Contemporary Environmental Change Research Articles

Genetic diversity in the traditional cultivars and wild ancestor of near-threatened Japanese iris (Iris ensata Thunb.)

Wild relatives of cultivars are crucial sources of genetic variation for further enhancement, yet they face potential threats due to contemporary environmental changes. Iris ensata var. spontanea, a wild progenitor of the Japanese iris cultivars (I. ensata var. ensata), is extensively cultivated in Japanese gardens, is distributed across mesic meadows and wetlands in Japan and East Asia. This species is currently threatened owing to habitat loss linked to land use alterations. We assessed genetic diversity and phylogenetic relationships in 32 wild accessions and the 14 principal Edo Group of Japanese iris cultivars, originally bred during the Edo period (1600–1868). In the phylogenetic tree, the cultivars formed a cluster with reduced inbreeding coefficients, suggesting a singular origin and interbreeding between the genetically distinct accessions. Conversely, wild accessions exhibited greater overall genetic diversity and higher inbreeding coefficients than cultivars, indicating frequent inbreeding within divergent natural populations. Our findings highlight the distinct genetic reservoirs of both wild accessions and Edo cultivars, although the former may face inbreeding challenges. Urgent conservation action is needed to ensure the genetic diversity of wild populations as natural resources.

Improving the Growth and Productivity of Two Varieties of Mung Bean (Vigna radiata L.) by using Different Cultivation Methods and Dates

Background: Mung bean is characterized by its ability to withstand water scarcity due to its short life span, so it can be introduced into agricultural rotation systems and despite especially when there is a lack of humidity and contemporary environmental changes. Despite the importance of this crop, its productivity rate in Iraq is still low compared to global production. The dates and methods of cultivation of the mungbean crop must be determined accurately to suit the specifications of local varieties adapted to the changing environmental conditions. Methods: The field study was applied in two fields: the first in Nineveh Governorate and the second in Erbil Governorate / Republic of Iraq. Three factors included, first: two varieties of local mung bean (black and green), second: different cultivation methods (furrow and lines) and the third: planting dates (May 15, June 15 and July 15). The study was designed as a factor experiment a design (R.C.B.D) with three replicates. Result: The first variety superior significantly in the two sites with the qualities of (plant height, leaf area, leaf area index, seed yield, Biological yield and harvest index. From the results of the dates, we note a significant superiority of the first date number of seeds.pod-1 while the third date significantly outperformed the germination percentage for the two sites. First planting method significant superiority in most of the studied characterists and for the two research sites. Significant superiority was recorded for the interactions of research factors and their levels.

Opportunities for China’s Agricultural Heritage Systems under the “Digital Nomadism” Trend—A Stakeholder-Weighted Approach

Agricultural heritage systems are appreciated worldwide for their significant environmental and cultural values. However, the sustainability of these systems has been compromised by environmental issues due to intensive human activities and socio-economic changes. Research has noticed that “digital nomadism” is providing a new opportunity for the sustainable development and transformation of these systems, regarded as “digital nomad-friendly” destinations. Nevertheless, comprehensive research on this new trend has been limited except for a few individual case studies. This study is the first to investigate the sustainable development of agricultural heritages considering the growing phenomenon of digital nomadism on a large scale. Based on in-depth stakeholder interviews, we introduced the Digital Nomad-Friendly (DNF) score—a comprehensive indicator system chosen and weighted by stakeholders. The DNF scores of 189 China National Important Agricultural Heritage System (China-NIAHS) sites were evaluated, and their distributions were analyzed on a national scale in China. The results highlight the importance of natural landscape and cultural value in the eyes of digital nomads, particularly emphasizing aesthetic landscape features, climatic suitability, and a community atmosphere. Sites with the highest DNF scores are located mostly in the Zhejiang and Yunnan provinces, sharing characteristics that appeal to digital nomads. The DNF scores exhibit regional variations, with high-DNF-score sites being concentrated in southwestern and southeastern China. By enhancing our understanding of digital nomads’ preferences and the influencing factors, this study provides valuable insights for the environmental management, policymaking, and sustainable development of China-NIAHS sites considering contemporary environmental and social changes.

Phenotypic plasticity and genetic diversity shed light on endemism of rare Boechera perstellata and its potential vulnerability to climate warming.

The rapid pace of contemporary environmental change puts many species at risk, especially rare species constrained by limited capacity to adapt or migrate due to low genetic diversity and/or fitness. But the ability to acclimate can provide another way to persist through change. We compared the capacity of rare Boechera perstellata (Braun's rockcress) and widespread B. laevigata to acclimate to change. We investigated the phenotypic plasticity of growth, biomass allocation, and leaf morphology of individuals of B. perstellata and B. laevigata propagated from seed collected from several populations throughout their ranges in a growth chamber experiment to assess their capacity to acclimate. Concurrently, we assessed the genetic diversity of sampled populations using 17 microsatellite loci to assess evolutionary potential. Plasticity was limited in both rare B. perstellata and widespread B. laevigata, but differences in the plasticity of root traits between species suggest that B. perstellata may have less capacity to acclimate to change. In contrast to its widespread congener, B. perstellata exhibited no plasticity in response to temperature and weaker plastic responses to water availability. As expected, B. perstellata also had lower levels of observed heterozygosity than B. laevigata at the species level, but population-level trends in diversity measures were inconsistent due to high heterogeneity among B. laevigata populations. Overall, the ability of phenotypic plasticity to broadly explain the rarity of B. perstellata versus commonness of B. laevigata is limited. However, some contextual aspects of our plasticity findings compared with its relatively low genetic variability may shed light on the narrow range and habitat associations of B. perstellata and suggest its vulnerability to climate warming due to acclimatory and evolutionary constraints.

Prodigious shift in provenance across Permian-Triassic Boundary at Guryul Ravine Section, Kashmir, Tethys Himalaya, India: Evidences from Sr and Nd isotopes

The Permian-Triassic Boundary (PTB) section (Late Permian Zewan Formation and Early Triassic Khunamuh Formation) at Guryul Ravine (Kashmir, India) preserves potentially important information about the depositional conditions and provenance changes across the PTB. Several palaeobiological, sedimentological and geochemical studies have been conducted on this archetypal section to understand the causes of mass extinction at the PTB, however no integrated chemo-stratigraphic study focusing on provenance and geodynamics has been attempted. In the present study, samples from a 36 m thick interval across the PTB are analysed for major and trace element concentrations, Sr-, Nd- and Corg isotope geochemistry along with TOC (total organic carbon) contents to understand the contemporary environmental and provenance changes. The Late Permian Zewan Formation have relatively low chemical index of alteration (CIA) values (55–77) and low αAlCa (0.1–12.6), αAlNa (0.7–9.6), αAlMg (1.0–6.1) values, implying moderate weathering conditions; whereas the Early Triassic sediments of overlying Khunamuh Formation show higher CIA (69–79) and αAlCa (1.4–14.0), αAlNa (2.2–11.5), αAlMg (2.0–6.4) values indicating more intense chemical weathering conditions. The vertical profiles of δ13Corg, δ34Spyr and various redox-indicators suggest euxinic-anoxic condition during the latest Permian, and show a significant change in depositional conditions from anoxic to oxic across the PTB. The significant finding of the present study is the dramatic change of Sr- and Nd isotopic compositions across the PTB, indicating remarkable shift in provenance. The Late Permian samples show much less-radiogenic ɛNd(0) (avg. –15.27), radiogenic 87Sr/S6Sr(0) (avg. 0.72409) and older TDM ages (1.35–1.56 Ga) compared to the early Triassic samples (avg. εNd(0) = −9.49,87Sr/S6Sr(0) = 0.719282, TDM = 1.71–1.76 Ga). The εNd(0) and 87Sr/S6Sr(0) composition of Late Permian rocks overlap with the signatures of Tethyan Himalaya and Neoproterozoic-Cambrian Marwar Supergroup of NW India, indicating similar old cratonic sources. Higher εNd(0), younger TDM ages and lower 87Sr/86Sr(0) in Triassic samples suggest contribution from juvenile sources and Panjal volcanics, Cadimian arc of Cimmeria or African-Nubian shield could be the likely source terrains.

A highly effective incubation strategy enhanced the urban bird hatch success

Urbanization is currently considered one of the most rapid types of global environmental change. Urban habitats are biotically and abiotically different from their rural areas, i.e., the ambient temperature, predator, and food availability. These novel challenges create new selection pressures, which allow one to investigate eco-evolutionary responses to contemporary environmental change. A total of 118 breeding nests were monitored for nest predation in both urban and rural areas from 2018 to 2020. We used environmental factors from urban and rural areas and behavioral data from 439 Chinese Blackbird (Turdus mandarinus) valid incubation days to understand the impact of urbanization on the incubation behavior of blackbirds and its adaptation mechanism to the urban environment. Cities have warmer ambient temperatures and lower predation pressures than rural areas. Urban blackbirds chose the incubation strategy with shorter and more bouts, while rural blackbirds selected the incubation strategy with longer and fewer bouts. The plasticity of incubation behavior of urban blackbirds was higher than that of rural areas, and the range of egg temperature was also higher than that of rural areas. In addition, incubation temperature and the number of bouts per day were the key factors affecting the day survival rate of blackbirds, and the hatching rate of urban blackbirds was higher than that of rural blackbirds. Our results provide evidence for behavioral shifts in blackbirds during adaptation to urbanization and support the central role of behavioral adaptation in the successful colonization of new environments by wildlife. These help us understand the behavioral characteristics required for wildlife to live in cities and the urban adaptors faced environmental pressures.

Relict permafrost preserves megafauna, insects, pollen, soils and pore-ice isotopes of the mammoth steppe and its collapse in central Yukon

In eastern Beringia (unglaciated Alaska and western Yukon), the Pleistocene-Holocene transition was characterised by rapid changes in plant, insect and mammal communities as the mammoth steppe ecosystem was replaced, first by shrub tundra and later boreal forest. These changes indicate a transition from well drained terrain with deep active layers to wetter, cooler soils, to which steppe-tundra vegetation was poorly adapted. The nature and precise timing of these events is not well resolved, particularly in central Yukon where regional climate may have been strongly affected by the retreating Cordilleran-Laurentide ice sheet complex. Resolving this uncertainty is not only important for understanding past ecosystems, but also provides a long-term perspective for contemporary environmental change and shrub expansion that affects large areas of northern high-latitudes today. Here, we report chronology (41 radiocarbon dates), stratigraphy, pore-ice δ2H/δ18O measurements, pollen data, megafauna remains and fossil insect assemblages from a permafrost-preserved loessal sequence in central Yukon, named Lucky Lady. The site spans the interval from ca. 17,000 to 8000 cal yr BP (calibrated years before C.E. 1950) and records the Pleistocene-Holocene transition in exceptional resolution. Full glacial environments (ca. 16,500 cal yr BP) supported elements of steppe-tundra vegetation and an insect fauna dominated by Connatichela artemisiae - an endemic weevil indicating warm soil temperatures. The collapse of the mammoth steppe ecosystem began with slowing of loess accumulation and development of paleosol ca. 13,480 cal yr BP. At this time, C. artemisiae remains become infrequent and Artemisia pollen decline to be replaced by Cyperaceae (ca. 13,220), before mesic, shrub taxa (likely dwarf Betula and Salix) becomes dominant ca. 13,210 cal yr BP. The establishment of shrub tundra is associated with rapid changes in δ2H/δ18O measurements, suggesting that ecological turnover coincided with a shift in atmospheric conditions and moisture availability. Finally, boreal vegetation communities became established ca. 10,680 cal yr BP. The replacement of steppe-tundra vegetation in central Yukon lagged other areas of eastern Beringia by as much as 1000 years and coincided with rapid deglaciation during the Bølling–Allerød time-period (14,600–12,900 cal yr BP). Turnover in insect and vegetation communities took place in ca. 40 years as shrub tundra became dominant. This rapid turnover has parallels with contemporary Arctic greening and re-emphasises the sensitivity of high-latitude environments to climate change.

Demographic inference provides insights into the extirpation and ecological dominance of eusocial snapping shrimps.

Although eusocial animals often achieve ecological dominance in the ecosystems where they occur, many populations are unstable, resulting in local extinction. Both patterns may be linked to the characteristic demography of eusocial species-high reproductive skew and reproductive division of labor support stable effective population sizes that make eusocial groups more competitive in some species, but also lower effective population sizes that increase susceptibility to population collapse in others. Here, we examine the relationship between demography and social organization in Synalpheus snapping shrimps, a group in which eusociality has evolved recently and repeatedly. We show using coalescent demographic modeling that eusocial species have had lower but more stable effective population sizes across 100,000 generations. Our results are consistent with the idea that stable population sizes may enable competitive dominance in eusocial shrimps, but they also suggest that recent population declines are likely caused by eusocial shrimps' heightened sensitivity to environmental changes, perhaps as a result of their low effective population sizes and localized dispersal. Thus, although the unique life histories and demography of eusocial shrimps have likely contributed to their persistence and ecological dominance over evolutionary time scales, these social traits may also make them vulnerable to contemporary environmental change.

Can we learn from the past? Towards better analogies and historical inference in society-environmental change research

In light of the challenges posed by contemporary environmental changes, interest in past environmental impacts and societies’ responses to them is burgeoning. The main strength of such research lies in its ability to analyze completed society-environment interactions. Scholars have argued that such analyses can improve our understanding of present challenges and offer useful lessons to guide adaptation responses. Yet despite considerable differences between past and present societies, our inherently limited knowledge of the past and our changing understanding of it, much of this research uses historical antecedents uncritically, assuming that past societal impacts and responses are directly analogous to contemporary ones. We argue that this approach is unsound both methodologically and theoretically, thus drawing insights that might offer an erroneous course of action.To illustrate the challenges in drawing historical analogies, we outline several fundamental differences between past and present societies as well as broader limitations of historical research. Based on these points, we argue that scholars who apply historical inference in their work should do so critically, while reflecting on the objectives of learning from the past and the limitations of this process. We suggest a number of ways to improve past-present analogies, such as defining more explicitly what we can learn from the past, clarifying the rationale for using the analogy, and reducing the number of variables compared between past and present.

Unveil the unseen: Using LiDAR to capture time‐lag dynamics in the herbaceous layer of European temperate forests

Abstract To understand time‐lag dynamics in the response of biodiversity to contemporary environmental changes (e.g. macroclimate warming and atmospheric pollution), we need to consider former anthropogenic forcing factors such as past land uses and management practices that can have both compounding and confounding effects. This is especially true in European temperate forests, where legacies from past human activities have left strong imprints on today’s understorey plant species composition, generating long‐term lagging effects which can be mistakenly attributed to more recent macro‐environmental changes. By combining the expertise of plant, soil and historical ecologists together with remote sensing scientists, we review the potential of light detection and ranging (LiDAR) to unveil ghosts from the past in terms of former land uses and management practices. We show that imprints from past land uses and management practices can still be captured today through well‐chosen LiDAR‐derived variables describing, at sub‐decimetre scale, the vertical and horizontal micro‐variations of vegetation and terrain structure hidden below treetops. Synthesis. We encourage plant and soil ecologists to use LiDAR data and to work with historians, archaeologists and remote sensing scientists in order to select meaningful LiDAR‐derived variables to account for time‐lagged biotic responses to long‐term macro‐environmental changes.

Rapid genetic divergence and mitonuclear discordance in the Taliang knobby newt ( Liangshantriton taliangensis, Salamandridae, Caudata) and their driving forces.

The Hengduan Mountains Region (HMR) is the largest “evolutionary frontier” of the northern temperate zone, and the origin and maintenance of species in this area is a research hotspot. Exploring species-specific responses to historical and contemporary environmental changes will improve our understanding of the role of this region in maintaining biodiversity. In this study, mitochondrial and microsatellite diversities were used to assess the contributions of paleogeological events, Pleistocene climatic oscillations, and contemporary landscape characteristics to the rapid intraspecific diversification of Liangshantriton taliangensis, a vulnerable amphibian species endemic to several sky-island mountains in the southeastern HMR. Divergence date estimations suggested that the East Asian monsoon, local uplifting events (Xigeda Formation strata), and Early-Middle Pleistocene transition (EMPT) promoted rapid divergence of L. taliangensis during the Pleistocene, yielding eight mitochondrial lineages and six nuclear genetic lineages. Moreover, population genetic structures were mainly fixed through isolation by resistance. Multiple in situ refugia were identified by ecological niche models and high genetic diversity, which played crucial roles in the persistence and divergence of L. taliangensis during glacial-interglacial cycles. Dramatic climatic fluctuations further promoted recurrent isolation and admixing of populations in scattered glacial refugia. The apparent mitonuclear discordance was likely the result of introgression by secondary contact and/or female-biased dispersal. Postglacial expansion generated two major secondary contact zones (Ganluo (GL) and Chuhongjue (CHJ)). Identification of conservation management units and dispersal corridors offers important recommendations for the conservation of this species.

Population genomics of free-ranging Great Plains white-tailed and mule deer reflects a long history of interspecific hybridization.

Hybridization is a natural process at species‐range boundaries that may variably promote the speciation process or break down species barriers but minimally will influence management outcomes of distinct populations. White‐tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) have broad and overlapping distributions in North America and a recognized capacity for interspecific hybridization. In response to contemporary environmental change to any of one or multiple still‐unknown factors, mule deer range is contracting westward accompanied by a westward expansion of white‐tailed deer, leading to increasing interactions, opportunities for gene flow, and associated conservation implications. To quantify genetic diversity, phylogenomic structure, and dynamics of hybridization in sympatric populations of white‐tailed and mule deer, we used mitochondrial cytochrome b data coupled with SNP loci discovered with double‐digest restriction site‐associated DNA sequencing. We recovered 25,018 SNPs across 92 deer samples from both species, collected from two regions of western Kansas. Eight individuals with unambiguous external morphology representing both species were of hybrid origin (8.7%), and represented the product of multi‐generational backcrossing. Mitochondrial data showed both ancient and recent directional discordance with morphological species assignments, reflecting a legacy of mule deer males mating with white‐tailed deer females. Mule deer had lower genetic diversity than white‐tailed deer, and both mitochondrial and nuclear data suggest contemporary mule deer effective population decline. Landscape genetic analyses show relative isolation between the two study regions for white‐tailed deer, but greater connectivity among mule deer, with predominant movement from north to south. Collectively, our results suggest a long history of gene flow between these species in the Great Plains and hint at evolutionary processes that purge incompatible functional genomic elements as a result of hybridization. Surviving hybrids evidently may be reproductive, but with unknown consequences for the future integrity of these species, population trajectories, or relative susceptibility to emerging pathogens.

Urbanisation weakens selection on the timing of breeding and clutch size in blue tits but not in great tits

Urbanisation is a globally occurring phenomenon and is predicted to continue increasing rapidly. Urban ecosystems present novel environments and challenges which species must acclimate or adapt to. These novel challenges alter existing or create new selection pressures on behaviours which provide an opportunity to investigate eco-evolutionary responses to contemporary environmental change. We used 7 years of breeding data from urban and forest populations of blue and great tits to understand whether selection for timing of breeding or clutch size differed between the two habitats and species. We found that urban great tits laid eggs earlier than their forest counterparts, but there was no evidence of a difference in selection for earlier breeding. Blue tits, however, did not differ in timing of egg laying between the two habitats, but selection for earlier laying was weaker in the urban environment. Both species laid smaller clutches in the urban site and had positive selection for larger clutch sizes which did not differ in strength for the great tits but did for blue tits, with weaker selection in the urban population. Our results suggest that food availability for nestlings may be constraining urban birds, and that the temporal cues females use to time breeding correctly, such as tree budburst and food availability, may be absent or reduced in urban areas due to lower caterpillar availability. These results have implications for our understanding of the adaptation of wild animals to city life.Significance statementUrbanisation is expanding rapidly and changing the environment many species live in. A key challenge is to understand how species adapt to the urban environment, why some species can adapt, why others cannot and what we can do to ensure that cities are ecologically sustainable and biodiversity rich. Here we show that the strength of natural selection for early breeding and larger clutch size is weaker in urban than non-urban blue tits, likely due to reduced and irregular availability of natural insect food in urban areas. This effect was not found in great tits. Thus, urbanisation can alter the selection pressures wild animals are exposed to, but this effect may differ between species, even when closely related. This has implications for our understanding of how species adapt to urban life.

Life history, climate and biogeography interactively affect worldwide genetic diversity of plant and animal populations

Understanding how biological and environmental factors interactively shape the global distribution of plant and animal genetic diversity is fundamental to biodiversity conservation. Genetic diversity measured in local populations (GDP) is correspondingly assumed representative for population fitness and eco-evolutionary dynamics. For 8356 populations across the globe, we report that plants systematically display much lower GDP than animals, and that life history traits shape GDP patterns both directly (animal longevity and size), and indirectly by mediating core-periphery patterns (animal fecundity and plant dispersal). Particularly in some plant groups, peripheral populations can sustain similar GDP as core populations, emphasizing their potential conservation value. We further find surprisingly weak support for general latitudinal GDP trends. Finally, contemporary rather than past climate contributes to the spatial distribution of GDP, suggesting that contemporary environmental changes affect global patterns of GDP. Our findings generate new perspectives for the conservation of genetic resources at worldwide and taxonomic-wide scales.

Modelling suspended sediment discharge in a glaciated Arctic catchment–Lake Peters, Northeast Brooks Range, Alaska

AbstractSeasonal suspended sediment transfer in glaciated catchments is responsive to meteorological, geomorphological, and glacio‐fluvial conditions, and thus is a useful indicator of environmental system dynamics. Knowledge of multifaceted fluvial sediment‐transfer processes is limited in the Alaskan Arctic – a region sensitive to contemporary environmental change. For two glaciated sub‐catchments at Lake Peters, northeast Brooks Range, Alaska, we conducted a two‐year endeavour to monitor the hydrology and meteorology, and used the data to derive multiple‐regression models of suspended sediment load. Statistical selection of the best models shows that incorporating meteorological or temporal explanatory variables improves performances of turbidity‐ and discharge‐based sediment models. The resulting modelled specific suspended sediment yields to Lake Peters are: 33 (20–60) t km−2 yr−1 in 2015, and 79 (50–140) t km−2 yr−1 in 2016 (95% confidence band estimates). In contrast to previous studies in Arctic Alaska, fluvial suspended sediment transfer to Lake Peters was primarily influenced by rainfall, and secondarily influenced by temperature‐driven melt processes associated with clockwise diurnal hysteresis. Despite different sub‐catchment glacier coverage, specific yields were the same order of magnitude from the two primary inflows to Lake Peters, which are Carnivore Creek (128 km2; 10% glacier coverage) and Chamberlin Creek (8 km2; 23% glacier coverage). Seasonal to longer‐term sediment exhaustion and/or contrasting glacier dynamics may explain the lower than expected relative specific sediment yield from the more heavily glacierized Chamberlin Creek catchment. Absolute suspended sediment yield (t yr−1) from Carnivore Creek to Lake Peters was 27 times greater than from Chamberlin Creek, which we attribute to catchment size and sediment supply differences. Our results provide a foundational understanding of the current sediment transfer regime and are useful for predicting changes in fluvial sediment transport in glaciated Alaskan Arctic catchments.

Remarkable insensitivity of acorn ant morphology to temperature decouples the evolution of physiological tolerance from body size under urban heat islands.

Environmental temperature can alter body size and thermal tolerance, yet the effects of temperature rise on the size-tolerance relationship remain unclear. Terrestrial ectotherms with larger body sizes typically exhibit greater tolerance of high (and low) temperatures. However, while warming tends to increase tolerance of high temperatures through phenotypic plasticity and evolutionary change, warming tends to decrease body size through these mechanisms and thus might indirectly contribute to worse tolerance of high temperatures. These contrasting effects of warming on body size, thermal tolerance, and their relationship are increasingly important in light of global climate change. Here, we used replicated urban heat islands to explore the size-tolerance relationship in response to warming. We performed a common garden experiment with a small acorn-dwelling ant species collected from urban and rural populations across three different cities and reared under five laboratory rearing temperatures from 21 to 29 °C. We found that acorn ant body size was remarkably insensitive to laboratory rearing temperature (ant workers exhibited no phenotypic plasticity in body size across rearing temperature) and among populations experiencing cooler rural versus warmer urban environmental temperatures (no evolved differences in body size between urban and rural populations). Further, this insensitivity of body size to temperature was highly consistent across each of the three cities we examined. Because body size was robust to temperature variation, previously described plastic and evolved shifts in heat (and cold) tolerance in acorn ant responses to urbanization were shown to be independent of shifts in body size. Indeed, genetic (colony-level) correlations between heat and cold tolerance traits and body size revealed no significant association between size and tolerance. Our results show how typical trait correlations, such as between size and thermal tolerance, might be decoupled as populations respond to contemporary environmental change.

Rethinking restoration targets for American chestnut using species distribution modeling

Given the scale and speed of contemporary environmental changes, intensive conservation interventions are increasingly being proposed that would assist the evolution of adaptive traits in threatened species. The ambition of these projects is tempered by a number of concerns, including the potential maladaptation of manipulated organisms for contemporary and future climatic conditions in their historical ranges. Following the guidelines of the International Union for the Conservation of Nature, we use a species distribution model (SDM) to consider the potential impact of climate change on the distribution and quantity of suitable habitat for American chestnut (Castanea dentata), a functionally extinct forest species that has been the focus of various restoration efforts for over 100 years. Consistent with other SDMs for North American trees, our model shows contraction of climatically suitable habitat for American chestnut within the species’ historical range and the expansion of climatically suitable habitat in regions to the north of it by 2080. These broad changes have significant implications for restoration practice. In particular, they highlight the importance of germplasm conservation, local adaptation, and addressing knowledge gaps about the interspecific interactions of American chestnut. More generally, this model demonstrates that the goals of assisted evolution projects, which often aim to maintain species in their native ranges, need to account for the uncertainty and novelty of future environmental conditions.

Invasive uncertainties: environmental change and the politics of limited science

ABSTRACTPolitical actors often want to know as much as possible about the social effects of new and unforeseen environmental changes. The natural scientists who study environmental change, however, cannot always provide the precise environmental knowledge desired by political actors. This is because to study contemporary environmental change is to study systems that are immensely interactive and complex, a fact that often limits scientists’ ability to provide full guarantees regarding future impacts. My question, then, is how do the limitations of performing science about environmental change interact with the politics of environmental change? To answer this question, I examine how a particular set of ecologists, biologists, and others struggled to provide guarantees regarding the future migration of Asian carp, an invasive species that was threatening to enter the Great Lakes and potentially disrupt existing socio-environmental relationships. Data are derived from a combination of 32 semi-structured interviews and document analysis. I discuss these data using a social-biophysical stratification framework, and find that the limitations of performing science about environmental change can restructure political opportunities for enacting or invalidating environmental interventions, and also that these limitations in themselves closely tied the performance of science to local environmental politics.

Demographic history and spatial genetic structure in a remnant population of the subtropical tree Anadenanthera colubrina var. cebil (Griseb.) Altschul (Fabaceae)

A remnant population of Anadenanthera colubrina var. cebil in Northern Argentina showed a mixed mating system, high genetic diversity, and moderate spatial genetic structure, which was stronger in saplings than in adults. Demographic history analyses revealed an ancient population expansion. Despite high genetic diversity, high inbreeding suggests caution in the use of this stand as seed source. Information on fine-scale spatial genetic structure (FSGS) and demographic history is essential to determine which mechanisms are responsible for population persistence and evolution. This is particularly important in fragmented biomes, such as the seasonally dry tropical forests. To assess the level of genetic diversity and population genetic structure in a remnant population of A. colubrina var. cebil, and to evaluate the influence of historical and contemporary environmental change on the genetic constitution of this population. Eight microsatellites were typed in 60 adults and 59 saplings. The existence of (non-spatial) genetic clusters was evaluated using STRUCTURE and PCAs. FSGS was evaluated by kinship analyses and sPCA. MCMCglmm models were used to provide insights into factors underlying FSGS. Demographic history was studied using bottleneck statistics and approximate Bayesian computation. We found high levels of genetic diversity and high inbreeding. Genetic structure was stronger in saplings than in adult trees, probably due to assortative mating, and was not explained by altitude or DBH. Demographic analyses suggested an ancient population expansion. Patterns of inbreeding and relatedness suggest a mixed mating system. High genetic diversity and moderate genetic structure suggest long-term population viability. High inbreeding suggests caution when using this stand as a source of material for reforestation.

Dryland belt of Northern Eurasia: contemporary environmental changes and their consequences

The dryland belt (DLB) in Northern Eurasia is the largest contiguous dryland on Earth. During the last century, changes here have included land use change (e.g. expansion of croplands and cities), resource extraction (e.g. coal, ores, oil, and gas), rapid institutional shifts (e.g. collapse of the Soviet Union), climatic changes, and natural disturbances (e.g. wildfires, floods, and dust storms). These factors intertwine, overlap, and sometimes mitigate, but can sometimes feedback upon each other to exacerbate their synergistic and cumulative effects. Thus, it is important to properly document each of these external and internal factors and to characterize the structural relationships among them in order to develop better approaches to alleviating negative consequences of these regional environmental changes. This paper addresses the climatic changes observed over the DLB in recent decades and outlines possible links of these changes (both impacts and feedback) with other external and internal factors of contemporary regional environmental changes and human activities within the DLB.