649 research outputs found

    Strategy and Organisational Cybersecurity: A Knowledge-Problem Perspective

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    Purpose: The purpose of this paper is to frame organisational cybersecurity through a strategic lens, as a function of an interplay of pragmatism, inference, holism and adaptation. The authors address the hostile epistemic climate for intellectual capital management presented by the dynamics of cybersecurity as a phenomenon. The drivers of this hostility are identified and their implications for research and practice are discussed. Design/methodology/approach: The philosophical foundations of cybersecurity in its relation with strategy, knowledge and intellectual capital are explored through a review of the literature as a mechanism to contribute to the emerging theoretical underpinnings of the cybersecurity domain. Findings: This conceptual paper argues that a knowledge-based perspective can serve as the necessary platform for a phenomenon-based view of organisational cybersecurity, given its multi-disciplinary nature. Research limitations/implications: By recognising the knowledge-related vectors, mechanisms and tendencies at play, a novel perspective on the topic can be developed: cybersecurity as a “knowledge problem”. In order to facilitate such a perspective, the paper proposes an emergent epistemology, rooted in systems thinking and pragmatism. Practical implications: In practice, the knowledge-problem narrative can underpin the development of new organisational support constructs and systems. These can address the distinctiveness of the strategic challenges that cybersecurity poses for the growing operational reliance on intellectual capital. Originality/value: The research narrative presents a novel knowledge-based analysis of organisational cybersecurity, with significant implications for both interdisciplinary research in the field, and practice

    A niche perspective on the range expansion of symbionts

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    Range expansion results from complex eco-evolutionary processes where range dynamics and niche shifts interact in a novel physical space and/or environment, with scale playing a major role. Obligate symbionts (i.e. organisms permanently living on hosts) differ from free-living organisms in that they depend on strong biotic interactions with their hosts which alter their niche and spatial dynamics. A symbiotic lifestyle modifies organism–environment relationships across levels of organisation, from individuals to geographical ranges. These changes influence how symbionts experience colonisation and, by extension, range expansion. Here, we investigate the potential implications of a symbiotic lifestyle on range expansion capacity. We present a unified conceptual overview on range expansion of symbionts that integrates concepts grounded in niche and metapopulation theories. Overall, we explain how niche-driven and dispersal-driven processes govern symbiont range dynamics through their interaction across scales, from host switching to geographical range shifts. First, we describe a background framework for range dynamics based on metapopulation concepts applied to symbiont organisation levels. Then, we integrate metapopulation processes operating in the physical space with niche dynamics grounded in the environmental arena. For this purpose, we provide a definition of the biotope (i.e. living place) specific to symbionts as a hinge concept to link the physical and environmental spaces, wherein the biotope unit is a metapopulation patch (either a host individual or a land fragment). Further, we highlight the dual nature of the symbionts' niche, which is characterised by both host traits and the external environment, and define proper conceptual variants to provide a meaningful unification of niche, biotope and symbiont organisation levels. We also explore variation across systems in the relative relevance of both external environment and host traits to the symbiont's niche and their potential implications on range expansion. We describe in detail the potential mechanisms by which hosts, through their function as biotopes, could influence how some symbionts expand their range – depending on the life history and traits of both associates. From the spatial point of view, hosts can extend symbiont dispersal range via host-mediated dispersal, although the requirement for among-host dispersal can challenge symbiont range expansion. From the niche point of view, homeostatic properties of host bodies may allow symbiont populations to become insensitive to off-host environmental gradients during host-mediated dispersal. These two potential benefits of the symbiont–host interaction can enhance symbiont range expansion capacity. On the other hand, the central role of hosts governing the symbiont niche makes symbionts strongly dependent on the availability of suitable hosts. Thus, environmental, dispersal and biotic barriers faced by suitable hosts apply also to the symbiont, unless eventual opportunities for host switching allow the symbiont to expand its repertoire of suitable hosts (thus expanding its fundamental niche). Finally, symbionts can also improve their range expansion capacity through their impacts on hosts, via protecting their affiliated hosts from environmental harshness through biotic facilitation.info:eu-repo/semantics/publishedVersio

    Ecological Niches, Species Distributions, And Biogeographic Processes In Rodents On Neotropical Sky Islands

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    This dissertation focused on the methodological and theoretical improvement of correlative ecological niche models (ENMs) to better understand the processes governing species distributions and associated evolutionary divergence in rodents inhabiting mesic conditions in the Neotropics. Focusing on a widespread rodent from northern South America (Heteromys anomalus), in the first chapter I proposed and tested a methodological approach to surmount the challenge of incorporating environmental information from the margins of species geographic ranges into ENMs. In so doing, I argue how populations that exist on the borders of species\u27 local ranges (spatial margins) can lead to exaggerated estimates of their niches and potential geographic distributions due to issues of variable choice and resolution. In the second chapter, I demonstrated how the approach developed in Chapter 1 improved the ability of ENMs to detect an obvious environmental barrier fostering isolation and potential divergence between continental and peninsular populations in three rodent lineages in northern South America: Proechimys guairae, Rhipidomys venezuelae, and the Heteromys anomalus/H. oasicus species pair. In the third chapter, I integrated ENMs with molecular data to test the effect of the climatic oscillations of the late Quaternary Period in two species of rodents restricted to the sky islands of Costa Rica and western Panama: Reithrodontomys creper and Nephelomys devius. Overall, results revealed how, despite sharing similar distribution patterns, niche differences in these species resulted in idiosyncratic responses to past climate change that match currently observed patterns of genetic diversity. Finally, in the fourth chapter, I developed a perspective of the ecological niche concept that takes into account the responsiveness of phenotypes and the variability of ecological strategies that a species can perform. Integrating these aspects into niche theory leads to a more holistic perspective that reduces conflict between niche definitions, dissolves existing paradoxes, and has multiple implications for the study of niches, their evolution, and their effect on lineage divergence. Overall, this dissertation contributes to the conceptual and methodological development of correlative approaches for modeling species Grinnellian niches and their associated potential geographic distributions; the understanding of how these relate to the evolutionary history of Neotropical montane taxa with regards to past climate change; and finally, to a more holistic perspective of the niche concept that has multiple implications for the study of niches in general, as well as our understanding of how they evolve and affect lineage divergence

    Evolution from the ground up with Amee – From basic concepts to explorative modeling

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    Evolutionary theory has been the foundation of biological research for about a century now, yet over the past few decades, new discoveries and theoretical advances have rapidly transformed our understanding of the evolutionary process. Foremost among them are evolutionary developmental biology, epigenetic inheritance, and various forms of evolu- tionarily relevant phenotypic plasticity, as well as cultural evolution, which ultimately led to the conceptualization of an extended evolutionary synthesis. Starting from abstract principles rooted in complexity theory, this thesis aims to provide a unified conceptual understanding of any kind of evolution, biological or otherwise. This is used in the second part to develop Amee, an agent-based model that unifies development, niche construction, and phenotypic plasticity with natural selection based on a simulated ecology. Amee is implemented in Utopia, which allows performant, integrated implementation and simulation of arbitrary agent-based models. A phenomenological overview over Amee’s capabilities is provided, ranging from the evolution of ecospecies down to the evolution of metabolic networks and up to beyond-species-level biological organization, all of which emerges autonomously from the basic dynamics. The interaction of development, plasticity, and niche construction has been investigated, and it has been shown that while expected natural phenomena can, in principle, arise, the accessible simulation time and system size are too small to produce natural evo-devo phenomena and –structures. Amee thus can be used to simulate the evolution of a wide variety of processes

    The role of visual adaptation in cichlid fish speciation

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    D. Shane Wright (1) , Ole Seehausen (2), Ton G.G. Groothuis (1), Martine E. Maan (1) (1) University of Groningen; GELIFES; EGDB(2) Department of Fish Ecology & Evolution, EAWAG Centre for Ecology, Evolution and Biogeochemistry, Kastanienbaum AND Institute of Ecology and Evolution, Aquatic Ecology, University of Bern.In less than 15,000 years, Lake Victoria cichlid fishes have radiated into as many as 500 different species. Ecological and sexual sel ection are thought to contribute to this ongoing speciation process, but genetic differentiation remains low. However, recent work in visual pigment genes, opsins, has shown more diversity. Unlike neighboring Lakes Malawi and Tanganyika, Lake Victoria is highly turbid, resulting in a long wavelength shift in the light spectrum with increasing depth, providing an environmental gradient for exploring divergent coevolution in sensory systems and colour signals via sensory drive. Pundamilia pundamila and Pundamilia nyererei are two sympatric species found at rocky islands across southern portions of Lake Victoria, differing in male colouration and the depth they reside. Previous work has shown species differentiation in colour discrimination, corresponding to divergent female preferences for conspecific male colouration. A mechanistic link between colour vision and preference would provide a rapid route to reproductive isolation between divergently adapting populations. This link is tested by experimental manip ulation of colour vision - raising both species and their hybrids under light conditions mimicking shallow and deep habitats. We quantify the expression of retinal opsins and test behaviours important for speciation: mate choice, habitat preference, and fo raging performance

    Baldwin effects in early stone tools

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    A sizeable dataset comprising millions of lithic artifacts sampling over two millionyears of early paleolithic tool technology from Africa and Eurasia is now available.The widespread presupposition of an exclusively cultural, that is, socially learned,nature of early stone tools from at least Acheulean times onwards has been chal-lenged by researchers who hypothesize that these tools, a crucial element of earlyhominin survival strategies, may partly have been under genetic control, next to theeffects of various other determinants. The discussion this hypothesis has sparked offin the present journal is here explored somewhat further, focusing on the BaldwinA sizeable dataset comprising millions of lithic artifacts sampling over two millionyears of early paleolithic tool technology from Africa and Eurasia is now available.The widespread presupposition of an exclusively cultural, that is, socially learned,nature of early stone tools from at least Acheulean times onwards has been chal-lenged by researchers who hypothesize that these tools, a crucial element of earlyhominin survival strategies, may partly have been under genetic control, next to theeffects of various other determinants. The discussion this hypothesis has sparked offin the present journal is here explored somewhat further, focusing on the Baldwineffect.A sizeable dataset comprising millions of lithic artifacts sampling over two millionyears of early paleolithic tool technology from Africa and Eurasia is now available.The widespread presupposition of an exclusively cultural, that is, socially learned,nature of early stone tools from at least Acheulean times onwards has been chal-lenged by researchers who hypothesize that these tools, a crucial element of earlyhominin survival strategies, may partly have been under genetic control, next to theeffects of various other determinants. The discussion this hypothesis has sparked offin the present journal is here explored somewhat further, focusing on the Baldwineffect.A sizeable dataset comprising millions of lithic artefacts sampling overr two million years of early palaeolithic tool technology from Africa and Eurasia is now available. The widespread presupposition of an excluA sizeable dataset comprising millions of lithic artefacts sampling overr two million years of early palaeolithic tool technology from Africa and Eurasia is now available. The widespread presupposition of an exclusively cultural, i.e. sA sizeable dataset comprising millions of lithic artefacts sampling overr two million years of early palaeolithic tool technology from Africa and Eurasia is now available. The widespread presupposition of an exclusively cultural, i.e. socially learned, nature of early stone tools from at least Acheulean times onwards has been challenged by researchers who hypothesize that these tools, a crucial element of early hominin survival strategies, may partly have been under genetic control, next to the effects of various other determinants. The discussion this hypothesis has sparked off in the present journal is here explored somewhat further, focussing on the Baldwin Effect. ocially learned, nature of early stone tools from at least Acheulean times onwards has been challenged by researchers who hypothesize that these tools, a crucial element of early hominin survival strategies, may partly have been under genetic control, next to the effects of various other determinants. The discussion this hypothesis has sparked off in the present journal is here explored somewhat further, focussing on the Baldwin Effect. sively cultural, i.e. socially learned, nature of early stone tools from at least Acheulean times onwards has been challenged by researchers who hypothesize that these tools, a crucial element of early hominin survival strategies, may partly have been under genetic control, next to the effects of various other determinants. The discussion this hypothesis has sparked off in the present journal is here explored somewhat further, focussing on the Baldwin Effect. effect.Human Origin

    Exploring mechanisms that shape Siphonaptera composition and distribution patterns on small mammals across South Africa

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    Thesis (PhD)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Fleas (Siphonaptera) are obligate ectoparasites of mammals and birds. Due to their economic importance as disease vectors, most contemporary studies on macroparasites now also consider the spatial variation of parasite communities and the underlying mechanisms involved in shaping current distribution patterns. Fleas differ in life history traits, such as the level of host specificity and microhabitat preferences, which can result in differential evolutionary responses to similar abiotic events. The main objectives of this study are to investigate: (1) the influence of vicariance and host association on the genetic structure of two generalist flea species, Listropsylla agrippinae, and Chiastopsylla rossi. The taxa differ in the time spent on the host (fur vs. nest) and the level of host specificity; (2) the taxonomy of Dinopsyllus ellobius to determine whether more than one species exist and if so to then elucidate the mechanisms of speciation; and (3) the influence of flea life history on species distribution model performance and see if the relative importance of predictor variables differ between species with different life histories. A total of 1423 small mammals were brushed to collect 2906 flea individuals originating from 31 geographically distinct localities throughout South Africa (SA). Phylogeographic structure of L. agrippinae and C. rossi were determined by making use of 315 mitochondrial COII (mtDNA) and 174 nuclear EF1-α (nDNA) sequences. The more host specific fur flea, L. agrippinae, displayed pronounced spatial phylogeographic structure, based on mtDNA, which was congruent with host vicariance in the region. In contrast, the more generalist nest flea, C. rossi, showed a higher level of inter-populational divergence, based on mtDNA and nDNA, and this may be attributed to comparatively higher restrictions to dispersal when compared to the more specific fur flea. In an attempt to resolve the taxonomy of D. ellobius, 151 mtDNA and 68 nDNA alleles were generated from individuals meeting the morphological description of D. ellobius. Two distinct D. ellobius lineages that corresponded to previously described species (D. ellobius and D. abaris) were recorded. The results indicate that the two species indeed differ morphologically and based on the distribution of the two species it was concluded that the diversification could be a result of climate driven vicariance and subsequent ecological segregation according to habitat use. Locality records from Segerman (1995) were digitized and used as background data in species distribution modelling. Sufficient information was obtained for 21 flea species. A total of 68 climatic and landscape feature predictor variables were obtained and through a process of elimination, 19 variables were ultimately used. Model performance was good to excellent on average and the contribution of climate and landscape feature variables differed between fleas with different life histories. Historical and contemporary climate has the most prominent effect on flea distribution at the regional scale, but the level of host association influences the phylogeographic pattern of fleas. This study provides the first evidence of congruent phylogeographic patterns between a generalist temporary parasite and its hosts. Our findings provide further support for the notion that more than one species exist within the D. ellobius complex and that speciation is a result of complex interactions. The study also provides novel data on the role of environmental variables in shaping the geographic distribution of flea species with different life histories. With the anticipated rise in flea-borne diseases worldwide, due to changes in vector distribution, the study further emphasize the need for studying the mechanisms involved in shaping flea distribution patterns.AFRIKAANSE OPSOMMING: Vlooie (Siphonaptera) is verpligte ektoparasiete van soogdiere en voëls. As gevolg van hul ekonomiese belangrikheid as vektore van oordraagbare siektes, neem meeste kontemporêre studies oor makroparasiete nou die ruimtelike variasie (vikariansie) van parasiet gemeenskappe en die onderliggende meganismes betrokke by die vorming van die huidige verspreiding patrone in ag. Vlooie verskil in lewensgeskiedenis eienskappe, soos die graad van gasheer spesifisiteit en mikrohabitat voorkeur, wat kan lei tot differensiële evolusionêre patrone tot soortgelyke abiotiese gebeure. Die belangrikste doelwitte van hierdie studie is om ondersoek in te stel na: (1) die invloed van vikariansie en gasheer assosiasie op die genetiese struktuur van twee algemene vlooi spesies, Listropsylla agrippinae en Chiastopsylla rossi. Die taxa verskil in die hoeveelheid tyd wat gespandeer word op die gasheer (pels vs. nes) en die graad van gasheer spesifisiteit; (2) die taksonomie van Dinopsyllus ellobius om te bepaal of daar meer as een spesie bestaan, en indien wel, die meganismes van spesiasie voortbring; en (3) die invloed van vlooi lewensgeskiedenis op die prestasie van die spesies verspreidings model en kyk of die relatiewe belangrikheid van omgewingsvoorspellers verskil tussen spesies met verskillende lewensgeskiedenisse. 'n Totaal van 1423 klein soogdiere is geborsel om 2906 vlooi individue afkomstig van 31 geografies verskillende plekke in Suid-Afrika in te samel. Filogeografiese struktuur van L. agrippinae en C. rossi is bepaal deur gebruik te maak van 315 mitochondriale COII (mtDNA) en 174 kern EF1-α (nDNA) volgorde bepalings. Die meer gasheer spesifieke pels vlooi, L. agrippinae, het ruimtelike filogeografiese struktuur aangetoon, gebaseer op mtDNA, wat ooreenstem met gasheer vikariansie in die streek. In teenstelling hiermee het die minder gasheer spesifieke nes vlooi, C. rossi, 'n hoër vlak van inter-populasie divergensie getoon, gebaseer op mtDNA en nDNA, wat toegeskryf kan word aan relatief hoër beperkings op verspreiding teenoor die meer gasheer spesifieke pels vlooi. In 'n poging om die taksonomie van D. ellobius op te los is 151 mtDNA en 68 nDNA allele gegenereer uit individue wat voldoen aan die morfologiese beskrywing van D. ellobius. Twee afsonderlike D. ellobius afstammelinge wat ooreengestem het met voorheen beskryfde spesies (D. ellobius en D. abaris) is aangeteken. Die resultate dui daarop dat die twee spesies inderdaad morfologies verskil en gebaseer op die verspreiding van die twee spesies is daar tot die gevolgtrekking gekom dat die diversifikasie moontlik toegeskryf kan word aan klimaat gedryfde vikariansie en daaropvolgende ekologiese segregasie volgens habitat gebruik. Geografiese verspreidings rekords van Segerman (1995) was gedigitaliseerd en gebruik as agtergrond data in die spesie verspreidings modelle. 'n Totaal van 68 klimaat en landskap kenmerk voorspeller veranderlikes is verkry, en deur 'n proses van eliminasie, is 19 veranderlikes gebruik. Model prestasie was oor die algemeen goed tot uitstekend en die bydrae van klimaat en landskaps veranderlikes het verskil tussen vlooie met verskille in lewensgeskiedenis. Historiese en kontemporêre klimaat het die mees prominente effek op vlooi verspreiding by die plaaslike skaal, maar die vlak van die gasheer assosiasie beïnvloed die filogeografiese patroon van vlooie. Hierdie studie bied die eerste getuienis van ooreenstemmende filogeografiese patrone tussen 'n minder gasheer spesifieke, tydelike parasiet en sy gashere. Ons bevindinge bied verdere ondersteuning vir die idee dat meer as een spesie bestaan binne die D. ellobius kompleks en dat spesiasie 'n gevolg is van komplekse interaksies. Die studie bied ook nuwe data oor die bydrae van die omgewingsveranderlikes in die vorming van die geografiese verspreiding van vlooi spesies met verskillende lewensgeskiedenisse. Met die verwagte styging in vlooi-oordraagbare siektes wêreldwyd, as gevolg van veranderinge in vektor verspreiding, beklemtoon die studie verder die noodsaaklikheid vir die bestudering van die meganismes betrokke in die vorming van vlooi verspreiding patrone.National Research Foundation (NRF
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