Niche Constructors Research Articles

Uncovering the Holocene roots of contemporary disease-scapes: bringing archaeology into One Health.

The accelerating pace of emerging zoonotic diseases in the twenty-first century has motivated cross-disciplinary collaboration on One Health approaches, combining microbiology, veterinary and environmental sciences, and epidemiology for outbreak prevention and mitigation. Such outbreaks are often caused by spillovers attributed to human activities that encroach on wildlife habitats and ecosystems, such as land use change, industrialized food production, urbanization and animal trade. While the origin of anthropogenic effects on animal ecology and biogeography can be traced to the Late Pleistocene, the archaeological record-a long-term archive of human-animal-environmental interactions-has largely been untapped in these One Health approaches, thus limiting our understanding of these dynamics over time. In this review, we examine how humans, as niche constructors, have facilitated new host species and 'disease-scapes' from the Late Pleistocene to the Anthropocene, by viewing zooarchaeological, bioarchaeological and palaeoecological data with a One Health perspective. We also highlight how new biomolecular tools and advances in the '-omics' can be holistically coupled with archaeological and palaeoecological reconstructions in the service of studying zoonotic disease emergence and re-emergence.

Earthen mounds (heuweltjies) of South Africa and their termite occupants: applicability of concepts of the extended phenotype, ecosystem engineering and niche construction.

Heuweltjies are earthen mounds found throughout the Succulent Karoo of South Africa and are inhabited by the termite Microhodotermes viator. Many have assumed that heuweltjies are constructed by the occupying termites. Consequently, heuweltjies have been used as an example of several important concepts in ecology and evolution: the extended phenotype, ecosystem engineering and niche construction. However, recent findings demonstrate that M. viator does not directly construct heuweltjies. Rather, termite colonies enrich the soil around their nests with plant nutrients, which promotes development of widely separated patches of denser vegetation. Eventual formation of heuweltjies represents a response of the physical environment to the windbreak effect of the denser vegetation patches (localized reduction of wind velocity and resultant deposition and accumulation of airborne sediment). Other structures constructed by the termites are justifiably regarded as extended phenotypes. Identification and investigation of a complex cascade of processes are required to more precisely assess the manner in which this termite species functions as an ecosystem engineer or niche constructor, thereby significantly influencing the availability of resources within local ecosystems. Environmental alterations that are either directly or indirectly generated by social animals that construct large, communal nests represent ecological processes that contribute significantly to local biodiversity. This article is part of the theme issue 'The evolutionary ecology of nests: a cross-taxon approach'.

THE TURUCHAN PIKA (<i>OCHOTONA TURUCHANENSIS</i>) AS AN ECOSYSTEM ENGINEER: THE INFLUENCE ON THE GROWTH OF THE COMMON NETTLE (<i>URTICA DIOICA</i>) ON TALUSES

The abundance of the common nettle on taluses was found to be strongly correlated with the abundance of such signs of Turuchan pika activities as feces, latrines, and haypiles collected by pikas under stones. We believe this is the activities of pikas that provide nitrates and thus facilitate the growth of the common nettle, a ruderal nitrophilous plant, on taluses. On the other hand, pikas selectively store nettles. As a result, pikas can be considered as both “ecosystem engineer” and “niche constructors”.

Niche construction in quantitative traits: heritability and response to selection.

A central tenet of niche construction (NC) theory is that organisms can alter their environments in heritable and evolutionarily important ways, often altering selection pressures. We suggest that the physical changes niche constructors make to their environments may also alter trait heritability and the response of phenotypes to selection. This effect might change evolution, over and above the effect of NC acting via selection alone. We develop models of trait evolution that allow us to partition the effects of NC on trait heritability from those on selection to better investigate their distinct effects. We show that the response of a phenotype to selection and so the pace of phenotypic change can be considerably altered in the presence of NC and that this effect is compounded when trans-generational interactions are included. We argue that novel mathematical approaches are needed to describe the simultaneous effects of NC on trait evolution via selection and heritability. Just as indirect genetic effects have been shown to significantly increase trait heritability, the effects of NC on heritability in our model suggest a need for further theoretical development of the concept of heritability.

A Framework for the Eltonian Niche of Humans

AbstractRecent research has highlighted several influential roles that humans play in ecosystems, including that of a superpredator, hyperkeystone species, and niche constructor. This work has begun to describe the Eltonian niche of humans, which encompasses humanity's cumulative ecological and evolutionary roles in trophic systems. However, we lack a unifying framework that brings together these strands of research, links them to ecoevolutionary and sociocultural theory, and identifies current research needs. In this article, we present such a framework in hope of facilitating a more holistic approach to operationalizing human roles in trophic systems across an increasingly anthropogenic biosphere. The framework underscores how humans play numerous nuanced roles in trophic systems, from top-down to bottom-up, that entail not only pernicious effects but also benefits for many nonhuman species. Such a nuanced view of the Eltonian niche of humans is important for understanding complex social–ecological system functioning and enacting effective policies and conservation measures.

Niche construction mediates climate effects on recovery of tundra heathlands after extreme event

Climate change is expected to increase the frequency and intensity of extreme events in northern ecosystems. The outcome of these events across the landscape, might be mediated by species effects, such as niche construction, with likely consequences on vegetation resilience. To test this hypothesis, we simulated an extreme event by removing aboveground vegetation in tundra heathlands dominated by the allelopathic dwarf shrub Empetrum nigrum, a strong niche constructor. We tested the hypothesis under different climate regimes along a 200-km long gradient from oceanic to continental climate in Northern Norway. We studied the vegetation recovery process over ten years along the climatic gradient. The recovery of E. nigrum and subordinate species was low and flattened out after five years at all locations along the climatic gradient, causing low vegetation cover at the end of the study in extreme event plots. Natural seed recruitment was low at all sites, however, the addition of seeds from faster growing species did not promote vegetation recovery. A soil bioassay from 8 years after the vegetation was removed, suggested the allelopathic effect of E. nigrum was still present in the soil environment. Our results provide evidence of how a common niche constructor species can dramatically affect ecosystem recovery along a climatic gradient after extreme events in habitats where it is dominant. By its extremely slow regrowth and it preventing establishment of faster growing species, this study increases our knowledge on the possible outcomes when extreme events harm niche constructors in the tundra.

The emergence and intensification of early hunter-gatherer niche construction.

Hunter-gatherers, especially Pleistocene examples, are not well-represented in archeological studies of niche construction. However, as the role of humans in shaping environments over long time scales becomes increasingly apparent, it is critical to develop archeological proxies and testable hypotheses about early hunter-gatherer impacts. Modern foragers engage in niche constructive behaviors aimed at maintaining or increasing the productivity of their environments, and these may have had significant ecological consequences over later human evolution. In some cases, they may also represent behaviors unique to modern Homo sapiens. Archeological and paleoenvironmental data show that African hunter-gatherers were niche constructors in diverse environments, which have legacies in how ecosystems function today. These can be conceptualized as behaviorally mediated trophic cascades, and tested using archeological and paleoenvironmental proxies. Thus, large-scale niche construction behavior is possible to identify at deeper time scales, and may be key to understanding the emergence of modern humans.

Expansion, Exploitation and Extinction: Niche Construction in Ephemeral Landscapes

We aim to understand general consequences of niche construction on metapopulation dynamics in ephemeral landscapes. To this effect, a contact process-like stochastic spatial model is introduced where local populations colonize and go extinct on a dynamic landscape of habitable and destroyed patches. In contrast to previous models, where the extinction threshold is a consequence of available niche rendered by global rates of patch destruction/renewal, here we investigate how the metapopulation persists when they are the sole generators of their own niche. Niche construction is full-filled by localized populations through the transformation of destroyed patches in their neighborhood to viable habitat for future colonization. With this theoretical framework we are able to address the dual nature of niche construction by investigating the ephemerality of the landscape (destruction rate) and the continuum of population level strategies, where construction comes at a cost to colonization. Using mean field theory and Monte Carlo simulations of the model, we are able to quantify optimal population level strategies in a wide range of ephemeral landscapes. Interestingly, we observe qualitative differences at the extinction threshold between analytic and numeric results. Investigating this discrepancy further, we find that increasing niche construction neighborhood in the spatial model leads to two interrelated effects i) an increased rate in range expansion ii) a loss in resiliency and return of the discontinuous transition at the extinction threshold. Furthermore, in the discontinuous regime of the model, spatial clustering prior to a critical transition disappears. This is a significant finding as spatial clustering has been considered to be an early warning signal before ecosystems reach their ‘tipping point’. In addition to maintaining stability, we find local niche construction strategies have an advantage when in scramble competition with an exploiter strategy because of their ability to monopolize the constructed niche due to spatial adjacency. As the niche construction neighborhood expands this advantage disappears and the exploiter strategy out-competes the niche constructor. In some cases the exploiter pushes the niche constructor to extinction, thus a tragedy of the commons ensues leading to ‘ecological suicide’ and a collapse of the niche.

Tall Shrubs Mediate Abiotic Conditions and Plant Communities at the Taiga–Tundra Ecotone

Shrub expansion has occurred across much of the arctic tundra over the past century. Increasing dominance of woody vegetation is expected to have global influences on climate patterns and lead to local changes in hydrological function and nutrient cycling. Changing abiotic conditions associated with shrubs will likely alter the relative fitness of neighbouring plants resulting in distinct community composition. Here, we use an extensive set of paired abiotic and biotic data to investigate the capacity for Alnus alnobetula (green alder) patches to modify the habitat of the local plant community at the taiga–tundra ecotone of the Northwest Territories, Canada. Plots were established across topographic positions in ten alder patches and adjacent, alder-free tundra. Habitat corresponded to the strongest gradient of among-site variation in abiotic measures and plant community composition, indicating that alder patch growing conditions were distinct from those of alder-free tundra. Slope position was generally unimportant in determining environmental conditions. Alder patches changed the vertical structure of the understory by increasing the maximum height of birch. Tall shrubs also decreased the richness of tundra specialists, suggesting that these species face competitive pressures from shrub expansion at the southern edge of their ranges. Our findings demonstrate that tall shrub patches can substantially modify their local environment in taiga–tundra ecotone systems, altering available habitat and acting as niche constructors for the local plant community. These habitats will therefore be important to consider in regional predictions of hydrology, nutrient cycling, and biodiversity as shrubs continue to expand across the arctic.

The Role of Pleiotropy in the Evolutionary Maintenance of Positive Niche Construction.

Organisms often modify their environments to their advantage through a process of niche construction. Environments that are improved through positive niche construction can be viewed as a public good. If free riders appear that do not contribute to the shared resource and therefore do not incur any associated costs, the constructed niche may become degraded, resulting in a tragedy of the commons and the extinction of niche constructors. Niche construction can persist if free riders are excluded, for example, if niche constructors monopolize the resource they produce to a sufficient degree. We suggest, however, that the problem of free riders remains because it is possible that nonniche constructors with an enhanced ability to access the resource appear and invade a population of constructors. Using mathematical models we show that positive niche construction can be maintained if it is inextricably linked to a mechanism that makes free riding costly, such as a trait that confers a benefit to only niche constructors. We discuss this finding in terms of genetic interactions and illustrate the principle with a two-locus model. We conclude that positive niche construction can both evolve and be maintained when it has other beneficial effects via pleiotropy. This situation may apply generally to the evolutionary maintenance of cooperation.

We're on a road to nowhere: Culture and adaptation to the environment are driving human evolution, but the destination of this journey is unpredictable.

It is tempting to believe that humans, owing to their technological prowess, have elevated themselves above the laws of biology and escaped natural selection. Indeed, some think that humans have stopped evolving at all. Another view holds that Homo sapiens has not isolated itself from the influences of the physical and biological world but that our species is just a special, extreme case of niche constructors. This view is based on the so‐called Niche Construction Theory, a development within evolutionary biology to describe how humans—and many other organisms—modify their environment—or niche—in a way that alters environmental pressures and therefore natural selection. Thus, rather adapting to a pre‐existing environment, “organisms drive environmental change and organism‐modified environments subsequently select organisms” (https://synergy.st-andrews.ac.uk/niche/niche-construction-and-evolution/) (Box 1). ### Culture‐driven evolution “[All] organisms adapt to their environment, and in humans much of our environment is defined by our culture. Hence, cultural change can actually spur on adaptive evolution in humans”, wrote evolutionary biologist Alan Templeton at Washington University in St. Louis, MO, USA. [1]. Following this argument, culture, social learning and technology have not replaced biological adaptation. Rather, human evolution is driven by the environmental conditions we created ourselves through culture, a process that has been accelerating since the beginning of agriculture and urban civilization. In other words, cultural niche construction is a major cause of recent human evolution. However, there are other factors than natural selection, such as genetic drift and gene flow, that influence human evolution [1]. Nonetheless, even the effects of these random, non‐adaptive forces on human genetic variation are somehow altered by cultural trends, namely increased urbanization and greater mobility. As a consequence, drift is diminishing and gene flow is increasing, a process that would eventually culminate into a single “species‐wide” gene pool characterized by high levels of genetic variation. > [C]ulture, …

Gatekeepers to the effects of climate warming? Niche construction restricts plant community changes along a temperature gradient

Organisms that modify the environment (niche constructors) are likely candidates to mediate the effects of climate warming. Here we assess tundra plant community changes along a temperature gradient and how these are modified in the presence of the common allelopathic dwarf shrub Empetrum nigrum and the large herbivore Rangifer tarandus.We developed a structural equation model based on data from a field-based study of 1450 tundra plant communities across Northern Fennoscandia, covering a temperature gradient of 3.5 °C, contrasting Rangifer densities, a range of Empetrum abundances in addition to gradients in topography and bedrock.We found temperature to be a significant positive predictor of Empetrum, herbaceous and woody plant abundances. However, the effect of temperature as predictor for herbaceous plant abundance was significantly reduced in communities with Empetrum present. For woody plant abundance Empetrum was a stronger predictor than temperature. In comparison, we found Rangifer density to have marginal or no effect on either herbaceous or woody plant abundance. These findings were not modified by either topography or bedrock.Results from this study indicate that herbaceous plant responses to climate warming are currently reduced in communities where Empetrum is present, whereas the abundance of Empetrum and other woody plants is promoted. Results also indicate that any future Empetrum encroachment is likely to drive tundra communities towards slower process rates and lower biodiversity. As such our results substantiate the importance of understanding the dynamics of niche constructor species and include them in predictive models of climate change.

The role of food storage in human niche construction: An example from Neolithic Europe

Niche construction theory, a branch of evolutionary biology, places emphasis on the capacity of organisms, through their metabolism, activities and choices, to modify natural selection in their environment and thereby act as co-directors of their own evolution as well as that of others. Humans are potent niche constructors, and understanding how niche construction regulates ecosystem dynamics is central to understanding the impact of human populations on their ecological and developmental environments. A classic example is provided by the evolution of dairying by Neolithic groups in Europe and the significant role played by storage in the development of the dairying niche.

Sámi reindeer herders' perspective on herbivory of subarctic mountain birch forests by geometrid moths and reindeer: a case study from northernmost Finland.

IntroductionGeometrid moths and semi-domesticated reindeer are both herbivores which feed on birch leaves in the subarctic mountain birch forests in northern Fennoscandia. The caterpillars of autumnal and winter moths have episodic outbreaks, which can occasionally lead to extensive defoliation of birch forests. Earlier studies have shown that reindeer have a negative effect on the regeneration of defoliated birches by grazing and browsing their seedlings and sprouts.Case descriptionWe interviewed 15 reindeer herders in the Kaldoaivi and Paistunturi herding co-operative in northernmost Finland in order to analyse their past, present and future views on the behaviour of moths and the growth of mountain birches. We investigate the behaviour of the two herbivores by combining the indigenous knowledge (IK) of Sámi herders with the results of relevant studies in biology and anthropology, applying niche construction theory (NCT) in doing so.Discussion and evaluationIn the first stage, the niche constructors (moths, reindeer, herders, mountain birch and other organisms) are looked upon as “equal constructors” of a shared niche. As changes unfold in their niche, their role changes from that of constructor to key constructor. The role and importance of niche constructors were different when nomadic pasture rotation was used than they are today under the herding co-operative system. Niche construction faced its most radical and permanent negative changes during the border closures that took place over the latter half of the 19th century. The large-scale nomadic life among the Sámi herders, who migrated between Finland and Norway, came to an end. This phase was followed by stationary herding, which diminished the possibilities of reindeer to look for various environmental affordances. Difficult snow conditions or birch defoliation caused by moth outbreaks made the situation worse than before. Eventually reindeer became key constructors, together with moth larvae, leading to negative ecological inheritance that forced herders to use new, adaptive herding practices.ConclusionsBoth the scientific data and the IK of herders highlight the roles of reindeer and herders as continuous key constructors of the focal niche, one which stands to be modified in more heterogenic ways than earlier due to global warming and hence will result in new ecological inheritance.

Niche construction by growth forms is as strong a predictor of species diversity as environmental gradients

Summary We present a conceptual framework that describes how species belonging to a growth form collectively can be niche constructors (i.e. modify niches) and affect species diversity in plant communities. We use an empirical assessment of tundra plant communities to illustrate the framework's utility. In doing so, we make a first investigation of collective niche construction in ecological communities. In tundra plant communities, growth forms differently affect ecosystem process rates and cause environmental modifications; thus, growth forms are strong candidates for being niche constructors. To assess the impact of growth form niche construction on plant species diversity, we excluded the species of the growth form applied as niche constructor when estimating the community species diversity. We assessed niche construction in 70 tundra meadow communities and 1450 randomly selected tundra plant communities that are distributed along ecological gradients in temperature, resource availability, competitive interference and herbivory. These gradients allowed us to concomitantly assess to what extent the niche construction is independent of environmental conditions. Growth forms varied from strong positive to neutral predictors of both species richness and Simpson index in the order of forbs, grasses, sedges, deciduous shrubs and evergreen shrubs, suggesting that growth forms have important roles as niche constructors in tundra plant communities. Also, the environmental conditions were strong predictors of species diversity, but they did not interact with or confound the effects of growth forms. Forbs and grasses were the least abundant growth forms, yet they were the strongest positive predictors of species diversity. Therefore, our results suggest a particular niche‐constructing role of these growth forms for enhancing species diversity in tundra plant communities. Synthesis. In this study, we provide conceptual and empirical evidence for collective niche construction as a powerful ecological process that affects species diversity and that can act independently of environmental conditions. Species sharing a single trait or species belonging to a growth form can act as collective niche constructors, and as exemplified for growth forms in this study, be important predictors of species diversity in ecological communities.

Brown bears (Ursus arctos) as ecological engineers: the prospective role of trees damaged by bears in forest ecosystems

Brown bears (Ursus arctos L., 1758) damage trees (mainly the cambium) during feeding and marking. It is thought that their stripping of bark and their subsequent foraging on sapwood can lead to substantial economic losses. However, the part played by this process in the ecosystem is still unknown. We hypothesize that brown bear foraging makes resources and habitats available to other species. We anticipated that wounds perpetrated by bears during foraging would attract saproxylic insects and consequently insectivorous birds. Bear wounds were searched for on trees in the Bieszczady Mountains (Polish Eastern Carpathians) from 2008 to 2011. We analyzed 278 wounds in silver firs (Abies alba Mill.) of different age classes: 43% of them had holes made by wood-boring insects and 33% had signs of woodpecker feeding. The presence of insect holes and woodpecker marks in the wound was found to depend on wound area, wound age, and tree circumference (insects only). In particular, the oldest wound age class (>5 years old) was associated with a high probability of occurrence of insects and woodpeckers. Insects were attracted by wounds of smaller area than woodpeckers. The density of insect holes (number of wood-boring insects) depended on the wound age and tree circumference. Insect densities in fresh wounds (<1 year old) were significantly lower than in the older age classes. The results show that bear-made wounds provide breeding and feeding sites for both insects and birds. Especially for woodpeckers (forest indicator species) and for saproxylic insects (mainly endangered species), brown bears may play an important role as niche constructors and ecological engineers. Therefore, it would be advisable to leave a considerable number of bear-wounded trees in the forest ecosystems for conservation purposes.

Rapid evolution of adaptive niche construction in experimental microbial populations.

Many species engage in adaptive niche construction: modification of the local environment that increases the modifying organism's competitive fitness. Adaptive niche construction provides an alternative pathway to higher fitness, shaping the environment rather than conforming to it. Yet, experimental evidence for the evolutionary emergence of adaptive niche construction is lacking, leaving its role in evolution uncertain. Here we report a direct observation of the de novo evolution of adaptive niche construction in populations of the bacteria Pseudomonas fluorescens. In a laboratory experiment, we allowed several bacterial populations to adapt to a novel environment and assessed whether niche construction evolved over time. We found that adaptive niche construction emerged rapidly, within approximately 100 generations, and became ubiquitous after approximately 400 generations. The large fitness effect of this niche construction was dominated by the low fitness of evolved strains in the ancestrally modified environment: evolved niche constructors were highly dependent on their specific environmental modifications. Populations were subjected to frequent resetting of environmental conditions and severe reduction of spatial habitat structure, both of which are thought to make adaptive niche construction difficult to evolve. Our finding that adaptive niche construction nevertheless evolved repeatably suggests that it may play a more important role in evolution than generally thought.

Biotic modifiers, environmental modulation and species distribution models

AbstractThe ability of species to modulate environmental conditions and resources has long been of interest. In the past three decades the impacts of these biotic modifiers have been investigated as ‘ecosystem engineers’, ‘niche constructors’, ‘facilitators’ and ‘keystone species’. This environmental modulation can vary spatially from extremely local to global, temporally from days to geological time, and taxonomically from a few to a very large number of species. Modulation impacts are pervasive and affect, inter alia, the climate, structural environments, disturbance rates, soils and the atmospheric chemical composition. Biotic modifiers may profoundly transform the projected environmental conditions, and consequently have a significant impact on the predicted occurrence of the focal species in species distribution models (SDMs). This applies especially when these models are projected into different geographical regions or into the future or the past, where these biotic modifiers may be absent, or other biotic modifiers may be present. We show that environmental modulation can be represented in SDMs as additional variables. In some instances it is possible to use the species (e.g. biotic modifiers) in order to reflect the modulation. This would apply particularly to cases where the effect is the result of a single or a small number of species (e.g. elephants transforming woodland to grassland). Where numerous species generate an effect (such as tree species making a forest, or grasses facilitating fire) that modulates the abiotic environment, the effect itself might be a better descriptor for the aggregated action of the numerous species. We refer to this ‘effect’ as the modulator. Much of the information required to incorporate environmental modulation effects in SDMs is already available from remote‐sensing data and vegetation models.

Genes, Culture, and Agriculture

Theory and empirical data from a variety of disciplines strongly imply that recent human history involves extensive gene-culture coevolution, much of it as a direct result of human agricultural practices. Here we draw on niche-construction theory (NCT) and gene-culture coevolutionary theory (GCT) to propose a broad theoretical framework (NCT-GCT) with which archaeologists and anthropologists can explore coevolutionary dynamics. Humans are enormously potent niche constructors, and understanding how niche construction regulates ecosystem dynamics is central to understanding the impact of human populations on their ecological and developmental environments. We use as primary examples the evolution of dairying by Neolithic groups in Europe and Africa and the rise of the “sickle-cell allele” among certain agricultural groups in West Africa and suggest that these examples are broadly representative of much of human recent history. Although the core aspects of these case studies are familiar, we lay out the exam...

Two Proposals

Proposal 1: Anthropology Beyond the Human Eduardo Kohn Ethnographic attention to human-animal relations in Amazonia reveals the constitutively semiotic nature of all life.This helps us appreciate more broadly the ways in which semiotic logics that are not necessarily human or language-like underlie the modes by which thoughts and lives form associations. This changes our understanding of relationality, arguably anthropology’s central concern. Proposal 2: Humans as Niche Constructors, as Primates and with Primates: Synergies for Anthropology in the Anthropocene Agustín Fuentes Humans are primates and consummate niche constructors. If we hope to be both relevant and successful investigators in the multispecies word of the Anthropocene, we need an anthropological practice that places humans and other organisms in integrated and shared ecological and social spaces. Ethnoprimatology and a constructivist evolutionary theory help us move towards a place where the biological and social are folded into an integrative anthropology, in which a myriad of entangled agents and theoretical perspectives are central in investigating the processes of becoming human.