretical space. Results show that the empirical triad censuses are almost perfectly represented in one dimension (explaining 99% of the data) and that network density explains over 96% of the variance in locations on this dimension. In contrast, the theoretical space for triad censuses is at least four-dimensional, with distinctive regions defined by network density and dyad distributions. Within this theoretical space, the empirical triad censuses occupy a restricted region that closely tracks triad censuses expected given network density. Results differ markedly from prior findings that the space occupied by triad censuses from heterogeneous social networks is of high dimensionality. Results also reinforce observations about constraints that network size and density place on graph level indices.     

Relational rurals: Some thoughts on relating things and theory in rural studies

This paper considers how shifts within the social sciences towards conceptualising spatiality in relational terms have unfolded in rural studies in particular ways over the past decade or so. A period in which networks, connections, flows and mobility have all established themselves as compelling conceptual frames for research, the rural has increasingly been recast in relational terms as a multi-authored and multi-faceted space, constituted through local-global interconnections and their place specific, sometimes contested, manifestations. In this way, the multiple meanings of the rural continues to be a focus of critical concern, as are the implications ‘of’ and ‘in’ rural spaces for some of the major issues currently being faced by governments and citizens around the world; including climate change and food security. Apprehending the complexity of the rural in these terms, we argue, requires not only thinking space relationally, but at the same time being epistemologically relational or theoretically pluralist. That is, recognising the co-constituent production of rural space through material and discursive phenomenon, processes and practices, and thus the value of existing theoretical resources (social constructionism, political and economic materialism) in relation with the critical and rigorous appraisal of ‘new’ concepts and ideas to better comprehend rural space in its multidimensional complexity and particularity. To this end, we identify Cindi Katz's notion of ‘countertopography’ as a promising conceptual and methodological addition to the rural scholar's toolkit insofar as it attends to a politics of location and differentation in relation to global processes. We conclude our discussion by sketching out possible objects of countertopographical analysis for understanding ongoing processes of change in rural space(s).     

THE PRESENTATION OF ETHNIC AUTHENTICITY:

Ethnic entrepreneurs in American society often carve out an economic niche by means of business enterprises and cultural events that are open to the general public and showcase ethnic culture. These locations depend upon a display of the ethnic culture that is simultneously seen as "authentic" and within the bounds of cultural expectations ("Americaized"). In a society that values toleration and cross-cultural contacts, many consumers desire a unique, yet comfortable experience, given their own cultural preferences. We focus on the presentation of ethnic food in four Chinese restarants in a small southern city. Ethnic tradition continues but in the context of a continuous process of adaptation. Authenticity is not an objective criterion but is socially constructed and linked to expectations. We contrast two broad classes of Chinese restarants—consumption-oriented and connoisseur-oriented—to describe strategies by which restaurateurs fit Chinese food into market niches. We conclude by suggesting some directions for the study of public ethnic culture.     

Non-collegial simple games and the nowhere denseness of the set of preference profiles having a core

In recent papers, somewhat conflicting results on the generic emptiness of the core have been proven. Rubinstein (1979) has shown that the core is generically empty in the Kannai topology even without a restriction on the dimensionality of the alternative space. Schofield (1980) finds the core generically empty in the Whitney-C topology, but requires a dimensionality condition. This note explores the apparent conflict by proving a generalization of Rubinstein's result for the Whitney-C ⁰ topology, and showing that the result does not extend to the Whitney-C ¹ topology without a dimensionality condition.I would like to thank Kim Border and Richard McKelvey for their helpful discussion and comments. This research was supported in part by the National Science Foundation under Grant no. SES 78-2478781     

The core of social choice problems with monotone preferences and a feasibility constraint

We consider collective choice with agents possessing strictly monotone, strictly convex and continuous preferences over a compact and convex constraint set contained in ₊^k . If it is non-empty the core will lie on the efficient boundary of the constraint set and any policy not in the core is beaten by some policy on the efficient boundary. It is possible to translate the collective choice problem on this efficient boundary to another social choice problem on a compact and convex subset of ₊^c (c<k) with strictly convex and continuous preferences. In this setting the dimensionality results in Banks (1995) and Saari (1997) apply to the dimensionality of the boundary of the constraint set (which is lower than the dimensionality of the choice space by at least one). If the constraint set is not convex then the translated lower dimensional problem does not necessarily involve strict convexity of preferences but the dimensionality of the problem is still lower. Broadly, the results show that the homogeneity afforded by strict monotonicity of preferences and a compact constraint set makes generic core emptyness slightly less common. One example of the results is that if preferences are strictly monotone and convex on ² then choice on a compact and convex constraint exhibits a version of the median voter theorem.I thank Donald Saari for helpful comments on an earlier version of this paper.     

The Occupational Prestige Structure: a Multidimensional Scaling Approach

Occupational prestige scores are one of the more frequently used variables in sociological research. However, the methods which have been employed in the past to obtain such scores are based on the implicit assumption that the occupational prestige structure is unidimensional. The technique of smallest space analysis, which makes no assumption about dimensionality, suggests that this previous assumption has produced a somewhat inaccurate picture of the occupational prestige structure.     

Power in the production of spaces transformed by rural tourism

The article critiques Halfacree's conceptualisation of rural space for masking the workings of power within ‘black boxes’ such as structural coherence and trial by space. One consequence is that rural change's social activities and also their social and personal consequences are cloaked, thereby rendering the localised fault lines of rurality analytically out of reach. Halfacree's conceptualisation is developed further by attaching a conceptual extension comprising three hubs: an immaterial hub, a material hub, and a personal hub. This is done as an attempt to give Halfacree's tool for deconstructing the social production of rural space analytical sensitivity to the actors engaged in the processes implied by social production. In order to demonstrate the analytical potential of the extended Halfacree approach, the conceptual model is applied to a case study: data from two communities undergoing rapid change, as they shifted from being dominated by primary industry to becoming tourism destinations.     

What constitutes great IDEA? An examination of corporate diversity communication on facebook and external and internal stakeholder reactions

This study conducted a quantitative content analysis to examine corporate Inclusivity, Diversity, Equity, and Accessibility (IDEA) communication (n = 1216) from 48 corporations on Facebook through the lens of dimensionality, stakeholders, drivers (legitimation), and level of investment. Findings indicated that most of the IDEA communication on Facebook focused on gender and racial/ethnicity diversity, employee, and community stakeholders. The IDEA communication was almost equally value- and performance-driven and reflected external promotion level of investment. External stakeholders engaged more with performance-driven and external promotion IDEA communication. The volume of IDEA posts reflected corporate internal diversity practice and was positively related with Glassdoor ratings of the corporation by African American, Middle Eastern, and LGBTQ+ employees.     

Urban ecosystems: the human dimension

This paper develops a human ecological perspective on cities and urban regions. It describes the role of cities in the expanding human ecological niche and its implications for sustainable urban development. I have used a new technique, ecological footprint analysis, to convert the material and energy flows required to sustain the human population and industrial metabolism of the city into a landecosystem area equivalent. This approach emphasizes that, although urbanization has become the dominant human settlement pattern, cities themselves constitute only a small part of the total ecological space appropriated by their human inhabitants. In short, the ecological locations of human settlements no longer coincide with their geographic locations. Every city and urban region depends for its existence and growth on a globally diffuse productive hinterland up to 200 times the size of the city itself. Cities are therefore increasingly vulnerable to global ecological change and geopolitical instability. Given the deteriorating state of the ecosphere, policies to decrease the ecological footprint of cities while increasing regional self-reliance may enhance urban sustainability.     

The Social Ecology of Marriage and Other Intimate Unions

This article provides an interdisciplinary framework for studying marital and other intimate relationships. Three levels of analysis are distinguished: (a) the society, characterized in terms of both macrosocietal forces and the ecological niches within which particular spouses and couples function; (b) the individual spouses, including their psychosocial and physical attributes, as well as the attitudes and beliefs they have about each other and their relationship; and (c) the marriage relationship, viewed as a behavioral system embedded within a larger network of close relationships. The discussion focuses primarily on the interplay between the spouses and their marriage, emphasizing the importance of distinguishing, both analytically and operationally, the individual from the dyadic (or group) levels of analysis. It is also argued that in order to appreciate how marriages work, social scientists must understand not only how these 2 levels of analysis interpenetrate each other but also how macrosocietal forces and the ecological niches within which couples live impinge on partners and their marital relationship.