1,113 research outputs found

    Assembling a species–area curve through colonization, speciation and human‐mediated introduction

    Full text link
    AimThe fundamental biogeographical processes of colonization, speciation and extinction shape island biotas in space–time. On oceanic islands, area and isolation affect these processes and resulting biodiversity patterns. In the Anthropocene, a new human‐mediated colonization dynamic is altering insular ecosystems world‐wide. Here, we test predictions about the roles of archipelago area and isolation in structuring ant diversity patterns through effects on both natural and anthropogenic biogeographical processes.LocationTropical Pacific islands.MethodsWe compiled a comprehensive data set of ant faunal compositions across tropical Pacific archipelagos. Using regression analysis we evaluated the bivariate and interactive effects of area and isolation on the number of colonizing lineages, native species, endemic species, exotic species and total richness in the archipelago.ResultsThere is a strong species–area effect and a much more modest isolation effect on total ant species richness across the Pacific archipelagos. The number of colonizing lineages of each archipelago is strongly driven by the isolation of the archipelago. Endemic species are present in large archipelagos of low and intermediate isolation. The most remote archipelagos are nearly devoid of endemic lineages and their ant faunas are largely composed of Pacific Tramp species and exotics brought from outside the Pacific region.Main conclusionsThe prominent species–area curve in Pacific ants emerged over time through multiple processes. The colonization of lineages is determined primarily by isolation, with few or no lineages reaching remote archipelagos. Cladogenesis mediates the isolation effect and increases the area effect through the differential radiation of lineages in large archipelagos. In the Anthropocene, the assembly of the species–area relationship has accelerated dramatically through human‐mediated colonization. Overall, our results support a view that species–area curves reflect regulating limits on species richness that scale with area, but that multiple biogeographical processes can occur to achieve these limits.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136723/1/jbi12884.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136723/2/jbi12884_am.pd

    A New Ant Colony Algorithm Using the Heterarchical Concept Aimed at Optimization of Multiminima Continuous Functions

    Full text link
    Ant colony algorithms are a class of metaheuristics which are inspired from the behaviour of real ants. The original idea consisted in simulating the stigmergic communication, therefore these algorithms are considered as a form of adaptive memory programming. A new formalization is proposed for the design of ant colony algorithms, introducing the biological notions of heterarchy and communication channels. We are interested in the way ant colonies handle the information. According to these issues, an heterarchical algorithm called "Continuous Interacting Ant Colony" (CIAC) is designed for the optimization of multiminima continuous functions. CIAC uses two communication channels showing the properties of stigmergic and direct communications. CIAC presents interesting emergent properties as it was shown through some analytical test functions

    Quick and Dirty: Some Psychosocial Costs Associated with the Dark Triad in Three Countries

    Get PDF
    The current study provides the first examination of the relationship between life history indicators and the Dark Triad traits in an international sample drawn from the U.S. (n = 264), Singapore (n = 185), and Poland (n = 177). In all three samples, the Dark Triad traits were associated with psychosocial costs, although there were more links in the Singaporean and Polish samples than in the American sample. In the U.S., the quality of one’s romantic relationships and psychopathy were negatively correlated. Narcissism was higher in the Polish and American samples than in the Singaporean sample. Men scored higher than women did regardless of location and the sex difference in the individual differences in life histories was mediated by the Dark Triad composite. Results suggest the Dark Triad are related to a volatile socioecology composed of psychosocial costs in the familial, romantic, and platonic relationships

    Evolutionary Roots of Property Rights; The Natural and Cultural Nature of Human Cooperation

    Get PDF
    Debates about the role of natural and cultural selection in the development of prosocial, antisocial and socially neutral mechanisms and behavior raise questions that touch property rights, cooperation, and conflict. For example, some researchers suggest that cooperation and prosociality evolved by natural selection (Hamilton 1964, Trivers 1971, Axelrod and Hamilton 1981, De Waal 2013, 2014), while others claim that natural selection is insufficient for the evolution of cooperation, which required in addition cultural selection (Sterelny 2013, Bowles and Gintis 2003, Seabright 2013, Norenzayan 2013). Some scholars focus on the complexity and hierarchical nature of the evolution of cooperation as involving different tools associated with lower and the higher levels of competition (Nowak 2006, Okasha 2006); others suggest that humans genetically inherited heuristics that favor prosocial behavior such as generosity, forgiveness or altruistic punishment (Ridley 1996, Bowles and Gintis 2004, Rolls 2005). We argue these mechanisms are not genetically inherited; rather, they are features inherited through cultural selection. To support this view we invoke inclusive fitness theory, which states that individuals tend to maximize their inclusive fitness, rather than maximizing group fitness. We further reject the older notion of natural group selection - as well as more recent versions (West, Mouden, Gardner 2011) – which hold that natural selection favors cooperators within a group (Wynne-Edwards 1962). For Wynne-Edwards, group selection leads to group adaptations; the survival of individuals therefore depends on the survival of the group and a sharing of resources. Individuals who do not cooperate, who are selfish, face extinction due to rapid and over-exploitation of resources

    Non‐consumptive effects of predation: does perceived risk strengthen the genetic integration of behaviour and morphology in stickleback?

    Get PDF
    Predators can shape genetic correlations in prey by altering prey perception of risk. We manipulated perceived risk to test whether such non‐consumptive effects tightened behavioural trait correlations in wild‐caught stickleback from high‐ compared to low‐risk environments due to genetic variation in plasticity. We expected tighter genetic correlations within perceived risk treatments than across them, and tighter genetic correlations in high‐risk than in low‐risk treatments. We identified genetic variation in plasticity, with genetic correlations between boldness, sociality, and antipredator morphology, as expected, being tighter within treatments than across them, for both of two populations. By contrast, genetic correlations did not tighten with exposure to risk. Tighter phenotypic correlations in wild stickleback may thus arise because predators induce correlational selection on environmental components of these traits, or because predators tighten residual correlations by causing environmental heterogeneity that is controlled in the laboratory. Our study places phenotypic integration firmly into an ecological context

    Towards a collaborative, global infrastructure for biodiversity assessment

    Get PDF
    Biodiversity data are rapidly becoming available over the Internet in common formats that promote sharing and exchange. Currently, these data are somewhat problematic, primarily with regard to geographic and taxonomic accuracy, for use in ecological research, natural resources management and conservation decision-making. However, web-based georeferencing tools that utilize best practices and gazetteer databases can be employed to improve geographic data. Taxonomic data quality can be improved through web-enabled valid taxon names databases and services, as well as more efficient mechanisms to return systematic research results and taxonomic misidentification rates back to the biodiversity community. Both of these are under construction. A separate but related challenge will be developing web-based visualization and analysis tools for tracking biodiversity change. Our aim was to discuss how such tools, combined with data of enhanced quality, will help transform today's portals to raw biodiversity data into nexuses of collaborative creation and sharing of biodiversity knowledge

    The NR4A subgroup: immediate early response genes with pleiotropic physiological roles

    Get PDF
    The nuclear hormone receptor (NR) superfamily includes the orphan NR4A subgroup, comprised of Nur77 (NR4A1), Nurr1 (NR4A2) and NOR-1 (NR4A3). These NRs are classified as early response genes, are induced by a diverse range of signals, including fatty acids, stress, growth factors, cytokines, peptide hormones, phorbol esters, neurotransmitters, and physical stimuli (for example magnetic fields, shear stress). The ability to sense and rapidly respond to changes in the cellular environment thus appears to be a hallmark of this subfamily. The members of the NR4A subgroup are well conserved in the DNA binding domain (~91-95%) and the C-terminal ligand-binding domain (~60%), but are divergent in the N-terminal AB region. These receptors bind as monomers, homodimers and heterodimers with RXRs (to mediate retinoid signaling) to different permutations of the canonical NR binding motif. The NR4A subgroup activates gene expression in a constitutive ligand-independent manner. NR4A-mediated trans-activation (LBD) involves unusually active N-terminal AF-1 domains that mediate coactivator recruitment. Moreover, the NR4A receptors encode atypical LBDs and AF-2 domains. For example, the LBDs contain no cavity due to bulky hydrophobic residue side chains, and lack the classical coactivator-binding cleft constituted by helices 3, 4 and 12. However, a hydrophobic patch exists between helices 11 and 12, that encodes a novel cofactor interface that modulates transcriptional activity. In line with the pleiotropic physiological stimuli that induce the NR4A subgroup, these orphan NRs have been implicated in cell cycle regulation (and apoptosis), neurological disease, steroidogenesis, inflammation, carcinogenesis and atherogenesis

    Class Position of Immigrant Workers in a Post-Industrial Economy: The Dutch Case

    Get PDF
    In this paper, the issue of changing labour-market opportunities and the position of members of minority groups in advanced service economies is addressed, focusing on the Dutch case. We distinguish between two social hierarchies, one of traditional ‘fordist’ occupations and one of post-fordist occupations. Compared to the native Dutch, all immigrant groups are over-represented at the bottom of the labour market, both in the fordist and in the postindustrial hierarchy. Increased immigrant labour-market participation in the 1990s was accompanied by a strong rise in the number of flexible labour contracts. Native Dutch also work more frequently on flexible labour contracts, but not to the same extent as immigrants. The lower occupational level of the Surinamese, Antilleans and other non-Western immigrants employed in post-industrial occupations can be attributed to their low educational level. This is not true, however, for Turks, Moroccans and other non-Western immigrants employed in fordist occupations. Their low occupational level can not be completely explained by their low educational level. The effects of changes in the economic structure differ for ethnic groups, depending on their past employment, their cultural capital and the institutional framework in which they have to operate

    The Designers Leap: Boundary Jumping to foster interdisciplinarity between Textile Design and Science

    Get PDF
    Creative thinking is an instinctive problem-solving process for designers however, designers alone cannot solve real-world problems. Collaboration between higher education and industry, and across design and science disciplines can create new paradigms of research to address societal and economic challenges. This paper argues from the perspective of fashion and textile designers, for design to be at the heart of the collaborative research process and advocates for co-design, speculative-design and scenario design to be considered as valid methodologies to foster interdisciplinarity. Perspectives on interdisciplinary partnerships across academic disciplines and with industry are typified by two very different reflections of collaborative projects between fashion designers, textile designers, scientists and industrial partners. The paper identifies commonalities and differences between scientists and designers, with particular relevance to textiles, in a bid to understand how they may collaborate more effectively in the context of interdisciplinary work, and the paper further identifies factors needed for establishing common enablers for engaging in co-design. This is an under-explored field and highlights the changing role of the designer, and as such is of value to researchers in textiles, fashion and product design
    • 

    corecore