The goal of this paper is the construction of measures μ on ℝⁿ enjoying three conflicting but fortunately compatible properties: (i) μ is a sum of weighted Dirac masses on a locally finite set, (ii) ...the Fourier transform μ̂ of μ is also a sum of weighted Dirac masses on a locally finite set, and (iii) μ is not a generalized Dirac comb. We give surprisingly simple examples of such measures. These unexpected patterns strongly differ from quasicrystals, they provide us with unusual Poisson’s formulas, and they might give us an unconventional insight into aperiodic order.
Invasive alien species (IASs) on islands have broad impacts across biodiversity, agriculture, economy, health and culture, which tend to be stronger than on continents. Across small-island developing ...states (SIDSs), although only a small number of IASs are widely distributed, many more, including those with greatest impact, are found on only a small number of islands. Patterns of island invasion are not consistent across SIDS geographic regions, with differences attributable to correlated patterns in island biogeography and human development. We identify 15 of the most globally prevalent IASs on islands. IAS impacts on islands are exacerbated through interactions with a number of other global change threats, including over-exploitation, agricultural intensification, urban development and climate change. Biosecurity is critical in preventing IAS invasion of islands. Eradication of IASs on islands is possible at early stages of invasion, but otherwise is largely restricted to invasive mammals, or otherwise control is the only option. Future directions in IAS management and research on islands must consider IASs within a broader portfolio of threats to species, ecosystems and people's livelihoods on islands. We advocate for stronger collaborations among island countries and territories faced with the same IASs in similar socio-ecological environments.
Aim: Island tropical montane cloud forests (TMCFs) host a disproportionally high share of the global biodiversity and provide critical ecosystem services to vulnerable insular societies. However, ...this ecosystem is imperilled by anthropogenic impacts including climate change that might push TMCFs towards higher elevations. The elevation at which TMCFs start varies greatly among islands and may depend on topographically driven local climate, which may in turn be influenced by large-scale climate. Thus, a necessary prerequisite to assessing the vulnerability of island TMCFs to climate change is to determine the role of island features versus regional climate in influencing local climate at the lower TMCF ecotone. Location: Tropical islands. Methods: An extensive literature review of the elevation at which island TMCFs start was undertaken. This elevation was modelled as a function of the altitude of the lifting condensation level (LCL) imposed by regional climate, island maximum elevation and upwind forest loss over the past 15 years. Results: The elevation of the lower TMCF boundary was found to have been reported for 93 islands worldwide. TMCFs starts from as low as 300 m on the small islands of Kosrae (Micronesia; maximum elevation = 628 m) and Aneityum (Vanuatu; 852 m) to a maximum of 1,600 m on the large islands of Cuba (1,974 m) and Hispaniola (3,175 m), providing a spectacular example of the 'Massenerhebung effect'. Both regional climate (LCL altitude) and island features (maximum elevation) influenced the elevation of the lower TMCF boundary, and these variables together accounted for 79% of the variance. Main conclusions: On islands, climate change is likely to cause significant but small upslope shifts of the LCL and subsequently of TMCF lower boundary elevation in the future (+4.4 m for each 1°C increase in temperature). TMCF clearing and biological invasions might appear to be more pressing threats.
Buildings are the largest consumer of energy and greatest contributor to climate change in the United States—consuming approximately half of energy produced and contributing close to half of ...greenhouse gas emissions. Building designers, contractors, and owners currently have few methods to effectively control a building's life cycle energy and environmental impacts during the design phase. Managing and reducing these impacts during design requires rapid information turnaround and decision-making. When left unconsidered, poor environmental design decisions leave potential design value uncaptured. This research combines life cycle assessment (LCA) and target value design (TVD) to rapidly produce more sustainable building designs. By establishing site-specific sustainability targets and using dynamically-updating life cycle assessments, this research demonstrates that buildings can be designed to perform at higher environmental standards than those designed without a target in place. The research also offers unique opportunities to analyze the tradeoffs between design and operational decisions.
•Sustainable target value (STV) design combines LCA and target value design (TVD).•Building life cycle performance targets are developed for CO2, energy, H2O, and O3.•STV targets are based on the planet's ecological carrying capacity.•STV software tool is developed to assess building design environmental performance.•Design teams with STV designed more sustainable buildings than teams without.
Since their discovery as a substrate for ribonucleotide reductase (RNR), the role of thioredoxin (Trx) and glutaredoxin (Grx) has been largely extended through their regulatory function. Both ...proteins act by changing the structure and activity of a broad spectrum of target proteins, typically by modifying redox status. Trx and Grx are members of families with multiple and partially redundant genes. The number of genes clearly increased with the appearance of multicellular organisms, in part because of new types of Trx and Grx with orthologs throughout the animal and plant kingdoms. The function of Trx and Grx also broadened as cells achieved increased complexity, especially in the regulation arena. In view of these progressive changes, the ubiquitous distribution of Trx and the wide occurrence of Grx enable these proteins to serve as indicators of the evolutionary history of redox regulation. In so doing, they add a unifying element that links the diverse forms of life to one another in an uninterrupted continuum. It is anticipated that future research will embellish this continuum and further elucidate the properties of these proteins and their impact on biology. The new information will be important not only to our understanding of the role of Trx and Grx in fundamental cell processes but also to future societal benefits as the proteins find new applications in a range of fields.
Long‐distance dispersal is a key factor explaining the success of invasive alien species, particularly across oceanic islands. However, it is often not feasible to reliably measure long‐distance seed ...dispersal (LDD) over many kilometers in the field. Here, we used a three‐dimensional kinematic trajectory model (Computing Atmospheric Trajectory tool CAT) initiated on the basis of regional wind field data to assess the potential for LDD of a wind‐dispersed invasive tree, Spathodea campanulata (African tulip tree), across the Society Islands (French Polynesia, South Pacific Ocean) following its initial planting and spread on the island of Tahiti. The main objective of our study was to determine whether S. campanulata could be expected to spread naturally among islands. Atmospheric dynamics, seed terminal velocity, precipitation, and temperature of air masses were considered to assess the potential for LDD between oceanic islands, with the island of Tahiti serving as the island source for multiple, geographically distant invasions. Aerial trajectories of modeled S. campanulata seeds indicated that wind‐dispersed seeds originating from trees on the island of Tahiti could reach most of the Society Islands and disperse as far as 1364 km. This result suggests that Spathodea can be expected to spread naturally among the Society Islands. When rainfall events were modeled as causal agents of seed settlement, fewer seeds reached distant islands, but more seeds settled on the closest island (20 km away). Including effects of island topography (“barrier effects”) also resulted in more seeds settling on the closest island and fewer seeds reaching the most distant islands. Overall, our findings suggest that recent atmospheric models can provide valuable insights into LDD and invasion patterns of wind‐dispersed invasive species.
Aim: We studied how the abundance of the highly invasive fruit-bearing tree Miconia calvescens DC. influences seed dispersal networks and the foraging patterns of three avian frugivores. Location: ...Tahiti and Moorea, French Polynesia. Methods: Our study was conducted at six sites which vary in the abundance of M. calvescens. We used dietary data from three frugivores (two introduced, one endemic) to determine whether patterns of fruit consumption are related to invasive tree abundance. We constructed seed dispersal networks for each island to evaluate how patterns of interaction between frugivores and plants shift at highly invaded sites. Results: Two frugivores increased consumption of M. calvescens fruit at highly invaded sites and decreased consumption of other dietary items. The endemic fruit dove, Ptilinopus purpuratus, consumed more native fruit than either of the two introduced frugivores (the red-vented bulbul, Pycnonotus cafer, and the silvereye, Zosterops lateralis), and introduced frugivores showed a low potential to act as dispersers of native plants. Network patterns on the highly invaded island of Tahiti were dominated by introduced plants and birds, which were responsible for the majority of plant-frugivore interactions. Main conclusions: Shifts in the diet of introduced birds, coupled with reduced populations of endemic frugivores, caused differences in properties of the seed dispersal network on the island of Tahiti compared to the less invaded island of Moorea. These results demonstrate that the presence of invasive fruit-bearing plants and introduced frugivores can alter seed dispersal networks, and that the patterns of alteration depend both on the frugivore community and on the relative abundance of available fruit.
Ferns are the only major lineage of vascular plants that have nutritionally independent sporophyte (diploid) and gametophyte (haploid) life stages. However, the implications of this unique life cycle ...for fern community ecology have rarely been considered. To compare patterns of community structure between fern sporophytes and gametophytes, we conducted a survey of the ferns of the islands of Moorea and Tahiti (French Polynesia). We first constructed a DNA barcode library (plastid rbcL and trnH-psbA) for the two island floras including 145 fern species. We then used these DNA barcodes to identify more than 1300 field-collected gametophytes from 25 plots spanning an elevational gradient from 200 to 2000 m. We found that species richness of fern sporophytes conforms to the well-known unimodal (i.e., mid-elevation peak) pattern, reaching a maximum at ~1000–1200 m. Moreover, we found that fern sporophyte communities become increasingly phylogenetically clustered at high elevations. In contrast, species richness of fern gametophytes was consistent across sites, and gametophytes showed no correlation of phylogenetic community structure with elevation. Turnover of sporophyte and gametophyte communities was closely linked with elevation at shallow phylogenetic levels, but not at deeper nodes in the tree. Finally, we found several species for which gametophytes had broader ranges than sporophytes, including a vittarioid fern with abundant gametophytes but extremely rare sporophytes. Our study highlights the importance of including diverse life history stages in surveys of community structure, and has implications for the possible impacts of climate change on the distribution of fern diversity.
Despite islands contributing only 6.7% of land surface area, they harbor ~20% of the Earth’s biodiversity, but unfortunately also ~50% of the threatened species and 75% of the known extinctions since ...the European expansion around the globe. Due to their geological and geographic history and characteristics, islands act simultaneously as cradles of evolutionary diversity and museums of formerly widespread lineages—elements that permit islands to achieve an outstanding endemicity. Nevertheless, the majority of these endemic species are inherently vulnerable due to genetic and demographic factors linked with the way islands are colonized. Here, we stress the great variation of islands in their physical geography (area, isolation, altitude, latitude) and history (age, human colonization, human density). We provide examples of some of the most species rich and iconic insular radiations. Next, we analyze the natural vulnerability of the insular biota, linked to genetic and demographic factors as a result of founder events as well as the typically small population sizes of many island species. We note that, whereas evolution toward island syndromes (including size shifts, derived insular woodiness, altered dispersal ability, loss of defense traits, reduction in clutch size) might have improved the ability of species to thrive under natural conditions on islands, it has simultaneously made island biota disproportionately vulnerable to anthropogenic pressures such as habitat loss, overexploitation, invasive species, and climate change. This has led to the documented extinction of at least 800 insular species in the past 500 years, in addition to the many that had already gone extinct following the arrival of first human colonists on islands in prehistoric times. Finally, we summarize current scientific knowledge on the ongoing biodiversity loss on islands worldwide and express our serious concern that the current trajectory will continue to decimate the unique and irreplaceable natural heritage of the world’s islands. We conclude that drastic actions are urgently needed to bend the curve of the alarming rates of island biodiversity loss.
Polynesians introduced the tropical crop taro (Colocasia esculenta) to temperate New Zealand after 1280 CE, but evidence for its cultivation is limited. This contrasts with the abundant evidence for ...big game hunting, raising longstanding questions of the initial economic and ecological importance of crop production. Here we compare fossil data from wetland sedimentary deposits indicative of taro and leaf vegetable (including Sonchus and Rorippa spp.) cultivation from Ahuahu, a northern New Zealand offshore island, with Raivavae and Rapa, both subtropical islands in French Polynesia. Preservation of taro pollen on all islands between 1300 CE and 1550 CE indicates perennial cultivation over multiple growing seasons, as plants rarely flower when frequently harvested. The pollen cooccurs with previously undetected fossil remains of extinct trees, as well as many weeds and commensal invertebrates common to tropical Polynesian gardens. Sedimentary charcoal and charred plant remains show that fire use rapidly reduced forest cover, particularly on Ahuahu. Fires were less frequent by 1500 CE on all islands as forest cover diminished, and short-lived plants increased, indicating higher-intensity production. The northern offshore islands of New Zealand were likely preferred sites for early gardens where taro production was briefly attempted, before being supplanted by sweet potato (Ipomoea batatas), a more temperate climate-adapted crop, which was later established in large-scale cultivation systems on the mainland after 1500 CE.
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