ArticleLiterature Review

Movers and Stayers: Novel Assemblages in Changing Environments

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Abstract

Increased attention to species movement in response to environmental change highlights the need to consider changes in species distributions and altered biological assemblages. Such changes are well known from paleoecological studies, but have accelerated with ongoing pervasive human influence. In addition to species that move, some species will stay put, leading to an array of novel interactions. Species show a variety of responses that can allow movement or persistence. Conservation and restoration actions have traditionally focused on maintaining or returning species in particular places, but increasingly also include interventions that facilitate movement. Approaches are required that incorporate the fluidity of biotic assemblages into the goals set and interventions deployed.

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... Contrary to expectations, climate change is not causing a systematic loss of biodiversity (Dornelas et al. 2014) instead, a complex response with species turnover and the emergence of novel communities' configurations is happening (Hobbs et al. 2006;McLean et al. 2021). This reconfiguration and redistribution of species are challenging a traditional management approach that aims at maintaining or returning species to a particular location (Hobbs et al. 2018;Vergés et al. 2019). To secure the ecosystem services coming from these reconfigured natural systems, it is important to create new management approaches that require understanding the mechanisms driving these new configurations (Hobbs et al. 2018). ...
... This reconfiguration and redistribution of species are challenging a traditional management approach that aims at maintaining or returning species to a particular location (Hobbs et al. 2018;Vergés et al. 2019). To secure the ecosystem services coming from these reconfigured natural systems, it is important to create new management approaches that require understanding the mechanisms driving these new configurations (Hobbs et al. 2018). ...
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Globally, marine communities are experiencing gradual warming and extreme heatwaves causing species to shift in geographic range. As a result, the biological assemblages outside tropical latitudes are being reorganized or "tropicalized" as warm-affinity species become increasingly dominant and cool water species recede, with impacts on our economies, food supply, and health. In the Gulf of California, existing oceanographic discontinuities shape marine communities by creating different assemblages according to environmental affinities. In this study, we show how a known ecological boundary underwent a northward shift of 1.5°latitude because of an average 1°C gradual warming over the last decade (2010-2020) and extreme marine heatwaves threefold more frequent. Such shift homogenized environmental conditions and reconfigured rocky reefs communities. Fish biomass decreased of 43%, whereas invertebrates, which recorded a 35% decrease in overall abundance, showed different community configurations depending on the climate regime. Stony coral species with warm water affinities increased with a reduction of cold-water species during the last El Niño. The long-term consequences of the tropi-calization of these rocky reefs' communities are still uncertain. This study underlines the importance of long-term monitoring of key habitats to quantify, predict, and adapt to future climatic stresses.
... 164,165,166 For example, it remains largely uncertain which members of historical ecological communities and ecosystems will adapt in place or move into new locations to follow optimal ecological and environmental conditions. 167 Such uncertainties complicate management decisions regarding where and when human intervention is advisable to assist persistence. ...
... It is also unclear how the restructuring of ecosystems will manifest in terms of the functioning and delivery of ecosystem services. 167,168 For example, along the Northeast Atlantic coast, native fiddler and blue crabs have shifted their ranges north and are now found in New England coastal habitats where they were previously absent. 169,170 These two species join an assemblage of native and invasive crab species, which are responding to changes in environmental and ecological conditions in different ways. ...
... Changes in rural land-use have diverse implications for the biota: some species experience population decline or loss from the region, while others flourish, and new species may colonise (Hobbs et al. 2018). Concern about faunal decline in rural regions, especially of birds, has been widely documented across continents (Villard et al. 1999;Donald et al. 2001;Ford et al. 2001;Jetz et al. 2007). ...
... These results illustrate the different ways in which species respond to changing environments. Some species will persist only in landscapes dominated by natural habitat (Saunders et al. 1991;Barrett et al. 1994), some species will adapt to or re-occupy modified landscapes and form part of novel assemblages; and some species may persist in the short-term but become locally extinct without human intervention (Hobbs et al. 2018). Examples of these responses were evident in this study: for example, the superb lyrebird was recorded only in natural forest landscapes, the grey fantail was common across all modified landscapes, and a previously abundant forest species, the satin bowerbird (Ptilonorhynchus violaceus) (Elms 1920b), was not detected. ...
Article
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Rural landscape change as a consequence of human population growth is a major challenge for nature conservation in the twenty-first century. Rural regions are globally experiencing change driven by diverse factors, including agricultural intensification, new agricultural commodities, residential development, and land abandonment. Understanding how different land-use trajectories affect biodiversity is critical for making informed decisions for the conservation of species in modified environments. We examined the impact of different land-uses on bird communities in the western Strzelecki Ranges, a formerly forested but now rural region in south-east Australia. We selected 25 study landscapes, each 1 km², representing seven land-uses typical of rural regions: townships, lifestyle properties (low-density acreages or hobby farms), dairy farming, beef grazing, horticulture, tree plantation and natural forest. Terrestrial birds were systematically surveyed at 10 sites in each study landscape and the results pooled to represent the whole landscape. We recorded 80 native and 8 exotic species of birds, of which 46 species were classified a priori as forest species typical of the region. Different trajectories of land-use have generated variation in landscape structure, with a primary gradient of change from forest to rural townships. The composition of bird communities and the richness of four species-response groups showed marked differences across land-use types. The mean richness of forest species, for example, was greatest in natural forest land-use (30.0 species) and lowest in dairy farming land-use (14.5 species). Key lessons from this study include: (1) these diverse land-uses, typical of rural regions, are creating novel assemblages of birds that differ from that of the former forested environment; (2) land-use in this region is dynamic and so further re-assortment of bird communities can be expected through time; (3) despite such change, a component of the original forest avifauna persists, even in highly modified landscapes; and (4) each land-use type offers opportunities for nature conservation while also meeting the needs of people and agricultural production.
... Species redistributions and the resulting emergence of novel biological assemblages pose major challenges to traditional conservation and environmental management approaches, which typically focus on maintaining or returning species to particular locations (Hobbs, Valentine, Standish, & Jackson, 2017). As we are increasingly unable to protect or conserve historical conditions, new management approaches require understanding the mechanisms driving novel ecosystem configurations and how these changes impact the benefits that humans derive from our natural systems, so that we can secure ecosystem services into the future. ...
... Fundamental to our understanding of tropicalised temperate systems is that regardless of which trajectories are followed, these systems will represent novel ecosystem configurations. This poses major challenges, practically, legally and philosophically, to traditional approaches to conservation and environmental management, which typically focus on maintaining or returning species to particular locations (Hobbs et al., 2017;McDonald et al., 2019). Below, we consider both more traditional (Marine protected areas [MPAs]) and emerging ("assisted evolution") approaches to conservation of these ecosystems and briefly discuss some of the ethical considerations underlying choices of management approaches. ...
Article
1.Temperate reefs from around the world are becoming tropicalised, as warm‐water species shift their distribution towards the poles in response to warming. This is already causing profound shifts in dominant foundation species and associated ecological communities as canopy seaweeds such as kelp are replaced by tropical species. 2.Here, we argue that the cascading consequences of tropicalisation for the ecosystem properties and functions of warming temperate reefs depend largely on the taxa that end up dominating the seafloor. We put forward three potential tropicalisation trajectories, that differ in whether seaweeds, turf or corals become dominant. We highlight potential gains to certain ecosystem functions for some tropicalisation end‐points. For example, local benthic fish productivity may increase in some tropicalised reefs as a higher proportion of primary production is directly consumed, but this will be at the expense of other functions such as carbon export. We argue that understanding these changes in flows of energy and materials is essential to formulate new conservation strategies and management approaches that minimise risks as well as capture potential opportunities. 3.Regardless of which trajectory is followed, tropicalised systems represent largely novel ecosystem configurations. This poses major challenges to traditional conservation and environmental management approaches, which typically focus on maintaining or returning species to particular locations. We outline management practices that may either mitigate predicted structural and functional changes or make the most of potential new opportunities in tropicalised reefs. These include marine protected areas to increase resilience and connectivity, the development of new fisheries that target range‐expanding invaders, and assisted evolution and migration strategies to facilitate the dominance of large habitat formers like corals or seaweeds. 4.We highlight important ecological and ethical challenges associated with developing novel approaches to manage tropicalised reefs, which may need to become increasingly interventionist. As technological innovations continue to emerge, having clear goals and considering the ethics surrounding interventions among the broader community are essential steps to successfully develop novel management approaches. This article is protected by copyright. All rights reserved.
... C'est par exemple le cas du harfang des neiges, dont la proie de choix, le lemming, est de moins en moins abondante au moment de la période de reproduction des chouettes ( Fig.1, (Gilg et al., 2009;IUCN, 2017a)). Ces pressions exercées par les changements climatiques mènent certaines espèces à décaler progressivement, quand cela leur est possible, leur aire de répartition en latitude (en direction des pôles) ou en altitude (vers des altitudes plus élevées) pour retrouver des conditions thermiques similaires (Hobbs et al., 2018). Une étude menée sur les oiseaux communs européens suggère par exemple que les espèces se sont décalées vers le Nord de 37 km en moyenne entre 1990 et 2008, ce qui pourrait en partie être dû aux changements climatiques (Devictor et al., 2012). ...
... Enfin, la connectivité des aires protégées semble essentielle dans le contexte de changements climatiques qui conduit de nombreuses espèces à décaler leur aire de répartition (Devictor et al., 2012;Hobbs et al., 2018) si elles peuvent faciliter la colonisation de nouveaux sites plus propices. Cet effet de facilitation des aires protégées a été très clairement mis en évidence pour six espèces d'oiseaux de milieux aquatiques qui, décalant leur aire de répartition vers le nord, ont récemment colonisé la Grande-Bretagne. ...
Thesis
Les espoirs de stopper la crise actuelle de biodiversité reposent principalement sur les aires protégées, qui visent à écarter ou restreindre les activités humaines de ces sites. Malgré le rôle central que jouent les aires protégées dans les stratégies de conservation de la biodiversité, les études mesurant leur efficacité réelle à limiter la perte de biodiversité restent rares. Mesurer cette différence n’est pas si évident qu’il y paraît puisque cela nécessite de comparer la biodiversité de sites protégés et de sites témoins non-protégés (qui ne diffèrent que par leur statut de protection) et requiert donc l’utilisation de gros jeux de données, qui sont rares. Dans cette thèse, j’utilise plusieurs jeux de données publics, principalement issus de programmes de sciences participatives, pour mesurer l’efficacité des aires protégées. Dans le premier chapitre, j’utilise des données d’abondance d’oiseaux issues de la « North American Breeding Bird Survey » et je montre que les aires protégées n’ont pas d’effet sur la richesse spécifique ou l’abondance totale mais qu’elles favorisent les espèces spécialistes. Dans le second chapitre, je me concentre sur les forêts tropicales de huit points chauds de biodiversité et j’utilise les données eBird pour montrer que les aires protégées ralentissent les déclins d’espèces d’oiseaux dépendantes des forêts, endémiques et menacées. De plus, je montre que cet effet sur les oiseaux est induit par le double effet qu’ont les aires protégées sur la réduction de la déforestation et de la dégradation de la forêt. Dans le troisième chapitre, je modélise la sensibilité à la pression humaine de chaque espèce d’oiseaux se reproduisant en Amérique et j’explore la capacité du réseau d’aires protégées à conserver les espèces les plus sensibles. Je montre que les zones où les espèces sont très sensibles (principalement dans les tropiques) sont souvent trop peu couvertes par des aires protégées intactes, laissant de nombreuses espèces sensibles sans aucun habitat protégé intact sur l’ensemble de leur aire de répartition. Enfin, dans le quatrième chapitre, j’interroge l’effet que peuvent avoir les aires protégées sur les comportements humains, en montrant que les habitants de municipalités françaises qui sont proches de parcs naturels adoptent plus de comportements pro-environnementaux. Dans leur ensemble, ces travaux de thèse soutiennent que les aires protégées peuvent constituer un outil efficace pour conserver la biodiversité et soulignent l’importance et la complexité de mesurer leur efficacité.
... At one end, managers might decide that current or predicted ecosystem changes are acceptable and no intervention is necessary. Even when facing unprecedented shifts in temperatures and disturbance regimes, some systems might be relatively well equipped to cope [41]. The Chihuahuan Desert grasslands, for instance, are surprisingly resilient to pulse perturbations [42], as are one of the largest nesting rookeries of loggerhead sea turtles (Caretta caretta) in West Africa [43]. ...
... On-the-ground strategies associated with these approaches are highly diverse and are not necessarily exclusive to RBM because; many were developed under different paradigms, including conservation, restoration, and even steady-state approaches [11]. The focus on ecosystem change demands not only that new strategies are developed [41,46] but also that they balance the need for adaptation with the possible emergence of undesirable outcomes. Introducing climate-adapted, novel ecosystem engineers into a system, for instance, can be more risky than adding novel, subordinate species because engineers are more likely to facilitate ecosystem transformations [19]. ...
Article
Resilience theory is increasingly applied to the management of global change impacts. There is growing concern, however, that misapplications of resilience-based management (RBM) can sometimes lead to undesirable outcomes. We address here an inescapable conundrum in the application of resilience theory: systems will need to track environmental change, but management that aims to support adaptive capacity can introduce undesirable levels of change. We provide a framework that links concepts from novel ecosystems and resilience theory to inform management of ecosystem change. We highlight that resilience-based applications need to address risks associated with novel human impacts to improve management outcomes.
... Adaptations to, and extinctions because of, environmental change will necessarily break up existing species interactions and create new ones [87]. For example, sudden changes such as dam construction can obstruct migration and lead to eco-evolutionary dynamics in the alewife-zooplankton system [88]. ...
Article
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“Everything changes and nothing stands still” (Heraclitus). Here we review three major improvements to freshwater aquatic ecosystem models — and ecological models in general — as water quality scenario analysis tools towards a sustainable future. To tackle the rapid and deeply connected dynamics characteristic of the Anthropocene, we argue for the inclusion of eco-evolutionary, novel ecosystem and social-ecological dynamics. These dynamics arise from adaptive responses in organisms and ecosystems to global environmental change and act at different integration levels and different time scales. We provide reasons and means to incorporate each improvement into aquatic ecosystem models. Throughout this study we refer to Lake Victoria as a microcosm of the evolving novel social-ecological systems of the Anthropocene. The Lake Victoria case clearly shows how interlinked eco-evolutionary, novel ecosystem and social-ecological dynamics are, and demonstrates the need for transdisciplinary research approaches towards global sustainability.
... These changes have probable implications on Rocky Mountain biodiversity. Habitat availability and suitability for multiple species has changed, which could entrain altitudinal range shifts (Parmesan and Yohe 2003), modified interspecific interactions (Heim et al. 2017;Pecl et al. 2017) and novel community assemblages (Hobbs et al. 2018). Given that the Rocky Mountains is an area of conservation importance for many species, monitoring of these land cover changes and resulting effects on biodiversity is essential to management efforts. ...
Article
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Abstract While orthogonal (i.e., aerial or satellite) imagery has become the more conventional source of land cover data because it can yield spatially accurate land cover maps, terrestrial oblique photographs present a valuable, relatively untapped source of raw optical data for studies of land cover change. We present a case study contrasting how these two types of imagery sample landscape composition and using repeat oblique photographs to evaluate long‐term land cover change in a remote region of the Canadian Rocky Mountains. We classified 46 historical oblique photographs and their corresponding modern repeats using the same discrete land cover classes employed in a Landsat‐based map of the same area. We compared landscape‐level composition estimates from both sources and regressed the land cover proportions from Landsat against the modern oblique images, hypothesizing a linear relationship for most classes. We found that the two sources sampled the landscape in broadly similar ways, with near‐concordance for dominant land cover classes, yet that oblique photographs more frequently detected narrow landscape features and estimated higher proportions of rock compared to satellite imagery, possibly due to the higher spatial resolution of the oblique photographs, and to their angle of incidence against steep slopes. We then evaluated land cover change from corresponding historical and repeat photographs and found that the landscape has homogenized over the past century via increased coniferous forest cover. Our work shows that terrestrial oblique photographs can be used to estimate landscape composition, particularly in mountain environments. This is helpful for analyzing past landscape conditions in historical photographs, monitoring decadal‐span landscape change and assessing habitat to model biodiversity through time.
... Moreover, the agricultural and urban matrices surrounding forest patches prevent some animals from recolonizing patches where they have been extirpated [20]. Thus, the re-establishment of ecological interactions even in large fragments is unlikely to occur without more active approaches, such as trophic rewilding [7,21]. ...
Article
Trophic rewilding has been suggested as a restoration tool to restore ecological interactions and reverse defaunation and its cascading effects on ecosystem functioning. One of the ecological processes that has been jeopardized by defaunation is animal-mediated seed dispersal. Here, we propose an approach that combines joint species distribution models with occurrence data and species interaction records to quantify the potential to restore seed-dispersal interactions through rewilding and apply it to the Atlantic Forest, a global biodiversity hotspot. Using this approach, we identify areas that should benefit the most from trophic rewilding and candidate species that could contribute to cash the credit of seed-dispersal interactions in a given site. We found that sites within large fragments bearing a great diversity of trees may have about 20 times as many interactions to be cashed through rewilding as small fragments in regions where deforestation has been pervasive. We also ranked mammal and bird species according to their potential to restore seed-dispersal interactions if reintroduced while considering the biome as a whole and at finer scales. The suggested approach can aid future conservation efforts in rewilding projects in defaunated tropical rainforests. This article is part of the theme issue ‘Trophic rewilding: consequences for ecosystems under global change’.
... Many ecological studies still sample at temporal and spatial scales that are smaller than the underlying processes (Estes et al., 2018), and management of forested landscapes based on shortterm observations may result in unanticipated consequences (Millar & Stephenson, 2015). This is especially important in forests where complex interactions between climate, disturbance and ecosystem resilience may cause plant communities to persist in areas where climate has become unsuitable for regeneration over time frames of years to decades (Dullinger et al., 2012;Hobbs, Valentine, Standish, & Jackson, 2017). ...
Article
Aim: Climate and disturbance alter forest dynamics, from individual trees to biomes and from years to millennia, leaving legacies that vary with local, meso‐ and macroscales. Motivated by recent insights in temperate forests, we argue that temporal and spatial extents equivalent to that of the underlying drivers are necessary to characterize forest dynamics across scales. We focus specifically on characterizing mesoscale forest dynamics because they bridge fine‐scale (local) processes and the continental scale (macrosystems) in ways that are highly relevant for climate change science and ecosystem management. We revisit ecological concepts related to spatial and temporal scales and discuss approaches to gain a better understanding of climate–forest dynamics across scales. Location: Eastern USA. Time period: Last century to present. Major taxa studied: Temperate broadleaf forests. Methods: We review regional literature of past tree mortality studies associated with climate to identify mesoscale climate‐driven disturbance events. Using a dynamic vegetation model, we then simulate how these forests respond to a typical climate‐driven disturbance. Results: By identifying compound disturbance events from both a literature review and simulation modelling, we find that synchronous patterns of drought‐driven mortality at mesoscales have been overlooked within these forests. Main conclusions: As ecologists, land managers and policy‐makers consider the intertwined drivers of climate and disturbance, a focus on spatio‐temporal scales equivalent to those of the drivers will provide insight into long‐term forest change, such as drought impacts. Spatially extensive studies should also have a long temporal scale to provide insight into pathways for forest change, evaluate predictions from dynamic forest models and inform development of global vegetation models. We recommend integrating data collected from spatially well‐replicated networks (e.g., archaeological, historical or palaeoecological data), consisting of centuries‐long, high‐resolution records, with models to characterize better the mesoscale response of forests to climate change in the past and in the future.
... geographic range sizes, the breakdown of ecological associations, and alterations in body size distributions (Darimont et al., 2015;Dirzo et al., 2014;Lyons et al., 2016;Hobbs et al., 2018;Wolf and Ripple, 2017;Smith et al., 2018). These changes are associated with defaunation, local extirpations, invasions and introductions, and global extinctions of wild populations (Boivin et al., 2016;Ceballos et al., 2017;Smith et al., 2015). ...
Article
This paper reviews how human impacts produced a marked shift from natural processes in the potential input of terrestrial mammals to the fossil record, both in composition of the mammal taxa and in processes controlling their preservation. These issues are key considerations in predicting the future fossil record of the modern vertebrate fauna and determining if there will be a resultant “Anthropocene” biostratigraphic unit. We show that a cosmopolitan fauna of humans and their domestic animals will dominate the potential fossil record. The chance of a wild animal becoming part of the fossil record has become very small. Instead, the future mammal record will be mostly cows, pigs, sheep, goats, dogs, cats, etc., and people themselves. The review also shows major unique anthropogenic impacts on the preservation potential of mammals. These impacts include alterations in the distribution and properties of natural sites of preservation, associated with shifts in land use and climate change; the production of novel sites for preservation, such as landfills and cemeteries; and changes in the biostratinomy of animal and human carcasses. Hunting and butchering produce distinctive bone fragments and assemblages. Use of large agricultural equipment and increased domestic animal density due to intensive animal farming likely increases the rate of and changes the kind of damage to bones. In sum, the mammalian fossil record of the modern era should be unique in Earth history and may help distinguish the boundary of the proposed Anthropocene time period.
... Current distributions may not reach their full range limits, and may be restricted in the future, due to human land use [42]. On the other hand, humans may assist migration, both intentionally and unintentionally [43]. Limited dispersal potential may also restrict the rate of range shifts [44]. ...
Article
We are in a period of relatively rapid climate change. This poses challenges for individual species and threatens the ecosystem services that humanity relies upon. Temperature is a key stressor. In a warming climate, individual organisms may be able to shift their thermal optima through phenotypic plasticity. However, such plasticity is unlikely to be sufficient over the coming centuries. Resilience to warming will also depend on how fast the distribution of traits that define a species can adapt through other methods, in particular through redistribution of the abundance of variants within the population and through genetic evolution. In this paper, we use a simple theoretical ‘trait diffusion’ model to explore how the resilience of a given species to climate change depends on the initial trait diversity (biodiversity), the trait diffusion rate (mutation rate), and the lifetime of the organism. We estimate theoretical dangerous rates of continuous global warming that would exceed the ability of a species to adapt through trait diffusion, and therefore lead to a collapse in the overall productivity of the species. As the rate of adaptation through intraspecies competition and genetic evolution decreases with species lifetime, we find critical rates of change that also depend fundamentally on lifetime. Dangerous rates of warming vary from 1°C per lifetime (at low trait diffusion rate) to 8°C per lifetime (at high trait diffusion rate). We conclude that rapid climate change is liable to favour short-lived organisms (e.g. microbes) rather than longer-lived organisms (e.g. trees).
... As a result, invasive species can provide useful case studies for understanding the roles of genetic differentiation and plasticity in the process of range expansion (Sexton et al. 2002;Parker et al. 2003;Molina- Montenegro et al. 2013). Studies of the response of invasive species to novel conditions may also shed light on how established species respond to novel environmental conditions, including climate change, through evolutionary and plastic responses (Moran and Alexander 2014;Chown et al. 2015;Hobbs et al. 2018). An important question in invasion biology is to what extent differentiation of local populations-in mean traits, plasticity or both-aids exotic invasive species in extending their distributions across varying environments, and how rapidly such differentiation occurs. ...
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Rapid local adaptation frequently occurs during the spread of invading species. It remains unclear, however, how consistent, and therefore potentially predictable, such patterns of local adaptation are. One approach to this question is to measure patterns of local differentiation in functional traits and plasticity levels in invasive species in multiple regions. Finding consistent patterns of local differentiation in replicate regions suggests that these patterns are adaptive. Further, this outcome indicates that the invading species likely responds predictably to selection along environmental gradients, even though standing genetic variation is likely to have been reduced during introduction. We studied local differentiation in the invasive annual plant Erodium cicutarium in two invaded regions, California and Chile. We collected seeds from across strong gradients in precipitation and temperature in Mediterranean-climate parts of the two regions (10 populations per region). We grew seeds from maternal families from these populations through two generations and exposed the second generation to contrasting levels of water and nutrient availability. We measured growth, flowering time and leaf functional traits across these treatments to obtain trait means and plasticity measures. We found strong differentiation among populations in all traits. Plants from drier environments flowered earlier, were less plastic in flowering time and reached greater size in all treatments. Correlations among traits within regions suggested a coordinated evolutionary response along environmental gradients associated with growing season length. There was little divergence in traits and trait intercorrelations between regions, but strongly parallel divergence in traits within regions. Similar, statistically consistent patterns of local trait differentiation across two regions suggest that local adaptation to environmental gradients has aided the spread of this invasive species, and that the formation of ecotypes in newly invaded environments has been relatively consistent and predictable.
... Novel assemblage structure tends to emerge as species move and change in abundance and dynamics in response to environmental change (Hobbs et al. 2018). The most obvious manifestation of this phenomenon in urban marine environments is among sessile assemblages on artificial shorelines. ...
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Human population density within 100 km of the sea is approximately three times higher than the global average. People in this zone are concentrated in coastal cities that are hubs for transport and trade – which transform the marine environment. Here, we review the impacts of three interacting drivers of marine urbanization (resource exploitation, pollution pathways and ocean sprawl) and discuss key characteristics that are symptomatic of urban marine ecosystems. Current evidence suggests these systems comprise spatially heterogeneous mosaics with respect to artificial structures, pollutants and community composition, while also undergoing biotic homogenization over time. Urban marine ecosystem dynamics are often influenced by several commonly observed patterns and processes, including the loss of foundation species, changes in biodiversity and productivity, and the establishment of novel assemblages, ruderal species and synanthropes. Further, we discuss potential urban acclimatization and adaptation among marine taxa, interactive effects of climate change and marine urbanization, and ecological engineering strategies for enhancing urban marine ecosystems. By assimilating research findings across disparate disciplines, we aim to build the groundwork for urban marine ecology – a nascent field; we also discuss research challenges and future directions for this new field as it advances and matures. Ultimately, all sides of coastal city design: architecture, urban planning, and civil and municipal engineering, will need to prioritize the marine environment if negative effects of urbanization are to be minimized. In particular, planning strategies that account for the interactive effects of urban drivers and accommodate complex system dynamics could enhance the ecological and human functions of future urban marine ecosystems. This article is protected by copyright. All rights reserved.
... In (e) the range remains the same in geographic extent, but the resources inside it vary. Figure modified fromHobbs et al. (2018). ...
Article
A species is not native outside its native range, but native range is not precisely defined. The invasion literature contains wide discussion of the core concepts such as naturalization, invasiveness, and ecological impact, but the concept of native range has received so little attention that a formal definition does not exist. I considered, among other impediments to a formal definition of native range, the sometimes arbitrariness of the spatial and temporal limits assigned to native range. Broad questions that remain include whether invasion theory can be used to define the native range for species without non-native ranges. © 2019 Society for Conservation Biology.
... Topography has strong effects on minimum air temperatures close to the ground, with cold air drainage often causing temperature inversions on floodplains and low-lying terraces, and in hollows (Bootsma, 1976;Kalma et al., 2012). The effect of leaf size on night-time chilling may thus help to explain the prevalence of small-leaved species on inland terraces and in frost hollows in New Zealand (Wardle, 1977;Lusk, 2014) and in south-eastern Australia (Hobbs et al., 2018). ...
Article
Explanations of leaf size variation commonly focus on water availability, yet leaf size also varies with latitude and elevation in environments where water is not strongly limiting. We provide the first conclusive test of a prediction of leaf energy balance theory that may explain this pattern: large leaves are more vulnerable to night‐time chilling, because their thick boundary layers impede convective exchange with the surrounding air. Seedlings of 15 New Zealand evergreens spanning 12‐fold variation in leaf width were exposed to clear night skies, and leaf temperatures were measured with thermocouples. We then used a global dataset to assess several climate variables as predictors of leaf size in forest assemblages. Leaf minus air temperature was strongly correlated with leaf width, ranging from −0.9 to −3.2°C in the smallest‐ and largest‐leaved species, respectively. Mean annual temperature and frost‐free period were good predictors of evergreen angiosperm leaf size in forest assemblages, but no climate variable predicted deciduous leaf size. Although winter deciduousness makes large leaves possible in strongly seasonal climates, large‐leaved evergreens are largely confined to frost‐free climates because of their susceptibility to radiative cooling. Evergreen leaf size data can therefore be used to enhance vegetation models, and to infer palaeotemperatures from fossil leaf assemblages.
... The contraction of species' geographic ranges is the result of population decline and local extinction, and a stark, prominent manifestation of adverse anthropogenic environmental change (Hobbs, Valentine, Standish, & Jackson, 2017). Range contractions are increasingly common across the globe (Thomas, Franco, & Hill, 2006)-for instance, 40% of 177 mammal species studied by Ceballos, Ehrlich, and Dirzo (2017) have experienced range contractions of >80%. ...
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Aim Species range contractions are increasingly common globally. The niche reduction hypothesis posits that geographic range contractions are often patterned across space owing to heterogeneity in threat impacts and tolerance. We applied the niche reduction hypothesis to the decline of a threatened marsupial predator across northern Australia, the northern quoll (Dasyurus hallucatus). Location Northern Australia. Methods We assembled a database containing 3,178 historic and contemporary records for northern quolls across the extent of their distribution dating between 1778 and 2019. Based on these records, we estimated changes in the geographic range of the northern quoll using α‐hulls across four main populations. We then examined how range contractions related to factors likely to mediate the exposure, susceptibility, or tolerance of northern quolls to threats. Result The extent of range contractions showed an east–west gradient, most likely reflecting the timing of spread of introduced cane toads (Rhinella marina). There were clear changes in environmental characteristics within the contemporary compared to the historic geographic range, with the most substantial occurring in populations that have suffered the greatest range contractions. The contemporary range is comprised of higher quality habitats (measured using environmental niche models), characterized by higher topographical ruggedness and annual rainfall, and reduced distance to water, compared to the historic range. Main conclusions Changes to range and niche likely reflect the capacity of complex habitats to ameliorate threats (namely predation and altered fire regimes), and access to resources that increase threat tolerance. This study highlights the multivariate nature of ecological refuges and the importance of high‐quality habitats for the persistence of species exposed to multiple threats. Our methods provide a useful framework which can be applied across taxa in providing valuable insight to management.
... Novel assemblage structure tends to emerge as species move and change in abundance and dynamics in response to environmental change (Hobbs et al. 2018). The most obvious manifestation of this phenomenon in urban marine environments is among sessile assemblages on artificial shorelines. ...
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Human population density within 100 km of the sea is approximately three times higher than the global average. People in this zone are concentrated in coastal cities that are hubs for transport and trade – which transform the marine environment. Here, we review the impacts of three interacting drivers of marine urbanization (resource exploitation, pollution pathways and ocean sprawl) and discuss key characteristics that are symptomatic of urban marine ecosystems. Current evidence suggests these systems comprise spatially heterogeneous mosaics with respect to artificial structures, pollutants and community composition, while also undergoing biotic homogenization over time. Urban marine ecosystem dynamics are often influenced by several commonly observed patterns and processes, including the loss of foundation species, changes in biodiversity and productivity, and the establishment of ruderal species, synanthropes and novel assemblages. We discuss potential urban acclimatization and adaptation among marine taxa, interactive effects of climate change and marine urbanization, and ecological engineering strategies for enhancing urban marine ecosystems. By assimilating research findings across disparate disciplines, we aim to build the groundwork for urban marine ecology – a nascent field; we also discuss research challenges and future directions for this new field as it advances and matures. Ultimately, all sides of coastal city design: architecture, urban planning and civil and municipal engineering, will need to prioritize the marine environment if negative effects of urbanization are to be minimized. In particular, planning strategies that account for the interactive effects of urban drivers and accommodate complex system dynamics could enhance the ecological and human functions of future urban marine ecosystems.
... Example 1: Environment of a resident species (a "stayer" according to Hobbs et al. 2018) prior to some major environmental change (e.g., draining of a wetland). ...
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Global change has complex eco-evolutionary consequences for organisms and ecosystems, but related concepts (e.g., novel ecosystems) do not cover their full range. Here we propose an umbrella concept of "ecological novelty" comprising (1) a site-specific and (2) an organism-centered, eco-evolutionary perspective. Under this umbrella, complementary options for studying and communicating effects of global change on organisms, ecosystems, and landscapes can be included in a toolbox. This allows researchers to address ecological novelty from different perspectives, e.g., by defining it based on (a) categorical or continuous measures, (b) reference conditions related to sites or organisms, and (c) types of human activities. We suggest striving for a descriptive, non-normative usage of the term "ecological novelty" in science. Normative evaluations and decisions about conservation policies or management are important, but require additional societal processes and engagement with multiple stakeholders.
... Example 1: Environment of a resident species (a "stayer" according to Hobbs et al. 2018) prior to some major environmental change (e.g., draining of a wetland). ...
Article
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Global change has complex eco-evolutionary consequences for organisms and ecosystems, but related concepts (e.g., novel ecosystems) do not cover their full range. Here we propose an umbrella concept of “ecological novelty” comprising (1) a site-specific and (2) an organismcentered, eco-evolutionary perspective. Under this umbrella, complementary options for studying and communicating effects of global change on organisms, ecosystems, and landscapes can be included in a toolbox. This allows researchers to address ecological novelty from different perspectives, e.g., by defining it based on (a) categorical or continuous measures, (b) reference conditions related to sites or organisms, and (c) types of human activities. We suggest striving for a descriptive, non-normative usage of the term “ecological novelty” in science. Normative evaluations and decisions about conservation policies or management are important, but require additional societal processes and engagement with multiple stakeholders.
... So, MPAs are commonly established based on their political and technical feasibility (Brooks, 2013) but also on this static -"snapshot" -basis that is, the current distribution of species and habitats. They do not consider the dynamics of species responses to climate change and potential distribution changes (i.e., range shift, contraction, or extension) (Araujo, Cabeza, Thuiller, Hannah, & Williams, 2004;Hannah, 2008;Hannah et al., 2007), resulting in new biotic assemblages and species interactions that will impact ecosystem functioning (Hobbs, Valentine, Standish, & Jackson, 2018). ...
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The Southern Ocean (SO) is among the regions on Earth that are undergoing regionally the fastest environmental changes. The unique ecological features of its marine life make it particularly vulnerable to the multiple effects of climate change. A network of Marine Protected Areas (MPAs) has started to be implemented in the SO to protect marine ecosystems. However, considering future predictions of the Intergovernmental Panel on Climate Change (IPCC), the relevance of current, static, MPAs may be questioned under future scenarios. In this context, the ecoregionalization approach can prove promising in identifying well‐delimited regions of common species composition and environmental settings. These so‐called ecoregions are expected to show similar biotic responses to environmental changes and can be used to define priority areas for the designation of new MPAs and the update of their current delimitation. In the present work, a benthic ecoregionalization of the entire SO is proposed for the first time based on abiotic environmental parameters and the distribution of echinoid fauna, a diversified and common member of Antarctic benthic ecosystems. A novel two‐step approach was developed combining species distribution modelling with Random Forest and Gaussian Mixture modelling from species probabilities to define current ecoregions and predict future ecoregions under IPCC scenarios RCP 4.5 and 8.5. The ecological representativity of current and proposed MPAs of the SO are discussed with regards to the modeled benthic ecoregions. Twelve benthic ecoregions were determined under Present conditions, they are representative of major biogeographic patterns already described. Our results show that the most dramatic changes can be expected along the Antarctic Peninsula, in East Antarctica and the sub‐Antarctic islands under both IPCC scenarios. Our results advocate for a dynamic definition of MPAs, they also argue for improving the representativity of Antarctic ecoregions in proposed MPAs and support current proposals of CCAMLR for the creation of Antarctic MPAs.
... Arrival can also occur through human-mediated actions, which can be deliberate (e.g., bringing in a NNS for biological control), or accidental (e.g., seeds, spores or organisms on clothing, equipment, or vehicles moved from one place to another). Such human-mediated transport has occurred throughout human history (Hobbs, Valentine, Standish, & Jackson, 2018;Hulme, 2009). Although there are multiple sources and multiple dispersal pathways for species invasions, only 5-20% of NNS are actually detrimental to ecosystems (McGeoch et al., 2016). ...
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Resources for biodiversity conservation are limited and it is therefore imperative that management actions that have the best chance of success are prioritized. Non-native species (NNS) are one of the key problems facing biodiversity conservation, so understanding how NNS disperse and establish can inform more effective conservation planning and management. Using a novel Bayesian belief network model, we investigated non-native plant dispersal on the approximately 550 islands along the Pilbara coast, Western Australia, and identified priority species and locations for targeted management. Of a total of around 9,000 weed arrivals onto the islands, 1,661 arrivals across 14 weed species had some probability of establishment. Suggested management actions in these cases would be education campaigns to inform visitors about the risk of accidental transport of propagules, quarantine programs, and eradication. For the seven weed species that arrived only via human dispersal and had a >10% chance of establishment on five islands, surveillance, and control of new arrivals would be the recommended management actions. Removal of propagule source populations would not be a cost-effective management strategy. The inherent flexibility of our model means that different objectives can be analyzed in a transparent way, making it a powerful tool for guiding effective targeted action, derived from an explicit decision-making framework. K E Y W O R D S Bayesian model, conservation management, island ecosystems, non-native plants, threatened species
... Assisted migration will be the only option for safeguarding some, if not many, species. Moreover, some species are naturally shifting their ranges, resulting in ecosystems and species assemblages changing regardless of whether or not we act (Hobbs et al. 2018). So how can the paradigm be changed to ensure assisted migration is trialed early, to increase the likelihood of success, rather than used as a last resort, when it may be too late for some populations? ...
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Species that cannot adapt or keep pace with a changing climate are likely to need human intervention to shift to more suitable climates. While hundreds of articles mention using translocation as a climate-change adaptation tool, in practice, assisted migration as a conservation action remains rare, especially for animals. This is likely due to concern over introducing species to places where they may become invasive. However, there are other barriers to consider, such as time-frame mismatch, sociopolitical, knowledge and uncertainty barriers to conservationists adopting assisted migration as a go-to strategy. We recommend the following to advance assisted migration as a conservation tool: attempt assisted migrations at small scales, translocate species with little invasion risk, adopt robust monitoring protocols that trigger an active response, and promote political and public support.
... Mobile and sedentary tendencies of organisms have been described as variation in personality (Funk 1955;Rasmussen and Belk 2012), a response to some environmental factor (Roy et al. 2012;Mossop et al. 2017), or as an interaction between intrinsic behavior and environmental variability (Rehage et al. 2016). The prevalence of mobile behavior types within a population is moderated by natural selection (Lowe and McPeek 2014); thus, it can be expected to change through time or vary among populations based on changing community structure or environmental conditions (Hobbs et al. 2017) in addition to varying among species (Funk 1955;Dewey 1981). ...
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Within many populations, some individuals may be more apt to move, and these individuals can substantially impact population dynamics. Invasive Silver Carp (Hypophthalmichthys molitrix) have spread throughout much of the Mississippi River Basin, and their presence has resulted in multiple negative ecosystem effects. Silver Carp are known to move hundreds of km, which has likely contributed to their rapid spread. Our study examined movement patterns and environmental cues for movement in Silver Carp based on acoustic telemetry of tagged fish that ranged widely (i.e., mobile) and those that did not range far from the site of their original capture and tagging (i.e., sedentary) in the Wabash River, USA. Sedentary and mobile designations were made based on observed extremes of mean annual ranges, and these designations were consistent within seasons and among years. Both movement groups displayed seasonal variation in movements, with mobile Silver Carp consistently moving greater distances within each season and sedentary Silver Carp exhibiting lower variability in distances moved than mobile individuals. Discharge (change in discharge) and temperature were significant predictors of mobile and sedentary individuals’ movements. Additional environmental variables (i.e., cumulative growing degree day, day of year, and change in temperature) also related to movement likelihood of sedentary individuals, whereas total length was the only additional variable that influenced movement likelihood of mobile individuals. Total length was significantly related to movement distance for both groups of Silver Carp, but the relationship was negative for sedentary fish and positive for mobile fish. Results point to differences in behavior that may require targeted management strategies to achieve agency goals to interrupt mobile individual movements that can result in range expansion. Such strategies may also limit introductions and invasions by other aquatic invasive species that exhibit similar behaviors.
... Another approach involves mapping features of climate change that are expected to lead to novel communities: the emergence of novel climate states and rapid climate changes (Ordonez et al. 2016, Burke et al. 2019. A fundamental scientific challenge is to continue developing ways to anticipate novel ecological communities composed of range-shifting native species or encroaching nonnative species (Chen et al. 2011, Hobbs et al. 2018, Wu et al. 2018). ...
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Earth is experiencing widespread ecological transformation in terrestrial, freshwater, and marine ecosystems that is attributable to directional environmental changes, especially intensifying climate change. To better steward ecosystems facing unprecedented and lasting change, a new management paradigm is forming, supported by a decision-oriented framework that presents three distinct management choices: resist, accept, or direct the ecological trajectory. To make these choices strategically, managers seek to understand the nature of the transformation that could occur if change is accepted while identifying opportunities to intervene to resist or direct change. In this article, we seek to inspire a research agenda for transformation science that is focused on ecological and social science and based on five central questions that align with the resist–accept–direct (RAD) framework. Development of transformation science is needed to apply the RAD framework and support natural resource management and conservation on our rapidly changing planet.
... No-analog communities include species that are extant today, yet they do not occur in the same combinations today as they did in the past (Williams & Jackson, 2007). No-analog communities are expected to increase as species reshuffling occurs in response to climatic and environmental changes (Hobbs et al., 2018;Williams & Jackson, 2007). Ecometrics provides a method for comparing noanalog communities with trait compositions within the modern trait bins of the ecometric spaces (Vermillion et al., 2018). ...
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Aim We investigate locomotor function in artiodactyls, represented by calcaneal gear ratio, as it relates to multiple environments. Using an ecometric approach, we develop a trait–environment model to investigate ecosystem‐level changes through time and to reconstruct past environments. We apply the trait–environment model to a case study of six sites in Kenya to evaluate changes over the past 100 years. Location Global. Methods Locomotor morphology was represented by calcaneal gear ratios measured as the overall length of a calcaneum divided by length of its in‐lever, that is calcaneal tuber. We collected calcaneal gear ratio measurements from skeletal specimens of 157 artiodactyl species in museum collections and used species’ spatial distributions to determine the composition of 47,420 communities globally. For 21,827 communities with three or more species of artiodactyls, we used maximum likelihood to model ecometric relationships between community‐level locomotor morphology and five environmental variables, including mean annual temperature, annual precipitation, elevation, vegetation cover and ecoregion province. Results Community mean gear ratios range from 1.43 to 1.56 (µ = 1.50). Mean gear ratios are highest in the tropical regions and lowest in the mid‐latitudes. Variance in mean calcaneal gear ratio is related to ecoregion division (68.6%), vegetation cover (63.5%) and precipitation (60.7%). In a case study of Kenyan sites, we demonstrate habitat homogenization patterns that match mammal community turnover patterns. Main conclusions With this ecometric framework, fossils of artiodactyl post‐crania can be used to assist in interpreting past ecoregion, vegetation cover and precipitation for a more comprehensive understanding of palaeoenvironment. These relationships between functional traits and environment will enable better models of biotic responses for conservation of functional diversity under changing environments.
... However, these benefits depend on the kind of forest transitions which occur [7,8]. In some regions, particularly on islands, where invasive species dominate successional pathways [9,10], forest transitions often lead to novel ecosystems [11][12][13]. Novel ecosystems generally have relatively low native biodiversity but still can provide important ecosystem services [14][15][16]. Conservation and community-based efforts increasingly seek to improve the ecosystem services provided by these non-native, secondary forests through ecological restoration and hybrid approaches using a mix of native and non-native economic, cultural, and/or agricultural species [16][17][18]. ...
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As the extent of secondary forests continues to expand throughout the tropics, there is a growing need to better understand the ecosystem services, including carbon (C) storage provided by these ecosystems. Despite their spatial extent, there are limited data on how the ecosystem services provided by secondary forest may be enhanced through the restoration of both ecological and agroecological functions in these systems. This study quantifies the above- and below-ground C stocks in a non-native secondary forest in Hawaiʻi where a community-based non-profit seeks to restore a multi-strata agroforestry system for cultural and ecological benefits. For soil C, we use the equivalent soil mass method both to estimate stocks and examine spatial heterogeneity at high resolution (eg. sub 5 m) to define a method and sampling design that can be replicated to track changes in C stocks on-site and elsewhere. The assessed total ecosystem C was ~388.5 Mg C/ha. Carbon stock was highest in trees (~192.4 Mg C/ha; ~50% of total C); followed by soil (~136.4 Mg C/ha; ~35% of total C); roots (~52.7 Mg C/ha; ~14% of total C); and was lowest in coarse woody debris (~4.7 Mg C/ha; ~1% of total C) and litter (~2.3 Mg C/ha; <1% of total C). This work provides a baseline carbon assessment prior to agroforest restoration that will help to better quantify the contributions of secondary forest transitions and restoration efforts to state climate policy. In addition to the role of C sequestration in climate mitigation, we also highlight soil C as a critical metric of hybrid, people-centered restoration success given the role of soil organic matter in the production of a suite of on- and off-site ecosystem services closely linked to local sustainable development goals.
... These findings can be explained by reduced habitat structure, food resources and microclimatic range in cultivated farmlands (Andersen, 1995;Ekroos et al., 2010;Ng et al., 2018a, b;Pereyra et al., 2019;Yates et al., 2012), and the biotic influence of a dominant ant species in remnant patches (Greenslade, 1976). Removal and modification of native vegetation are the primary drivers of the loss of many insect species Hobbs et al., 2018). Finding a combination of significant differences in community dispersion within groups (transect-habitat pairs), as well as spatial turnover and convergence in community composition, suggests homogenisation of ant assemblages in cultivated farmlands with more generalist species such as strong dispersers and disturbance-tolerant species becoming more common (McKinney and Lockwood, 1999). ...
Article
Recent alarming losses of insects from agricultural landscapes in multiple countries around the world have brought into sharp focus the urgent need to identify ways to manage these landscapes to avoid further biodiversity decline. Identifying the drivers of insect declines, such as land use change, is critical to this effort. We examined ant communities at the interface between remnant vegetation patches and three adjoining farmland types (wheat crop, rested from cropping and restoration plantings) in a fragmented landscape in temperate Australia. We asked: do ant communities and occurrence of individual species differ between remnant patches and farmlands with more intensive farmland use (restoration plantings < rested farmlands < wheat crop)? We recorded 13,283 ants belonging to 102 species from 30 genera. Excluding 21 singletons, 27 species only occurred in remnant patches compared to ten species found only in farmlands. Ant community composition in wheat crop and rested farmlands significantly differed from their adjacent remnant patches and were more homogeneous. In contrast, ant communities from restoration plantings in farmland were not significantly different in composition from those in the adjacent remnant patch. The large, aggressive Australian meat ant (Iridomyrmex purpureus) showed significantly higher occurrence in the remnant patch than all farmland types, and we suggest that the absence of this strongly interacting species from farmlands may have contributed to biotic homogenisation. Our findings show that native vegetation provides crucial habitat resources for many ant species that are not provided by farmlands, and native plantings can, in some cases, ameliorate negative effects of farmland clearing over relatively short time scales (<7 years). Agricultural intensification that involves loss of remnant native vegetation or reduced revegetation will contribute to ongoing losses and changes to ant biodiversity in farming landscapes. However, replanting native vegetation can lead to rapid restoration, signifying a possible simple remedy to insect declines.
... Furthermore, although species occurrence data are from distribution estimates updated in 2007 (Patterson et al., 2007), precipitation is an average of data from 1970 to 2000 (Fick & Hijmans, 2017). This temporal mismatch may introduce a bias as faunal assemblages are increasingly affected by anthropogenic pressures, such as land use and habitat loss (Hobbs et al., 2018;Lyons et al., 2016). For example, a current species range map may no longer capture precipitation regime from 1970 to 2000, but may be a reflection of distribution constraints, such as habitat loss and competition from invasive or introduced species. ...
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• Ecometrics is the study of community‐level functional trait–environment relationships. We use ecometric analyses to estimate paleoenvironment and to investigate community‐level functional changes through time. • We evaluate four methods that have been used or have the potential to be used in ecometric analyses for estimating paleoenvironment to determine whether there have been systematic differences in paleoenvironmental estimation due to choice of the estimation method. Specifically, we evaluated linear regression, polynomial regression, nearest neighbor, and maximum‐likelihood methods to explore the predictive ability of the relationship for a well‐known ecometric dataset of mammalian herbivore hypsodonty metrics (molar tooth crown to root height ratio) and annual precipitation. Each method was applied to 43 Pleistocene fossil sites and compared to annual precipitation from global climate models. Sites were categorized as glacial or interglacial, and paleoprecipitation estimates were compared to the appropriate model. • Estimation methods produce results that are highly correlated with log precipitation and estimates from the other methods (p < 0.001). Differences between estimated precipitation and observed precipitation are not significantly different across the four methods, but maximum likelihood produces the most accurate estimates of precipitation. When applied to paleontological sites, paleoprecipitation estimates align more closely with glacial global climate models than with interglacial models regardless of the age of the site. • Each method has constraints that are important to consider when designing ecometric analyses to avoid misinterpretations when ecometric relationships are applied to the paleontological record. We show interglacial fauna estimates of paleoprecipitation more closely match glacial global climate models. This is likely because of the anthropogenic effects on community reassembly in the Holocene.
... Differences in co-occurring species' abilities to pass through new ecological filters can result in the formation of novel assemblages (Huntley 1991, Hobbs et al. 2018. For example, novel assemblages of small mammals were observed after differential species' range shifts in response to climate change in Yosemite National Park, where closely related species responded idiosyncratically to climate change (Moritz et al. 2008). ...
Article
Ecotones are responsive to environmental change and pave a path for succession as they move across the landscape. We investigated the biotic and abiotic filters to species establishment on opposite ends of a tidal marsh-forest ecotone that is moving inland in response to sea level rise. We transplanted four plant species common to the ecotone to the leading or trailing edge of the migrating ecotone, with and without caging to protect them from ungulate herbivores. We found that species exhibited an individualistic response to abiotic and biotic pressures in this ecotone; three species performed better at the leading edge of the ecotone in the coastal forest, whereas one performed better at the trailing edge in the marsh. Specifically, grass species Phragmites australis and Panicum virgatum grew more in the low light and low salinity conditions of the leading edge of the ecotone (forest), whereas the shrub Iva frutescens grew better in the high light, high salinity conditions of the trailing edge of the ecotone (marsh). Furthermore, of the four species, only P. australis was affected by the biotic pressure of herbivory by an introduced ungulate, Cervus nippon, which greatly reduced its biomass and survival at the leading edge (forest). P. australis is an aggressive invasive species and has been observed to dominate in the wake of migrating marsh-forest ecotones. Our findings detail the role of lower salinity stress to promote and herbivory pressure to inhibit the establishment of P. australis during shifts of this ecotone, and also highlight an interaction between two non-native species, P. australis and C. nippon. Understanding migration of the marsh-forest ecotone and the factors controlling P. australis establishment are critical for marsh conservation in the face of sea level rise. More generally, our findings support the conclusion that the abiotic and biotic filters of a migrating ecotone shape the resulting community.
... In coastal areas where construction is taking place, latitude is arguably the dominant proxy for a suite of environmental conditions. However, pressures from climate change are rapidly rearranging the global distribution of life (Hobbs et al. 2018). Whereas the effects of climate change are variable by region, the impacts are likely to vary with latitude. ...
Article
Coastal ecosystems are under growing pressure from human activities such as pollution and climate change. Although the rapidly growing numbers of humans living in coastal areas is a large part of the problem, there is great opportunity to improve the resistance and resilience of biotic communities via creative changes to the engineering design of built infrastructure. Here, we apply ecological theories to create a framework for adaptive building in marine systems that can be applied by managers worldwide. We explain how climate effects could be mitigated across different spatial scales with both physical and biological interventions. This requires an approach based on ecological theory that incorporates our understanding of how systems withstand (resistance) or recover (resilience) from impacts and takes into account future local and global environmental conditions. By translating ecological theory into practical application, we propose a framework for the choice and design of coastal infrastructure that can underpin effective, forward-looking conservation strategies.
... Key factors driving novel community emergence include the rapid pace of global climate change (6)(7)(8) , breakdown of biogeographic barriers, species invasions and habitat degradation (9)(10)(11) . These factors result in novel environments, 35 new species combinations, and altered ecosystem functions (12) . Little research has focused on the demographic drivers both during the transition to novel communities, and in subsequent time periods after they develop. ...
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Local and global environmental change is transforming ecological assemblages into new configurations, resulting in ecosystems with novel communities. Here we develop a robust methodology for the identification of novel communities, examine patterns in their natural chance of occurrence, and quantify the probability of local extinction, emigration, local origination and immigration in transitions to and from novel communities. Using a global dataset of Cenozoic marine plankton communities, we found the probability of local extinction, origination and emigration during transitions to a novel community increased up to four times that of background community changes, with the probability of species loss about equal to that of species gain. Although rare, once a novel community state emerged, the chance of shifting into another novel community state was five times greater than expected by chance. Thus, for marine planktonic communities at 100K year time scales, novel communities are particularly sensitive to further extinctions and community shift. One Sentence Summary Once developed, novel ecological communities face increased susceptibility to further shifts in species composition, with heightened extinction risk.
... In (e) the range remains the same in geographic extent, but the resources inside it vary. Figure modified fromHobbs et al. (2018). ...
... Valuing populations only within historic ranges offers but one perspective on how to protect Earth's diversity (Davis et al. 2011). Broadening our view of nature illuminates processes that enable wildlife to adapt to the Anthropocene (Hobbs et al. 2017). Protecting megafauna in their introduced range can supplement rather than supplant existing conservation efforts. ...
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Article impact statement: Incorporating introduced populations into the moral universe of conservation shows the Anthropocene is astoundingly rich in megafaun.
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Environmental change is transforming ecological assemblages into new configurations, resulting in novel communities. We developed a robust methodology to detect novel communities, examine patterns of emergence, and quantify probabilities of local demographic turnover in transitions to and from novel communities. Using a global dataset of Cenozoic marine plankton communities, we found that the probability of local extinction, origination, and emigration during transitions to a novel community increased two to four times that of background community changes. Although rare, novel communities were five times more likely than chance to shift into another novel state. For marine plankton communities at a 100,000-year time grain, novel communities were sensitive to further extinctions and substantial community change.
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During the Anthropocene, ongoing rapid environmental changes are exposing many species to novel resources. However, scientists’ understanding of what novel resources are and how they impact species is still rudimentary. Here, we used a resource‐based approach to explore novel resources. First, we conceptualized novel resource use by species along two dimensions of novelty: namely, ecosystem novelty and resource novelty. We then examined characteristics that influence a species’ response to a novel resource and how novel resources can affect individuals, populations, species, and communities. In addition, we discuss potential management complications associated with novel resource use by threatened species. As conservation and management embrace global environmental change, it is critical that ecologists improve the current understanding of the opportunities and risks that novel resources present to species conservation.
Article
Purpose Human actions on natural ecosystems have not only jeopardized human well-being but also threatened the existence of other species. On the other hand, the benefits resulting from a greater integration between the logic of nature and human occupations have been seen as motivating factors for the prevention and mitigation of environmental impacts in landscape planning, since it provides human well-being through the grant of resources, regulation of the environment and socio-cultural services called ecosystem services. This article highlights the relevance of using ecosystem integrity indicators related to the functioning of ecological support processes for landscape planning. Design/methodology/approach The research used the photosynthetic performance of vegetation through carbon fluxes in the landscape, defining areas where different approaches to green infrastructure can be applied, gaining over the majority of work in this area, in which low degrees of objectivity on measurement and consequent ecological recovery still prevail. Thus, using the conceptual support of restoration ecology and remote sensing, the work identified different vegetation performances in relation to the supporting ecological processes using the multispectral CO 2 flux index, linked to the carbon flux to identify the photosynthetic effectiveness of the vegetation and the Topographic Wetness Index (TWI). Findings With a study in the Distrito Federal (DF), the results of the different performances of vegetation for ecological support, through electromagnetic signatures and associated vegetation formations, allowed for the identification of hotspots of greater integrity that indicate multifunctional areas to be preserved and critical areas that deserve planning actions using green infrastructure techniques for their restoration and integration into the landscape. Originality/value This approach could be the initial step towards establishing clear and assertive criteria for selecting areas with greater potential for the development of supporting ecological processes in the territorial mosaic.
Book
Cambridge Core - Natural Resource Management, Agriculture, Horticulture and forestry - Rewilding - edited by Nathalie Pettorelli
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Professor Richard Hobbs has had a profound influence on the development of the discipline of restoration ecology. With more than 300 publications spanning a broad scope of applied ecological sciences, he has collaborated with hundreds of researchers. His sometimes‐provocative insights, balanced by extensive empirical research, will have a lasting impact by encouraging people to think more broadly about the science and practice of ecological restoration. Here, on the eve of his retirement, some of his staff and students, past and present, take a retrospective look at his contributions to restoration ecology both as a scientist and as a mentor. This article is protected by copyright. All rights reserved.
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Restoration has long used the reference concept as a cornerstone in setting targets, designing interventions, and benchmarking success. Following the initial applications of restoration references, however, the definition and broader relevance has been debated. Particularly in an era of directional global change, using historic or even contemporary ecosystem models has been contentious among restoration scientists and practitioners. In response, there have been calls for increasing flexibility in how references are defined and diversifying sources of data used to describe a reference. Previous frameworks suggest reference information can be drawn from sources across two main axes of time and space, covering historic to contemporary sources, and near to far spatial scales. We extend these axes by including future projections of climate and species composition and regional ecological information that is spatially disconnected from defined ecosystem types. Using this new framework, we conducted a review of restoration literature published between 2010-2020, extracting the temporal and spatial scales of reference data and classifying reference metrics by data type. The studies overwhelmingly focused on contemporary, ecosystem-specific references to benchmark a completed project's success. The most commonly reported reference metrics were plant-based, and contemporary reference data sources were more diverse than historical or future reference data. As global conditions continue to shift, we suggest that restoration projects would benefit by expanding reference site information to include forecasted and spatially diverse data. A greater diversity of data sources can enable higher flexibility and long-term restoration success in the face of global change. This article is protected by copyright. All rights reserved.
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As temperatures continue rising, the direction, magnitude, and tempo of change in disturbance‐prone forests remain unresolved. Even forests long resilient to stand‐replacing fire face uncertain futures, and efforts to project changes in forest structure and composition are sorely needed to anticipate future forest trajectories. We simulated fire (incorporating fuels feedbacks) and forest dynamics on five landscapes spanning the Greater Yellowstone Ecosystem (GYE) to ask: (1) How and where are forest landscapes likely to change with 21st‐century warming and fire activity? (2) Are future forest changes gradual or abrupt, and do forest attributes change synchronously or sequentially? (3) Can forest declines be averted by mid‐21st‐century stabilization of atmospheric greenhouse gas (GHG) concentrations? We used the spatially explicit individual‐based forest model iLand to track multiple attributes (forest extent, stand age, tree density, basal area, aboveground carbon stocks, dominant forest types, species occupancy) through 2100 for six climate scenarios. Hot‐dry climate scenarios led to more fire, but stand‐replacing fire peaked in mid‐century and then declined even as annual area burned continued to rise. Where forest cover persisted, previously dense forests were converted to sparse young woodlands. Increased aridity and fire drove a ratchet of successive abrupt declines (i.e., multiple annual landscape‐level changes ≥ 20%) in tree density, basal area and extent of older (>150 yr) forests, whereas declines in carbon stocks and mean stand age were always gradual. Forest changes were asynchronous across landscapes, but declines in stand structure always preceded reductions in forest extent and carbon stocks. Forest decline was most likely in less topographically complex landscapes dominated by fire‐sensitive tree species (Picea engelmannii, Abies lasiocarpa, Pinus contorta var. latifolia) and where fire resisters (Pseudotsuga menziesii var. glauca) were not already prevalent. If current GHG emissions continue unabated (RCP 8.5) and aridity increases, a suite of forest changes would transform the GYE, with cascading effects on biodiversity and myriad ecosystem services. However, stabilizing GHG concentrations by mid‐century (RCP 4.5) would slow the ratchet, moderating fire activity and dampening the magnitude and rate of forest change. Monitoring changes in forest structure may serve as an operational early warning indicator of impending forest decline.
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Quaternary (last 2.6 million years) botany involves studying plant megafossils (e.g. tree stumps), macrofossils (e.g. seeds, leaves), and microfossils (e.g. pollen, spores) preserved in peat bogs and lake sediments. Although megafossils and macrofossils have been studied since the late eighteenth century, Quaternary botany today is largely dominated by pollen analysis. Quaternary pollen analysis is just over 100 years old. It started primarily as a geological tool for correlation, relative dating, and climate reconstruction. In 1950 a major advance occurred with the publication by Knut Fægri and Johs Iversen of their Text-book of Modern Pollen Analysis which provided the foundations for pollen analysis as a botanical and ecological tool for studying past dynamics of biota and biotic systems. The development of radiocarbon dating in the 1950s freed pollen analysis from being a tool for relative dating. As a result of these developments, pollen analysis became a valuable implement in long-term ecology and biogeography. Selected contributions that Quaternary botany has made to ecology and biogeography since 1950 are reviewed. They fall into four general parts: (1) ecological aspects of interglacial and glacial stages such as location and nature of glacial-stage tree refugia and long-term soil development in glaciated and unglaciated areas; (2) biotic responses to Quaternary environmental change (spreading, extinction, persistence, adaptation); (3) ecological topics such as potential niches, the nature of vegetation, and tree and forest dynamics; and (4) its application to ecological topics such as human impact in tropical systems, conservation in a changing world, island palaeoecology, plant–animal interactions, and biodiversity patterns in time. The future of Quaternary botany is briefly discussed and 10 suggestions are presented to help strengthen it and its links with ecology and biogeography. Quaternary botany has much to contribute to ecology and biogeography when used in conjunction with new approaches such as ancient-DNA, molecular biomarkers, and multi-proxy palaeoecology.
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For marine ectotherms, larval success, planktonic larval duration and dispersal trajectories are strongly influenced by temperature, and therefore ocean warming and heatwaves have profound impacts on these sensitive stages. Warming, through increased poleward flow in regions with western boundary currents, such as the East Australia Current (EAC), provides opportunities for range extension as propagules track preferred conditions. Two sea urchin species, Centrostephanus rodgersii and Heliocidaris tuberculata, sympatric in the EAC warming hotspot, exhibit contrasting responses to warming. Over half a century, C. rodgersii has undergone marked poleward range extension, but the range of H. tuberculata has not changed. We constructed thermal performance curves (TPC) to determine if contrasting developmental thermal tolerance can explain this difference. The temperatures tested encompassed present-day distribution and forecast ocean warming/heatwave conditions. The broad and narrow thermal optimum (Topt) ranges for C. rodgersii and H. tuberculata larvae (7.2 °C and 4.7 °C range, respectively) matched their realised (adult distribution) thermal niches. The cool and warm temperatures for 50% development to the feeding larva approximated temperatures at adult poleward range limits. Larval cool tolerances with respect to mean local temperature differed, 6.0 °C and 3.8 °C, respectively. Larval warm tolerances were similar for both species as are the adult warm range edges. The larvae of both species would be sensitive to heatwaves. Centrostephanus rodgersii has stayed in place and shifted in space, likely due to its broad cold-warm larval thermal tolerance and large thermal safety margins. Phenotypic plasticity of the planktonic stage of C. rodgersii facilitated its range extension. In contrast, larval cold intolerance of H. tuberculata explains its restricted range and will delay poleward extension as the region warms. In a warming ocean we show that intrinsic thermal biology traits of the pelagic stage provide an integrative tool to explain species-specific variation in range shift patterns.
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Translocation is a widely used conservation tool for reintroducing, introducing or restocking wildlife for conservation purposes. Disease and parasites are often unintended hitchhikers during translocations. Conservation managers have begun considering the health, disease risk and parasite loads of their species post‐translocation, but not often during the translocation itself. When parasites and diseases are considered during the translocation, they are often dealt with via medical interventions resulting in the complete eradication of parasites leaving the host vulnerable to new or novel disease or parasite loads, or disrupting specialised host–parasite interactions or disease dynamics. To determine the extent of consideration and intervention of parasites and diseases in the Australian context, we conducted an aggregate scoping review of wildlife conservation translocations resulting in 98 identified translocations of 61 species with most (75%) being translocations of 40 species of mammals. Of the 98 translocations identified, only 40 (41%) described any management actions to monitor the health or disease of the translocation, such as health checks, post‐mortems or sampling of disease or parasite fauna. Surprisingly, some literature mentioned specific diseases or parasites impacting a population (29% of 90 translocations), but only 16 (16%) undertook intervention to prevent these further spreading. When considering general trends over time, more translocations are considering parasites and disease in their planning, and some management action is usually taken; however, medical intervention remains low. In order to ensure that parasites and diseases are part of conservation thinking, we provide a flowchart for managers that can be implemented into future translocations that consider both the negative consequences of disease and parasites, and the ecological necessity and potential benefits of retaining co‐evolved parasites and diseases.
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The 2011 East Japan earthquake generated a massive tsunami that launched an extraordinary transoceanic biological rafting event with no known historical precedent. We document 289 living Japanese coastal marine species from 16 phyla transported over 6 years on objects that traveled thousands of kilometers across the Pacific Ocean to the shores of North America and Hawai‘i. Most of this dispersal occurred on nonbiodegradable objects, resulting in the longest documented transoceanic survival and dispersal of coastal species by rafting. Expanding shoreline infrastructure has increased global sources of plastic materials available for biotic colonization and also interacts with climate change–induced storms of increasing severity to eject debris into the oceans. In turn, increased ocean rafting may intensify species invasions.
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Of the primary responses to contemporary climate change – “move, adapt, acclimate, or die” – that are available to organisms, “acclimate” may be effectively achieved through behavioral modification. Behavioral flexibility allows animals to rapidly cope with changing environmental conditions, and behavior represents an important component of a species’ adaptive capacity in the face of climate change. However, there is currently a lack of knowledge about the limits or constraints on behavioral responses to changing conditions. Here, we characterize the contexts in which organisms respond to climate variability through behavior. First, we quantify patterns in behavioral responses across taxa with respect to timescales, climatic stimuli, life-history traits, and ecology. Next, we identify existing knowledge gaps, research biases, and other challenges. Finally, we discuss how conservation practitioners and resource managers can incorporate an improved understanding of behavioral flexibility into natural resource management and policy decisions.
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Warming-induced range shifts along elevational and latitudinal gradients have been observed in several species from various taxa. The mobility and behavioral plasticity of large endothermic mammals, however, complicate the detection of climatic effects on their spatial distributions. Here, we analyzed 230,565 hunting locations of the four most abundant ungulate species in the European Alps: ibex, chamois, red deer, and roe deer. Year-to-year and inter-decadal range shifts toward higher elevations in Switzerland coincided with warmer, snow-free, and thus more favorable autumn conditions in the same area. The average harvest elevation of ibex, chamois, and red deer significantly increased between 1991 and 2013. Although this trend is anticipated to continue, behavioral plasticity may allow the Alpine ibex and other mountain ungulates to buffer some of the associated consequences of climate change. Our results demonstrate the utility of well-replicated hunting archives to supplement shorter but more precise monitoring data. This study also provides independent evidence of animal range shifts in response to environmental change at interannual and multi-decadal time-scales.
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Distributions of Earth’s species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to global scales affects ecosystem functioning, human well-being, and the dynamics of climate change itself. Production of natural resources required for food security, patterns of disease transmission, and processes of carbon sequestration are all altered by changes in species distribution. Consideration of these effects of biodiversity redistribution is critical yet lacking in most mitigation and adaptation strategies, including the United Nation’s Sustainable Development Goals.
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Current systems of conservation reserves may be insufficient to sustain biodiversity in the face of climate change and habitat losses. Faced with these pressures, calls have been made to protect the Earth's remaining wildlands and complete the system of protected areas by establishing conservation reserves that (i) better represent ecosystems; (ii) increase connectivity to facilitate biota movement in response to stressors including climate change; and (iii) promote species persistence within intact landscapes. Using geospatial data, we conducted an assessment for expanding protected areas within the contiguous U.S. to include the least human-modified wildlands, establish a connected network, and better represent ecosystem diversity and hotspots of biodiversity. Our composite map highlights areas of high value to achieve goals in the western U.S., where existing protected areas and lands with high ecological integrity are concentrated. We identified important areas in the East rich in species and contain ecosystems that are poorly represented in the existing protected area system. Expanding protection to these priority areas is ultimately expected to create a more resilient system for protecting the nation's biological heritage. This expectation should be subject to rigorous testing prior to implementation, and regional monitoring will ensure areas and actions are adjusted over time. This article is protected by copyright. All rights reserved.
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BACKGROUND: The pace and magnitude of human-caused global change has accelerated dramatically over the past 50 years, overwhelming the capacity of many ecosystems and species to maintain themselves as they have under the more stable conditions that prevailed for at least 11,000 years. The next few decades threaten even more rapid transformations because by 2050, the human population is projected to grow by 3 billion while simultaneously increasing per capita consumption. Thus, to avoid losing many species and the crucial aspects of ecosystems that we need—for both our physical and emotional well-being—new conservation paradigms and integration of information from conservation biology, paleobiology, and the Earth sciences are required.
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Invasion of riparian habitats by non-native plants is a global problem that requires an understanding of community-level responses by native plants and animals. In the Great Plains, resource managers have initiated efforts to control the eastward incursion of Tamarix as a non-native bottomland plant (Tamarix ramosissima) along the Cimarron River in southwestern Kansas, United States. To understand how native avifauna interact with non-native plants, we studied the effects of Tamarix removal on riparian bird communities. We compared avian site occupancy of three foraging guilds, abundance of four nesting guilds, and assessed community dynamics with dynamic, multiseason occupancy models across three replicated treatments. Community parameters were estimated for Tamarix-dominated sites (untreated), Tamarix-removal sites (treated), and reference sites with native cottonwood sites (Populus deltoides). Estimates of initial occupancy (ψ2006) for the ground-to-shrub foraging guild tended to be highest at Tamarix-dominated sites, while initial occupancy of the upper-canopy foraging and mid-canopy foraging guilds were highest in the treated and reference sites, respectively. Estimates of relative abundance for four nesting guilds indicated that the reference habitat supported the highest relative abundance of birds overall, although the untreated habitat had higher abundance of shrub-nesters than treated or reference habitats. Riparian sites where invasive Tamarix is dominant in the Great Plains can provide nesting habitat for some native bird species, with avian abundance and diversity that are comparable to remnant riparian sites with native vegetation. Moreover, presence of some native vegetation in Tamarix-dominated and Tamarix-removal sites may increase abundance of riparian birds such as cavity-nesters. Overall, our study demonstrates that Tamarix may substitute for native flora in providing nesting habitat for riparian birds at the eastern edge of its North American range.
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How do organisms arrive on isolated islands, and how do insular evolutionary radiations arise? In a recent paper, Wilmé et al. (2016a) argue that early Austronesians that colonized Madagascar from Southeast Asia translocated giant tortoises to islands in the western Indian Ocean. In the Mascarene Islands, moreover, the human-translocated tortoises then evolved and radiated in an endemic genus (Cylindraspis). Their proposal ignores the broad, established understanding of the processes leading to the formation of native island biotas, including endemic radiations. We find Wilmé et al.'s suggestion poorly conceived, using a flawed methodology and missing two critical pieces of information: the timing and the specifics of proposed translocations. In response, we here summarize the arguments that could be used to defend the natural origin not only of Indian Ocean giant tortoises but also of scores of insular endemic radiations world-wide. Reinforcing a generalist's objection, the phylogenetic and ecological data on giant tortoises, and current knowledge of environmental and palaeogeographical history of the Indian Ocean, make Wilmé et al.'s argument even more unlikely.
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Evidence from DNA phylogeny, Plio-Pleis-tocene ocean currents, giant tortoise dispersal , evolution of plant defences, radiocarbon dates and archaeology indicates that the endemic giant tortoises on the Mascarenes and Seychelles colonized naturally and were not translocated there by humans.
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Conservation triage seems to be at a stalemate between those who accept triage based on utilitarian rationalization, and those that reject it based on a number of ethical principles. We argue that without considered attention to the ethics of conservation triage we risk further polarization in the field of conservation. We draw lessons from the medical sector, where triage is more intuitive and acceptable, and also from disaster planning, to help navigate the challenges that triage entails for conservation science, practice, and policy. We clarify the consequentialist, deontological, and virtue ethical stances that influence the level of acceptance of triage. We emphasize the ethical dimensions of conservation triage in principle and in practice, particularly in the context of stakeholder diversity, a wide range of possible objectives and actions, broader institutions, and significant uncertainties. A focus on a more diverse set of ethics, more considered choice of triage as a conservation tool, open communication of triage objectives, and protocols, greater consideration of risk preferences, and regular review and adaptation of triage protocols is required for conservation triage to become more acceptable among diverse conservation practitioners, institutions, and the general public. Accepting conservation triage as fundamentally an ethical problem would foster more open dialog and constructive debate about the role of conservation triage in a wider system of care.
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In a recent Discussion Paper, Hoffmann and Courchamp (2016) posed the question: are biological invasions and natural colonisations that different? This apparently simple question resonates at the core of the biological study of human-induced global change, and we strongly believe that the answer is yes: biological invasions and natural colonisations differ in processes and mechanisms in ways that are crucial for science, management, and policy. Invasion biology has, over time, developed into the broader transdisciplinary field of invasion science. At the heart of invasion science is the realisation that biological invasions are not just a biological phenomenon: the human dimension of invasions is a fundamental component in the social-ecological systems in which invasions need to be understood and managed.
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The Gondwana Link (GL) program spans some 1,000km and includes organizations, businesses, and individuals working to improve ecological function across the most intact large areas of habitat remaining in southwestern Australia (SWA). Noncompetitive leadership plus a focus on tangible achievement have been critical to providing the cohesion and initial momentum needed to support and inspire increased effort from those involved. Ongoing success rests on the responses of people working together, having respect for the integrity of the collective effort and for the specific roles of others across differing but complementary roles. Significant achievements have been secured, with progress in scientific knowledge generally following initial implementation of key actions. Lasting improvements in ecological health and resilience will only occur through larger-scale actions, which require more effort and time. The GL program has been an important initiative in strengthening the awareness of the distinctive ecological systems across SWA and the intertwined characteristics of resilience and fragility that characterize the region and its people. It has also had a role in inspiring and informing growth in large-scale connectivity programs nationally and internationally.
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Community-level models (CLMs) aim to improve species distribution modeling (SDM) methods by attempting to explicitly incorporate the influences of interacting species. However, the ability of CLMs to appropriately account for biotic interactions is unclear. We applied CLM and SDM methods to predict the distributions of three dominant conifer tree species in the U.S. Rocky Mountains and compared CLM and SDM predictive accuracy as well as the ability of each approach to accurately reproduce species co-occurrence patterns. We specifically evaluated the performance of two statistical algorithms, MARS and CForest, within both CLM and SDM frameworks. Across all species, differences in SDM and CLM predictive accuracy were slight and can be attributed to differences in model structure rather than accounting for the effects of biotic interactions. In addition, CLMs generally over-predicted species co-occurrence, while SDMs under-predicted co-occurrence. Our results demonstrate no real improvement in the ability of CLMs to account for biotic interactions relative to SDMs. We conclude that alternative modeling approaches are needed in order to accurately account for the effects of biotic interactions on species distributions.
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We argue that human-mediated invasions are part of the spectrum of species movements, not a unique phenomenon, because species self-dispersing into novel environments are subject to the same barriers of survival, reproduction, dispersal and further range expansion as those assisted by people. Species changing their distributions by human-mediated and non-human mediated modes should be of identical scientific interest to invasion ecology and ecology. Distinctions between human-mediated invasions and natural colonisations are very valid for management and policy, but we argue that these are value-laden distinctions and not necessarily an appropriate division for science, which instead should focus on distinctions based on processes and mechanisms. We propose an all-encompassing framework of species range expansion. This does not detract from the importance of invasion biology as a discipline, but instead will help bring together research being conducted on multiple taxa, and by multiple disciplines, including epidemiology, that are often focused on an identical phenomenon: colonisation.
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The management of harmful non-native species is a priority for governments worldwide. However, confusion concerning what constitutes a ‘native’ species has led to ambiguous or even contradictory wording in adopted legislation. A key issue concerns the treatment of species dispersing beyond their normal ranges in response to global change. Range-expanding species can have negative impacts on the ecosystems they colonize, prompting some authorities to class them as ‘non-natives’. However, range-shifts are becoming increasingly necessary for species persistence in response to climate and habitat change. Distinguishing these ‘desirable’ range-shifts from other human-driven introductions is therefore a core requirement of legislation. Here, we propose a simplified framework that can be applied unambiguously across the policy arena. We suggest that the ‘non-native’ moniker should apply exclusively to species transported outside their native range by direct transport (defined herein), leaving species moving via unassisted dispersal as ‘natives’, even if they are responding indirectly to anthropogenic change. We believe that widespread adoption of this simplified approach will facilitate more consistent multinational policies to target problematic invasive species.
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Giant tortoises are known from several remote islands in the Indian Ocean (IO). Our present understanding of ocean circulation patterns, the age of the islands, and the life history traits of giant tortoises makes it difficult to comprehend how these animals arrived on such small, remote and geologically young (8–1.5 Ma) landmasses. For colonization to have occurred by dispersal, giant tortoises must either have originated in Madagascar or Africa and swum for hundreds of km against the ocean currents, or have launched themselves from the eastern IO margin and drifted with the currents over several thousands of km of open ocean. After these navigational feats, the tortoises would have needed to found new, viable populations on potentially inhospitable volcanic or coral outcrops. Geologically recent sea level changes are likely to have eliminated terrestrial life from islands like Aldabra, complicating the scenario. We reviewed information relating to IO geology, the evolution and ecology of giant tortoises, and the spread of humans within the region, and propose an alternative explanation: we posit that giant tortoises were introduced to the IO islands by early Austronesian sailors, possibly to establish provisioning stations for their journeys, just as European sailors did in more recent historical times.
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The success of a biological invasion is context dependent, and yet two key concepts—the invasiveness of species and the invasibility of recipient ecosystems—are often defined and considered separately. We propose a framework that can elucidate the complex relationship between invasibility and invasiveness. It is based on trait-mediated interactions between species and depicts the response of an ecological network to the intrusion of an alien species, drawing on the concept of community saturation. Here, invasiveness of an introduced species with a particular trait is measured by its per capita population growth rate when the initial propagule pressure of the introduced species is very low. The invasibility of the recipient habitat or ecosystem is dependent on the structure of the resident ecological network and is defined as the total width of an opportunity niche in the trait space susceptible to invasion. Invasibility is thus a measure of network instability. We also correlate invasibility with the asymptotic stability of resident ecological network, measured by the leading eigenvalue of the interaction matrix that depicts trait-based interaction intensity multiplied by encounter rate (a pairwise product of propagule pressure of all members in a community). We further examine the relationship between invasibility and network architecture, including network connectance, nestedness and modularity. We exemplify this framework with a trait-based assembly model under perturbations in ways to emulate fluctuating resources and random trait composition in ecological networks. The maximum invasiveness of a potential invader (greatest intrinsic population growth rate) was found to be positively correlated with invasibility of the recipient ecological network. Additionally, ecosystems with high network modularity and high ecological stability tend to exhibit high invasibility. Where quantitative data are lacking we propose using a qualitative interaction matrix of the ecological network perceived by a potential invader so that the structural network stability and invasibility can be estimated from the literature or from expert opinion. This approach links network structure, invasiveness and invasibility in the context of trait-mediated interactions, such as the invasion of insects into mutualistic and antagonistic networks.
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We provide an overview of terrestrial animal translocations carried out for conservation purposes in Britain, summarising what has been achieved in recent decades and discussing the issues raised by this approach to conservation. In the last 40 years, at least nine species have been reintroduced following extinction in Britain (or at least one country within Britain), including five birds, one mammal, one amphibian and two invertebrates. Many more species have been translocated within Britain to establish additional populations in order to improve conservation status. We discuss the guidelines and protocols used to assess translocation projects in Britain, notably the IUCN guidelines, most recently revised in 2013. We also discuss the likely use of species translocations in future and suggest that, in our increasingly fragmented landscapes, they will have an important role to play in conservation restoration, especially for animals with limited mobility. Moving species around is a complex undertaking and our understanding of the inherent risks involved, including the risks from disease, has improved significantly in recent years. Conservation translocations should be considered in the context of species recovery targets and high standards should be maintained so that disease risks and other potentially negative impacts are minimised.
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Although much information has been accumulated on the effects of climate change on particular species worldwide, research aimed at assessing how such change influences biotic interactions from a community-wide perspective is still in its infancy. We contribute to filling in this gap by analyzing a 17-year (1996–2012) dataset that includes records of flower-visitation interactions between 12 butterfly species and 17 plant species in a coastal wetland area in northeastern Iberian Peninsula. We assessed the extent to which temporal asynchronies between plants and adult butterflies are influenced by different climatic variables that affect both plant and insect phenologies. Temperature and degree of aridity at various monthly summaries were used as predictors of the plant–butterfly phenological asynchrony. We identified the seasonal window with the greatest effect on asynchronies for two butterfly generations (spring and summer), and assessed whether the magnitude of asynchrony is associated with the level of butterfly specialization. We used generalized linear mixed models considering a total of 39 plant-butterfly interactions. Average asynchrony was higher in the spring generation and dry conditions during winter lead to decreased temporal overlap with flowers in this butterfly generation, whereas dry conditions in the spring lead to decreased temporal overlap in the summer butterfly generation. The magnitude of the effect was consistently small at the community level (all interactions pooled). Moreover, no clear climatic trend over the study time frame was detected. Finally, specialized and generalized butterflies in their resource use as adults were similarly vulnerable to asynchronies, in contrast to previous predictions of greater mutualistic disruptions in species with narrower niches. We conclude that a least in the Mediterranean region, phenological asynchronies might be more affected by aridity level than by temperature itself, and thus the former can be a key climatic trait to make better predictions in this region. This article is protected by copyright. All rights reserved.
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Nearly 10 y ago, we (1) critiqued the idea of Pleistocene rewilding (2), a misguided attempt to resurrect bygone ecosystems. Much has happened to the Earth’s biodiversity over the decade since the term “Pleistocene rewilding” was coined, most of it bad. More than half a billion people have been added to the world’s population, and ecosystems continue to be degraded at an alarming rate. A sixth mass extinction is underway, and poaching of megafauna has increased across sub-Saharan Africa. Unfortunately, one thing that has not happened is any serious attempt to scientifically study Pleistocene rewilding. Despite a number of publicized Pleistocene rewilding projects (Oostvaardersplassen in The Netherlands and Pleistocene Park in Siberia), we have yet to see any quantitative data concerning the impacts of megafauna reintroductions.
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Trophic rewilding is an ecological restoration strategy that uses species introductions to restore top-down trophic interactions and associated trophic cascades to promote self-regulating biodiverse ecosystems. Given the importance of large animals in trophic cascades and their widespread losses and resulting trophic downgrading, it often focuses on restoring functional megafaunas. Trophic rewilding is increasingly being implemented for conservation, but remains controversial. Here, we provide a synthesis of its current scientific basis, highlighting trophic cascades as the key conceptual framework, discussing the main lessons learned from ongoing rewilding projects, systematically reviewing the current literature, and highlighting unintentional rewilding and spontaneous wildlife comebacks as underused sources of information. Together, these lines of evidence show that trophic cascades may be restored via species reintroductions and ecological replacements. It is clear, however, that megafauna effects may be affected by poorly understood trophic complexity effects and interactions with landscape settings, human activities, and other factors. Unfortunately, empirical research on trophic rewilding is still rare, fragmented, and geographically biased, with the literature dominated by essays and opinion pieces. We highlight the need for applied programs to include hypothesis testing and science-based monitoring, and outline priorities for future research, notably assessing the role of trophic complexity, interplay with landscape settings, land use, and climate change, as well as developing the global scope for rewilding and tools to optimize benefits and reduce human–wildlife conflicts. Finally, we recommend developing a decision framework for species selection, building on functional and phylogenetic information and with attention to the potential contribution from synthetic biology.
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The extent that biotic interactions and dispersal influence species ranges and diversity patterns across scales remains an open question. Answering this question requires framing an analysis on the frontier between species distribution modelling (SDM), which ignores biotic interactions and dispersal limitation, and community ecology, which provides specific predictions on community and meta-community structure and resulting diversity patterns such as species richness and functional diversity. Using both empirical and simulated datasets, we tested whether predicted occurrences from fine-resolution SDMs provide good estimates of community structure and diversity patterns at resolutions ranging from a resolution typical of studies within reserves (250 m) to that typical of a regional biodiversity study (5 km). For both datasets, we show that the imprint of biotic interactions and dispersal limitation quickly vanishes when spatial resolution is reduced, which demonstrates the value of SDMs for tracking the imprint of community assembly processes across scales.
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Ex-situ conservation strategies for threatened species often require long-term commitment and financial investment to achieve management objectives. Here, we interpret the decision to adopt ex-situ management for a target species as the end point of several linked decisions. Logically, one must first decide which specific management actions are most likely to achieve the fundamental objectives of the recovery plan, with or without the use of ex-situ populations. Once this first decision has been made, one can decide whether to establish an ex-situ population, accounting for the probability of success in the initial phase, for example the probability of successful breeding in captivity. Approaching these decisions in the reverse order (attempting to establish an ex-situ population before its purpose is clearly defined) can lead to a poor allocation of resources. We use the recovery program for the threatened spotted tree frog (Litoria spenceri) in south-eastern Australia as an example to illustrate our decision framework. Across a range of possible management actions, only those including ex-situ management were expected to provide > 50% probability of species' persistence, but they came at a greater financial cost than in-situ-only alternatives. The expected benefits of ex-situ actions would also be offset by additional uncertainty and stochasticity associated with establishing and maintaining ex-situ populations. Naïvely implementing ex-situ conservation strategies can lead to inefficient management. We provide a framework to help managers explicitly evaluate objectives, management options and the probability of success prior to establishing a captive colony of any given species. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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Humans, unlike any other multicellular species in Earth’s history, have emerged as a global force that is transforming the ecology of an entire planet. It is no longer possible to understand, predict, or successfully manage ecological pattern, process or change without understanding why and how humans reshape these over the long-term. Here, a general causal theory is presented to explain why human societies gained the capacity to globally alter the patterns, processes and dynamics of ecology and how these anthropogenic alterations unfold over time and space as societies themselves change over human generational time. Building on existing theories of ecosystem engineering, niche construction, inclusive inheritance, cultural evolution, ultrasociality, and social change, this theory of anthroecological change holds that sociocultural evolution of subsistence regimes based on ecosystem engineering, social specialization and nonkin exchange, or “sociocultural niche construction”, is the main cause of both the long-term upscaling of human societies and their unprecedented transformation of the biosphere. Human sociocultural niche construction can explain, where classic ecological theory cannot, the sustained transformative effects of human societies on biogeography, ecological succession, ecosystem processes, and the ecological patterns and processes of landscapes, biomes and the biosphere. Anthroecology theory generates empirically testable hypotheses on the forms and trajectories of long-term anthropogenic ecological change that have significant theoretical and practical implications across the subdisciplines of ecology and conservation. Though still at an early stage of development, anthroecology theory aligns with and integrates established theoretical frameworks including social-ecological systems, social metabolism, countryside biogeography, novel ecosystems and anthromes. The "fluxes of nature" are fast becoming "cultures of nature". To investigate, understand, and address the ultimate causes of anthropogenic ecological change, not just the consequences, human sociocultural processes must become as much a part of ecological theory and practice as biological and geophysical processes are now. Strategies for achieving this goal and for advancing ecological science and conservation in an increasingly anthropogenic biosphere are presented.
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Novel assemblages of native and introduced species characterize a growing proportion of ecosystems worldwide. Some introduced species have contributed to extinctions, even extinction waves, spurring widespread efforts to eradicate or control them. We propose that trophic cascade theory offers insights into why introduced species sometimes become harmful, but in other cases stably coexist with natives and offer net benefits. Large predators commonly limit populations of potentially irruptive prey and mesopredators, both native and introduced. This top-down force influences a wide range of ecosystem processes that often enhance biodiversity. We argue that many species, regardless of their origin or priors, are allies for the retention and restoration of biodiversity in top-down regulated ecosystems. Copyright © 2015 Elsevier Ltd. All rights reserved.
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