Search

The stability of inverse nonpremixed oxygen (O2)/methane (CH4) coaxial jet flames near blowout limits in a model combustor is studied by analyzing signals for their local combustion phenomena using high-speed imaging and dynamic pressure. The power spectral analysis and the statistical analysis are conducted to delineate the stability of the inverse nonpremixed flames. Depending on the O2 to CH4 momentum flux ratio ((O/F)mom), two distinguished combustion phenomena which lead to different liftoff mechanisms are observed in the same burner configuration: the partial liftoff related to the aerodynamic mechanism and the local extinction related to the flame–turbulence interaction. The results of the power spectral density (PSD) show that on approaching the near-blowout limits, the local extinction or the partial liftoff occurs not in a specific frequency, but in a time-varying random distribution. The normalized root mean square (NRMS) based on the frame-integrated visible light signal (SVL) is found to be effective for quantifying the local extinction and the partial liftoff and particularly delineating the stability of the present inverse nonpremixed flames with the partial liftoff. [ABSTRACT FROM AUTHOR]

Urban ecological reserves are large green areas immersed within cities where native and exotic species of plants and animals coexist. Here, we examined the environmental features that facilitate the occurrence of nine species of native birds in an urban ecological reserve located within one of the largest cities in the world, Mexico City. We also searched for changes in occupancy rates among the three distinct climatic seasons that occur in central Mexico: warm-dry, rainy, and cold-dry. Using data collected during four years and multi-season occupancy models, we found that most of our study species prefer the urbanized sites that surround the reserve over the core conservation areas. This urban affinity can be explained by the diverse vegetation that prevails in such urban sites, which offers a high habitat heterogeneity that facilitates the presence of bird species with distinct ecological needs. In contrast, the reserve consists of a relatively homogeneous xerophytic scrubland where a few species of shrubs and small trees are dominant. We also detected seasonal changes in five species, with highest occupancy during the warm-dry season of each year, which coincides with both their breeding season and the driest period of the year. This finding indicates that these birds find in the reserve and surrounding urban areas enough food and water during this limiting season as well as safe nesting sites. Our study provides evidence that some native birds can become urban exploiters and that the benefits that they obtain from urban settings are greatest during their breeding season. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Competitive exclusion, a mechanism for local extinction of organisms, has been well established among taxonomically related species, including those within the same genus, family, or class in animal communities. This study, however, focuses on competitive exclusion that occurs across phyla, exemplified by the exclusion of a native insect by an invading exotic mammal, where food resources overlap. The hypothesis proposed in this study is that the small Indian mongoose (Urva auropunctata) has caused the local extinction of a burying beetle (Nicrophorus nepalensis) on Okinawa Is., Japan due to competition for carcasses of small vertebrates. To test this hypothesis, a comparison of beetle abundance was conducted between the area intensively controlled for mongoose and the area where mongoose control was weak or nonexistent. The former situated north of the boundary to prevent mongoose from crossing, and the latter located south of the boundary. To determine the user of carcasses on the forest floor, mouse carcasses were laid and their consumers were observed in each area. The results showed that the beetle abundance was clearly higher in the former than in the latter, and no beetles were collected where mongoose have never been controlled. The beetles often buried the mouse carcasses for their reproduction in the former, whereas in the latter, mongoose frequently consumed the mouse carcasses. These results provide evidence of competitive exclusion of the burying beetle by mongoose. This conclusion represents the first demonstration of competitive exclusion across phyla in an animal community. [ABSTRACT FROM AUTHOR]

Fireflies (Coleoptera, Lampyridae) are a globally threatened group of insects due to habitat loss and fragmentation, light pollution, climate change and pesticides. However, against all odds, some firefly populations persist in urbanized environments where all four of these factors are present simultaneously. In this work, we compiled several data sources to document the diversity of fireflies in the urbanized area of Morelia, characterize their current habitats, and determine the main stressors affecting these bioluminescent insects. We found seven genera and 26 species of fireflies (19 nocturnal, seven diurnal) associated with 32 urban, peri-urban and extra-urban areas; at least, 14 are new records for Michoacán, and the list for the state now includes nine genera and 41 species. Five additional sites were documented as extinction sites. We compared the characteristics of these five sites with those of the sites with extant populations. We found that in Morelia, fireflies are mainly associated with areas that have high to moderate proportions of vegetation cover, are near water bodies, have very gentle to moderate slopes, and are exposed to low levels of light pollution. In contrast, the extinction sites showed high proportions of artificial surfaces and high levels of light pollution. Because some fireflies are considered bioindicators of ecosystem integrity as they are associated to specific habitats, are highly diverse and due to their sensitivity to environmental changes, we consider that sites from Morelia's urban core and extinction sites show the highest levels of environmental degradation, threatening most fireflies and other insects living in the urban core with local extinction. At the same time, our results also suggest that implementing conservation strategies and sustainable planning for the urban development of Morelia in the short term could allow fireflies and other vital elements of the city's insect communities to persist for future generations. Restoration and conservation of green areas and nighttime environments are essential for biodiversity and human health, especially in intra-urban zones. [ABSTRACT FROM AUTHOR]

Phylogeographic patterns in large mammals result from natural environmental factors and anthropogenic effects, which in some cases include domestication. The grey wolf was once widely distributed across the Holarctic, but experienced phylogeographic shifts and demographic declines during the Holocene. In the 19th–20th centuries, the species became extirpated from large parts of Europe due to direct extermination and habitat loss. We reconstructed the evolutionary history of the extinct Western European wolves based on the mitogenomic composition of 78 samples from France (Neolithic‐20th century) in the context of other populations of wolves and dogs worldwide. We found a close genetic similarity of French wolves from ancient, medieval and recent populations, which suggests the long‐term continuity of maternal lineages. MtDNA haplotypes of the French wolves showed large diversity and fell into two main haplogroups of modern Holarctic wolves. Our worldwide phylogeographic analysis indicated that haplogroup W1, which includes wolves from Eurasia and North America, originated in Northern Siberia. Haplogroup W2, which includes only European wolves, originated in Europe ~35 kya and its frequency was reduced during the Holocene due to an expansion of haplogroup W1 from the east. Moreover, we found that dog haplogroup D, currently restricted to Europe and the Middle East, was nested within the wolf haplogroup W2. This suggests European origin of haplogroup D, probably as a result of an ancient introgression from European wolves. Our results highlight the dynamic evolutionary history of European wolves during the Holocene, with a partial lineage replacement and introgressive hybridization with local dog populations. [ABSTRACT FROM AUTHOR]

Gradual ocean warming combined with stronger marine heatwaves (MHWs) can reduce abundances of foundation species that control community structures, biodiversity, and ecosystem functioning. However, few studies have documented long‐term succession trajectories following the more extreme events that cause localized extinctions of foundation species. Here, we documented long‐term successional changes to marine benthic communities in Pile Bay, New Zealand, following the Tasman 2017/18 MHW, which caused localized extinctions of dominant southern bull kelp (Durvillaea sp.). Six years on, multiscale annual and seasonal surveys show no sign of Durvillaea recolonization. Instead, the invasive annual kelp (Undaria pinnatifida), rapidly colonized areas previously dominated by Durvillaea, followed by large changes to the understory community, as Durvillaea holdfasts and encrusting coralline algae were replaced by coralline turf. Between 3 and 6 years after the total loss of Durvillaea, smaller native fucoids colonized in high densities. Although Undaria initially colonized plots throughout Durvillaea's tidal range, later in the succession Undaria only retained dominance in the lower intertidal zone and only in spring. Ultimately, the tidal zone was slowly replaced by alternative foundation species, composed of different canopy‐forming brown seaweeds that dominated different intertidal elevations, resulting in a net increase in canopy and understory diversity. This study is a rare example of long‐term effects following an extreme MHW that caused extinctions of a locally dominant canopy‐former, but these events and their associated dramatic changes to community structures and biodiversity are expected to become increasingly common as MHWs continue to increase in strength, frequency, and duration. [ABSTRACT FROM AUTHOR]

Savanna plant communities are highly diverse, characterized by an open-canopy structure with rich herbaceous diversity, and maintained by frequent low-intensity fire and grazing. Due to habitat loss and fragmentation, savannas are globally threatened, with less than 1% of former oak savanna land cover found in the Midwestern United States remaining. In remnant oak savannas, loss of fire and grazing has led to woody encroachment and canopy closure over the past century with cascading consequences for the taxonomic composition. Whether these taxonomic changes can be broadly predicted using species functional traits (morpho-physio-phenological characteristics that impact the fitness of a species) is a key question. We ask whether the impacts of woody encroachment on herbaceous species can be predicted from species' abilities to persist (avoid extinction) and disperse (colonize new areas). Specifically, we pair persistence traits (e.g., clonality, belowground storage) and dispersal traits (e.g., seed mass, dispersal mode, flowering height) with a rare 60-year dataset from oak savannas in Wisconsin, USA to understand how the representation of these traits has changed in the herbaceous community over time. Over 60 years, change in species composition was explained both by dispersal abilities and persistence traits; small-seeded species reliant on unassisted dispersal and moderately clonal species experienced the greatest losses. These changes in functional composition are likely due to increased woody encroachment, which may impede propagule production and movement. Restoration efforts need to prioritize species that are dispersal limited and those that create fine fuels, which aid the persistence of fire-maintained open habitat savannas. [ABSTRACT FROM AUTHOR]

Background: Temperature, as one of the effective environmental stimuli in many aspects of species life and ecosystems, can affect amphibians in many ways. Knowing and predicting temperature change and its possible effects on the habitat suitability and movements of amphibians have led many researchers to use climate change scenarios and species distribution models (SDMs). One of the important remote-sensing products that received less attention of conservation biologists is the land surface temperature (LST). Due to the small difference between LST and air temperature, this component can be used to investigate and monitor the daily and seasonal changes of habitats. This study aims to investigate the seasonal trend of LST in the habitat suitability and connectivity of the critically endangered newt (Neurergus derjugini) in its small distribution range, using the MODIS LST time series (2003 to 2021) and with the help of SDMs, Mann–Kendall (MK) and Pettitt non-parametric tests. Results: In the last decade, the increasing trend of LST versus its decreasing trends is obvious. Based on MK and Pettitt tests, in the winter and spring, with the decrease in latitude of 35.45° and increase in longitude of 46.14°, the core populations which are located in the southeast have experienced an increase in temperature. Considering the period time of breeding and overwintering, the continuity of winter and spring can be effective on the survival of adult newts as well as larvae in the microclimate. Linkages with the highest current flow between core populations in the winter and summer are the most likely to be vulnerable. At the level of habitat, the increase in LST is proportional to the trend of thermal landscape changes, and all seasons have had an increase in LST, but in winter and summer, the largest area of the habitat has been involved. By continuing the current trend, many high-altitude southern habitats in Iran will be endangered, and the species will be at risk of local extinction. Conclusion: The increasing trend of temperature in all seasons such as winter will affect many adaptations of the species and these effects are mostly evident in the southern parts of its distribution range therefore, captive breeding and reintroduction are recommended for the populations of these areas. [ABSTRACT FROM AUTHOR]

Background: Ponerine ants are almost exclusively predatory and comprise many of the largest known ant species. Within this clade, the genus Neoponera is among the most conspicuous Neotropical predators. We describe the first fossil member of this lineage: a worker preserved in Miocene-age Dominican amber from Hispaniola. Results: Neoponera vejestoria sp. nov. demonstrates a clear case of local extinction—there are no known extant Neoponera species in the Greater Antilles. The species is attributable to an extant and well-defined species group in the genus, which suggests the group is older than previously estimated. Through CT scan reconstruction and linear morphometrics, we reconstruct the morphospace of extant and fossil ants to evaluate the history and evolution of predatory taxa in this island system. Conclusions: The fossil attests to a shift in insular ecological community structure since the Miocene. The largest predatory taxa have undergone extinction on the island, but their extant relatives persist throughout the Neotropics. Neoponera vejestoria sp. nov. is larger than all other predatory ant workers known from Hispaniola, extant or extinct. Our results empirically demonstrate the loss of a functional niche associated with body size, which is a trait long hypothesized to be related to extinction risk. [ABSTRACT FROM AUTHOR]

Local populations of marine benthic macro‐invertebrates with planktonic larvae are believed to be in source–sink relationships via larval dispersal in a regional population complex. Practically, such a region is definable only after connectivity of constituent local populations is explored. Numerical simulations abound for hydrodynamic connectivity by larvae between local/regional populations. Empirical studies have scarcely integrated inter‐local connectivity and intra‐local population dynamics into demographic connectivity analysis. I review the current research and indicate fundamental and technical problems to demonstrate that some source–sink systems in intertidal shores, which are most accessible among benthic habitats, are a good model. The challenge in benthic source–sink research comes from that existent local populations may not be self‐sustaining because of low larval self‐seeding rates and/or low benthos' survival rates and yet can persist as latent sinks. They may receive larvae leaking from sources at good‐quality habitat patches with stationary larval retention areas for self‐recruitment. On an intertidal sandflat in an estuary–coastal ocean region, Kyushu, Japan during 1979–2019, the population of a trochid gastropod with 3‐ to 9‐day larval duration became extinct and recovered. The extinction was caused by sediment destabilization by a callianassid shrimp population which increased in the early 1980s. The gastropod recovery was owing to the shrimp decline by stingray predation and the transport of larvae from some self‐sustainable populations with lower shrimp densities 30 km away. It was estimated that the gastropod population before the shrimp proliferation on that sandflat might be a latent sink requiring allochthonous larval subsidy due to epi‐benthic predation on juveniles. [ABSTRACT FROM AUTHOR]

Small patches of habitat for indigenous species that remain in developed landscapes are predicted to lose species over time as extinction debts are paid off and to become transformed by spillover from intensive land uses. In December 2020 we searched for plants of three inland South Island-endemic species of Lepidium (Brassicaceae; L. kirkii, L. sisymbrioides, and L. solandri) at previously known locations in Central Otago, the Waitaki Valley, the Mackenzie Basin, and Kura Tāwhiti (Castle Hill, North Canterbury). We recorded whether Lepidium populations remained and identified the vascular plant flora of each location. Lepidium kirkii was found at six of 14 locations where formerly known and at one new location, but numbered over 50 individuals at only one of these locations. Lepidium sisymbrioides was found at five of six locations visited, but we found fewer than four individuals at three of these locations. L. solandri was found at five of 12 formerly known locations in Central Otago (but numbered over 50 individuals at only one), at five of five formerly known locations on public land in the Mackenzie Basin, and at the one known location at Kura Tāwhiti. Exotic vascular plant species outnumbered native species at all but one Lepidium location in Central Otago and at Kura Tāwhiti, but not in the Mackenzie Basin, where there had been the least habitat loss and land-use intensification. Our results are consistent with theoretical predictions of more local plant extinctions at Lepidium locations, and greater transformation of their habitats, in landscapes dominated by intensive land uses and non-indigenous vegetation. We conclude that intensive ex situ and in situ management is now needed to avoid global extinctions of L. kirkii and L. sisymbrioides, and local extinctions of L. solandri at remaining Central Otago locations and at Kura Tāwhiti. We do not know whether landscape-scale processes still provide for the persistence of L. solandri and other dryland species in the Mackenzie Basin or whether intensive land use has already crossed ecological thresholds. [ABSTRACT FROM AUTHOR]

To determine the present-day community composition of siliceous Rhizaria (Radiolaria and Phaeodaria) in Norwegian fjords, plankton tows were conducted in south-western and northern Norwegian fjords in September 2016. The mean total abundance of radiolarians was 306 m–3 in the Sognefjord complex, which was the southern research site, and, in the north, 945 m–3 in Malangen and 89 m–3 in Balsfjord, both above the Arctic Circle. Sticholonche zanclea was the most abundant radiolarian in the Sognefjord complex and Malangen, accounting for 78–100% (mean 89%) of radiolarian abundance. The mean total abundance of phaeodarians was 1554 m–3 in the Sognefjord complex, 51 m–3 in Malangen and 11 m–3 in Balsfjord. Medusetta arcifera was the most abundant phaeodaria in the Sognefjord complex, accounting for >99% of phaeodarian abundance, but was absent in Malangen and Balsfjord, where Protocystis tridens accounted for >96% of phaeodarian abundance. The carbon biomass of S. zanclea and M. arcifera was 188 and 438 µg C m–3, respectively, which is similar to and 8.6 times higher than, respectively, that of phaeodarians >1 mm in the western North Pacific, suggesting that M. arcifera contributes to organic carbon transport in the Sognefjord complex. Amphimelissa setosa (Nassellaria, Radiolaria), which was a dominant species in the study area in 1982–83, was absent in the present study in all sampled fjords. This could have been caused by the approximately 2 °C increase in water temperature that has occurred since 1990 and can be taken as evidence of a climate-change-associated local temperature rise linked to the warming of advected Atlantic Water. [ABSTRACT FROM AUTHOR]

To date, only two Cherax species have been reported to occur in Italy, i.e., C. destructor Clark, 1936 and C. quadricarinatus (von Martens, 1868), both in the wild and in aquaculture farms. Therefore, we aimed to update their current status and distribution in Italian mainland and Sicily. In addition, we investigated the origin of their known populations, and their possible routes of invasion. In order to genetically characterize the Cherax populations occurring in Italian inland waters and aquaculture facilities, the barcode region of the mtDNA gene cytochrome oxidase subunit I was sequenced in the available specimens originating from an aquaculture facility and a museum collection. The sampling campaigns conducted in 2021 did not lead to the collection of any Cherax individuals in the sites where the species was formerly reported to occur. The recent failures to detect Cherax spp. from Italian inland waters might be due to the inability of the species to cope with the Italian climate, which is likely for C. quadricarinatus but less so for C. destructor, to the possible impact of the alien red swamp crayfish Procambarus clarkii (as well as its indirect impact i.e., the spread of the crayfish plague for which yabby is susceptible), which occurs in both the sites where C. destructor was reported in Italy, or to the burrowing habits of the species, which might lead to overlook their presence when present at low densities. In the light of the well-known impact of invasive crayfish and considering the scant knowledge about the current distribution and status of Cherax species in Italy, a regular monitoring of their possible presence is recommended. [ABSTRACT FROM AUTHOR]

To verify the effectiveness of continuous habitat-level monitoring survey in identifying species of conservation concern on a local scale, it has been conducted a continuous monitoring survey over five years for butterfly communities in a local area at the foot of Mount Fuji, a special zone of Fuji-Hakone-Izu National Park in Japan. The results showed that the butterfly community was divided roughly into two species groups (i.e. yearly constant appearing species and yearly sporadic appearing species). The former was characterized by relatively high density with more variability. While, the latter showed the reverse characteristics, suggesting that they are the species more prone to extinction in the area. Among the yearly sporadic appearing species, Red Listed species and the species with characteristics vulnerable to extinction (i.e. uni-voltines and/or larval food specialists) could be thought of particularly as species of conservation concern with high priority and urgency on a local scale. This is evidenced by the fact that, in the continuous monitoring survey conducted previously in nearly the same area, the Red Listed species thought to belong to yearly constant appearing species were all alive in the present survey, but the two Red Listed species thought to belong to yearly sporadic appearing species were already extinct between the both surveys. Consequently, results confirmed the effectiveness of continuous habitat-level monitoring survey in identifying species of conservation concern on a local scale. Thus, it has been recommended continuous monitoring surveys at a local (habitat) level in order to prevent the rapid progression of extinction of local populations. [ABSTRACT FROM AUTHOR]

Invasive snakes represent a serious threat to island biodiversity, being responsible for far-reaching impacts that are noticeably understudied, particularly regarding native reptiles. We analysed the impact of the invasive California kingsnake, Lampropeltis californiae--recently introduced in the Canary Islands--on the abundance of all endemic herpetofauna of the island of Gran Canaria. We quantified the density in invaded and uninvaded sites for the Gran Canaria giant lizard, Gallotia stehlini, the Gran Canaria skink, Chalcides sexlineatus, and Boettger's wall gecko, Tarentola boettgeri. We used spatially explicit capture-recapture and distance-sampling methods for G. stehlini and active searches under rocks for the abundance of the other two reptiles. The abundance of all species was lower in invaded sites, with a reduction in the number of individuals greater than 90% for G. stehlini, greater than 80% for C. sexlineatus and greater than 50% for T. boettgeri in invaded sites. Our results illustrate the severe impact of L. californiae on the endemic herpetofauna of Gran Canaria and highlight the need for strengthened measures to manage this invasion. We also provide further evidence of the negative consequences of invasive snakes on island reptiles and emphasize the need for further research on this matter on islands worldwide. [ABSTRACT FROM AUTHOR]

The Great Barrier Reef is a diverse ecosystem of outstanding universal value that is under an increasing level of cumulative threat. The status of biodiversity, particularly that of habitat-forming taxa is not known, and more data are needed to evaluate this. Here, we summarize scleractinian coral distribution records in the Lizard Island reef system from 1976 to 2020 to explore the persistence of the local species pool across 44 years. By undertaking replicated spatio-temporal biodiversity surveys (2011, 2015, 2017, 2020) at 14 sites and compiling published species records from this location (1976–2020), we determine that 368 species of hermatypic scleractinian coral have been recorded from Lizard Island and/or nearby reefs over the last 44 years. Two hundred and eighty-four of those species (77.2%) have ongoing records across this time period indicating temporal persistence at the local scale. However, 28 species (7.6%) that were reliably recorded prior to 2011 have not been recorded in subsequent years and may be at risk of local extinction. A further 31 species (8.4%) may be at risk of local range reduction as they have not been recorded at Lizard Island and/or at nearby reefs since 2015. The remaining 25 species (6.8%) were deemed taxonomically unreliable records. Fifty-three species are recorded from Lizard Island for the first time in the 2011–2020 surveys, however, further integrated taxonomic research is required to verify some of these records. At a site level, species diversity has been in a state of flux over the 2011–2020 period with significant declines in species richness notable from 2011 to 2017, and significant recovery from 2017 to 2020. Overall, this dataset indicates local extinction or local range reduction is a tangible risk for 59 species (16% of the species pool) in the Lizard Island region. Additional targeted searching for these species along with temporal monitoring of species abundance and size structure is warranted to better understand the status of coral biodiversity at this globally significant location. [ABSTRACT FROM AUTHOR]

Self-incompatible, non-clonal plant species are especially dependent on the activity of flower visitors for seed production. Therefore, populations of these plants are vulnerable to a reduced flower visitation rates, but also to increased isolation by extinction of local populations. To study how local populations of Centaurea scabiosa, a self-incompatible, bee-pollinated herb species changed over time in the region of Bonn, we collected historical population records in the area and investigated their current status. We found that more than half of the subpopulations mentioned in the literature between 1950 and 2012 (38 of 65) have since disappeared. Small populations were most vulnerable, whereas medium to large populations increased in size. In a second step, we studied visitation frequencies and achene production and weight across 14 extant populations. We found that both flower visitation frequency and achene production were positively related to population size. Achene weight was neither related to the frequency of flower visitors nor to achene production. These results clearly indicate that reduced pollen transfer and lower pollination rates may contribute to local extinction in small populations of Centaurea scabiosa. Overall our results call for an intensified monitoring of the populations of self-incompatible plant species. [ABSTRACT FROM AUTHOR]

Species losses and local extinctions are alarmingly common, frequently as a consequence of habitat destruction. Nevertheless, many intact habitats also face species losses, most likely due to environmental changes. However, the exact drivers, and why they affect some species more than others in apparently intact habitats, are still poorly understood. Addressing these questions requires data on changes in occurrence frequency of many species, and comparisons of the responses of those species to experimental manipulations of the environment. Here, we use historic (1911) and contemporary (2017) data on the presence–absence of 42 plant species in 14 seemingly intact Molinia meadows around Lower Lake Constance to quantify changes in occurrence frequency. Then, we performed a common‐garden experiment to test whether occurrence frequencies in 1911 and changes therein by 2017 could be explained by responses of the 42 species to nutrient addition and competition with the acquisitive generalist grass Poa pratensis. Within the 14 still intact Molinia meadows, 36 of the 42 species had declined since 1911. As expected, nutrient addition generally led to increased biomass production of the 42 target species, and competition with P. pratensis had a negative effect. The latter was stronger at high nutrient availability. The more frequent species were in 1911 and the more they declined in frequency between 1911 and 2017, the less above‐ground biomass they produced in our experiment. Competition with P. pratensis magnified this effect. Our work highlights that environmental change can contribute to local extinction of species in otherwise intact habitat remnants. Specifically, we showed that increased nutrient availability negatively affected formerly widespread Molinia‐meadow species in competition with P. pratensis. Our study thus identified a likely mechanism for the decline in occurrence frequency of species in the remaining Molinia meadows. [ABSTRACT FROM AUTHOR]

The turbulent counter-flow flame (TCF) has proven to be a useful benchmark to study turbulence-chemistry interactions, however, the widely observed bulk flow fluctuations and their influence on the flame stability remain unclear. In the present work, premixed TCFs are studied numerically using a Large Eddy Simulation (LES) method. A transported probability density function (pdf) approach is adopted to simulate the sub-grid scale (sgs) turbulence-chemistry interactions. A solution to the joint sgs-pdf evolution equation for each of the relative scalars is obtained by the stochastic fields method. The chemistry is represented using a simplified chemical reaction mechanism containing 15 reaction steps and 19 species. This work compares results with two meshing strategies, with the domain inside nozzles included and excluded respectively. A conditional statistical approach is applied to filter out the large scale motions of the flame. With the use of digital turbulence, the velocity field in the flame region is well reproduced. The processes of local extinction and re-ignition are successfully captured and analysed together with the strain rate field, and local extinctions are found correlated to the turbulent structures in the reactant stream. The predicted probability of localised extinction is in good agreement with the measurements, and the influence of flame stoichiometry are also successfully reproduced. Overall, the current results serve to demonstrate the capability of the LES-pdf method in the study of the premixed opposed jet turbulent flames. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Threatened Taxa is the property of Wildlife Information Liaison Development and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The biology and seasonal phenology of Aacanthocnema dobsoni (Froggatt) were studied at a single site in Victoria over a 2 year period between 2013 and 2015. This species is monophagous on the dioecious host, Allocasuarina verticillata (Lam.) L. Johnson (Casuarinaceae). Laboratory studies found that females attained reproductive maturity 24 h post‐eclosion, lived for 28.6 ± 2.8 (mean ± SE) days and laid 182 ± 23 (mean ± SE) eggs each. Egg development was most rapid at 26 °C, ceased below 7 °C and above 33 °C; hatching required 188 degree‐days. Nymphs could not be reared to adulthood on excised host branchlets maintained under controlled conditions, so no developmental data were obtained for these life stages. Seasonal phenology data revealed pronounced developmental asynchrony, i.e. with overlapping generations and multiple life stages occurring simultaneously. Three generations per year were observed, and there was no evidence of either developmental (egg and nymph) or reproductive diapause. A 4 day heat wave in January 2014 drastically reduced psyllid abundance at the study site and the size of the adults that eclosed from the surviving nymphs. These smaller adults produced substrate‐borne vibrational signals with altered characteristics, i.e. with significantly higher intensities and power. The altered signals might have facilitated communication over longer distances and increased mate finding opportunities when populations were low. The abundance of adults had recovered to preheat wave levels 3 months after the heat wave. High fecundity, multivoltinism and effective mate attraction signalling are life history traits that may mitigate against localised extinction of populations as a consequence of extreme weather events. [ABSTRACT FROM AUTHOR]

The anthropic effect associated with worldwide European settlements over the last 500 years has caused dramatic environmental changes, modified regional patterns of biodiversity, and often led to local or complete extinctions. The sigmodontine rodents of Bahía Samborombón (Humid Pampas, central-eastern Argentina) constitute a good case study: a late Holocene archaeological site allowed us to compare a pre-European settlement assemblage (12 species) with the extant one (nine species). We used linear morphometrics (16 cranial and ten mandibular measurements) to assess interspecific morphological variations of the masticatory apparatus in relation to dietary habits for each assemblage. Even though sigmodontines have a tendency towards omnivory, groups based on dietary preference only overlapped partially. Size was one of the main variables involved in niche segregation, and shape characteristics such as rostrum elongation or mandible robustness were linked to different diets. We found that a combination of dietary preference and size was associated with extinctions. The main morphospace change between the two assemblages was related to the local extinction of the three greater insectivores and the smallest graminivore, located towards the center of the assemblage's morphospace. An insectivore was incorporated, involving no significant changes in the general morphospace. Graminivores and larvivores were not affected. Our study sheds light on the causes of local extinctions of small mammals at the Humid Pampas, a phenomenon that had never been studied from an ecomorphological approach. [ABSTRACT FROM AUTHOR]

Copyright of Hacquetia is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heterogeneity in quantity and quality of resources provided in the urban matrix may mitigate adverse effects of urbanization intensity on the structure of biotic communities. To assess this we quantified the spatial variation in butterfly richness and abundance along an impervious surface gradient using three measures of urban matrix quality: floral resource availability and origin (native vs. exotic plants), tree cover, and the occurrence of remnant habitat patches. Butterfly richness and abundance were surveyed in 100 cells (500 × 500 m), selected using a random‐stratified sampling design, across a continuous gradient of imperviousness in Melbourne, Australia. Sampling occurred twice during the butterfly flight season. Occurrence data were analyzed using generalized linear models at local and mesoscales. Despite high sampling completeness, we did not detect 75% of species from the regional species pool in the urban area, suggesting that urbanization has caused a large proportion of the region's butterflies to become absent or extremely rare within Melbourne's metro‐area. Those species that do remain are largely very generalist in their choice of larval host plants. Butterfly species richness and abundance declined with increasing impervious surface cover and, contrary to evidence for other taxa, there was no evidence that richness peaked at intermediate levels of urbanization. Declines in abundance appeared to be more noticeable when impervious surface cover exceeded 25%, while richness declined linearly with increasing impervious surface cover. We find evidence that the quality of the urban matrix (floral resources and remnant vegetation) influenced butterfly richness and abundance although the effects were small. Total butterfly abundance responded negatively to exotic floral abundance early in the sampling season and positively to total floral abundance later in the sampling season. Butterfly species richness increased with tree cover. Negative impacts of increased urbanization intensity on butterfly species richness and abundance may be mitigated to some extent by improving the quality of the urban matrix by enhancing tree cover and the provision of floral resources, with some evidence that native plants are more effective. [ABSTRACT FROM AUTHOR]

Summary: African White-backed Vultures were recently uplisted to 'Critically Endangered' by IUCN due to declines across their range. Poisoning is widely accepted as the major reason for these declines. Botswana supports a high number of this species (breeding pairs > c.1,200), but as yet no published information exists on their breeding success in the country. However, mass poisonings within Botswana and neighbouring countries have killed thousands of White-backed Vultures in recent years. We therefore expected that nesting numbers may have declined in this region if these poisoning events killed local breeding birds. We used information from aerial surveys conducted between 2006 and 2017 in Khwai and Linyanti, two important breeding areas for this species in north-central Botswana, to determine if there was any change in nesting numbers and breeding success of White-backed Vultures. Results showed an overall 53.5% decline in nesting numbers, with a greater decline in Linyanti than in Khwai. In both areas, breeding success was significantly lower in 2017 than it was 10 ten years earlier. We recommend that similar repeat surveys are continued to provide greater confidence in the trends of both nesting numbers and breeding performance. Population viability analysis suggested that if the productivity levels detected in 2017 were a true indication of current productivity levels for this population, and if recent high poisoning rates continue, this population could be extirpated from the area in the next 13 years. [ABSTRACT FROM AUTHOR]

The continued decline in the small breeding population of southern elephant seals Mirounga leonina at Gough Island (40°19′S, 9°57′W) over a period of 46 years (1973–2019) signals the likely extirpation of the species at the northernmost extent of its breeding range in the Southern Ocean. The estimated number of births declined from a high (n = 38) in 1975 to a low (n = 2) in 2019, a 95% reduction at an average decrease of 2.15% per annum. The estimated mean time to extinction of this population from a linear regression model is 2 years (95% CI: 0–23 years). This decline is consistent with observed or forecasted population trends of some other marine top predators at the northern extent of their breeding ranges in the Southern Ocean; adding to the prevailing evidence that environmental change is the most plausible hypothesis explaining the range reduction of these marine species limited by a paucity of breeding grounds. [ABSTRACT FROM AUTHOR]

Understand the spatial distribution of wildlife roadkill is necessary to design mitigation measures minimizing damage to the fauna and the human population. Thus, we aimed to analyze the spatial distribution of wildlife roadkill in the Brazilian savanna ("Cerrado") to test whether roadkill hotspots match between the studied animal groups. We collected data of wildlife roadkill over a year in the southwest region of the state of Goiás, Brazil. To understand the distribution of roadkill on highways and to identify the aggregation hotspots, we used the modified two-dimensional Ripley K test and the two-dimensional hotspot identification analysis. We detected that birds and mammals have different aggregation points. These points may vary when the two groups are analyzed together or when species with greater abundance are removed from the analyses. Hence, we concluded that using generalist approaches including several species, are not enough, and can lead to erroneous conclusions. Therefore, it is necessary that the analyses be done in groups. [ABSTRACT FROM AUTHOR]

Understanding the impacts of invaders on plant taxonomic diversity and community stability is significant for understanding the mechanisms underlying successful invasion. This study explored the impacts of the invasive plant Canada goldenrod (Solidago canadensis L.; goldenrod hereafter) with different degrees of invasion on plant taxonomic diversity and community stability by conducting a comparative study in eastern China. Degree of invasion was divided into the following categories, low (<35%, LDI), moderate (35–75%, MDI), and high (>75%, HDI), on the basis of the relative abundance of goldenrod in the invaded plant communities. Plant diversity, dominance, richness, and plant community stability noticeably decreased under HDI but plant diversity and dominance dramatically increased under LDI compared with the adjacent uninvaded plant communities. Plant diversity, dominance, richness, and community stability markedly declined as the degree of goldenrod invasion increased in the invaded plant communities. The greater plant diversity and dominance observed under LDI may be primarily driven by the passenger effects rather than a driving force of the presence of goldenrod. The greater competitive superiority of goldenrod over coexisting native plants under HDI might allow for invasion and enhance the risk of stochastic local extinction of several native species. A significantly positive diversity‐stability relationship was observed, which may explain the underlying mechanisms for the decreased plant community stability and drastic decline in plant diversity under HDI. Accordingly, the degree of invasion of goldenrod plays an important role in the variation of plant taxonomic diversity and community stability in eastern China. [ABSTRACT FROM AUTHOR]

Accelerated anthropogenic impacts and climatic changes are widely considered to be responsible for unprecedented species extinction. However, determining their effects on extinction is challenging owing to the lack of long-term data with high spatial and temporal resolution. In this study, using historical occurrence records of 11 medium- to large-sized mammal species or groups of species in China from 905 BC to AD 2006, we quantified the distinctive associations of anthropogenic stressors (represented by cropland coverage and human population density) and climatic stressors (represented by air temperature) with the local extinction of these mammals. We found that both intensified human disturbances and extreme climate change were associated with the increased local extinction of the study mammals. In the cold phase (the premodern period of China), climate cooling was positively associated with increased local extinction, while in the warm phase (the modern period) global warming was associated with increased local extinction. Interactive effects between human disturbance and temperature change with the local extinction of elephants, rhinos, pandas, and water deer were found. Large-sized mammals, such as elephants, rhinos, and pandas, showed earlier and larger population declines than small-sized ones. The local extinction sensitivities of these mammals to the human population density and standardized temperature were estimated during 1700 to 2000. The quantitative evidence for anthropogenic and climatic associations with mammalian extinction provided insights into the driving processes of species extinction, which has important implications for biodiversity conservation under accelerating global changes. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) methods are increasingly used to detect aquatic organisms. To optimize survey efficiency in natural environments, it is necessary to understand the seasonal change in eDNA concentrations of target species and identify the season and environmental conditions in which eDNA concentrations are highest. Recently, eDNA methods have been developed to detect aquatic plant species, but the seasonal change in the eDNA concentrations remains uninvestigated. Many aquatic plants undergo considerable changes in abundance, size, and shape throughout the year. Therefore, their eDNA concentration may change along with their phenology. We investigated the seasonal change in the eDNA concentration of an aquatic submerged species, Hydrilla verticillata , in agricultural ponds in Japan by measuring the eDNA concentration of H. verticillata from 5 ponds 5× in a year. This species has a dormant period during winter and a growth period from spring to autumn. The eDNA concentrations were higher during the growth period than during the dormant period. Management and conservation surveys that use eDNA for species detection should be done when eDNA concentrations are highest to maximize detection probabilities and therefore survey efficiency. [ABSTRACT FROM AUTHOR]

Plant communities across multiple climate zones are at risk of invasive species. Understanding the effects of invasive alien species on both the taxonomic and functional diversities of plant communities in different climate zones enables insight into the mechanisms underlying successful invasions. This study investigated the effects of Erigeron canadensis at different degrees of invasion on both the plant taxonomic and functional diversities in the Chinese zones of Jinan (warm temperate climate) and Zhenjiang (north subtropical climate). A high degree of E. canadensis invasion resulted in a stronger decrease of plant diversity compared to a light degree of E. canadensis invasion. This may be because E. canadensis invasion can lead to a decrease in the number of native species via competition and subsequent local extinction. A high degree of E. canadensis invasion increased the Rao's quadratic entropy of plant height and ground cover. This may be because both the plant height and ground cover of E. canadensis and natives increased with increasing degree of E. canadensis invasion. The number of plant species in plant communities was lower in Jinan than in Zhenjiang. This is presumably because E. canadensis grows better in Jinan than in Zhenjiang and therefore, rare species are more likely to go extinct there. A small number of functional diversity indices of Jinan plant communities were higher than those of Zhenjiang. This may be due to the higher value of functional traits of E. canadensis in Jinan. [ABSTRACT FROM AUTHOR]

The northern portion of the Atlantic Forest, namely Pernambuco Endemism Center (PEC), faces an extreme level of forest loss, with only 2% of its original forest remaining. In the PEC, mesocarnivores are the only remaining carnivores and, among them, the ocelot and South American coati present a poorly known or even ignored distribution. Our goal is to provide an overview of the current distribution and conservation status of both species in the PEC through camera trap survey, review of published scientific literature and a search for voucher specimens in mammal collections. Our data confirm the presence of the ocelot and the South America coati in the PEC. The ocelots were mainly recorded in fragments smaller than 12 km2, suggesting they might access the monoculture matrix and anthropogenic areas. The few recent records of coatis suggest a worse scenario, predicting an imminent local extinction. The PEC has witnessed a historical continued deforestation, which has reduced the remaining fragments and contributed to the accentuated decline of both species populations. Nevertheless, these Atlantic Forest remnants are paramount to supporting relict populations of mesocarnivores in the PEC, and their maintenance and connectivity should be a conservation priority. [ABSTRACT FROM AUTHOR]

The Pyrenean brown bear Ursus arctos population in the mountains between France and Spain is one of the smallest and most threatened populations of large carnivores in Europe. We assessed trends in brown bear habitat use in the Pyrenees and investigated the underlying environmental and anthropogenic drivers. Using detection/non-detection data collected during 2008–2014 through non-invasive methods, we developed dynamic occupancy models, accounting for local colonization and extinction processes. We found two non-connected core areas of occupancy, one in the west and the other in the centre of the Pyrenees, with a significant decrease in habitat use overall during 2008–2014. We also found a negative correlation between human density and bear occupancy, in agreement with previous studies on brown bear habitat suitability. Our results confirm the Critically Endangered status of the Pyrenean population of brown bears. [ABSTRACT FROM AUTHOR]

Understanding the relative impact of climate change and land cover change on changes in avian distribution has implications for the future course of avian distributions and appropriate management strategies. Due to the dynamic nature of climate change, our goal was to investigate the processes that shape species distributions, rather than the current distributional patterns. To this end, we analyzed changes in the distribution of Eastern Wood Pewees (Contopus virens) and Red‐eyed Vireos (Vireo olivaceus) from 1997 to 2012 using Breeding Bird Survey data and dynamic correlated‐detection occupancy models. We estimated the local colonization and extinction rates of these species in relation to changes in climate (hours of extreme temperature) and changes in land cover (amount of nesting habitat). We fit six nested models to partition the deviance explained by spatial and temporal components of land cover and climate. We isolated the temporal components of environmental variables because this is the essence of global change. For both species, model fit was significantly improved when we modeled vital rates as a function of spatial variation in climate and land cover. Model fit improved only marginally when we added temporal variation in climate and land cover to the model. Temporal variation in climate explained more deviance than temporal variation in land cover, although both combined only explained 20% (Eastern Wood Pewee) and 6% (Red‐eyed Vireo) of temporal variation in vital rates. Our results showing a significant correlation between initial occupancy and environmental covariates are consistent with biological expectation and previous studies. The weak correlation between vital rates and temporal changes in covariates indicated that we have yet to identify the most relevant components of global change influencing the distributions of these species and, more importantly, that spatially significant covariates are not necessarily driving temporal shifts in avian distributions. We analyzed changes in the distribution of Eastern Wood Pewees and Red‐eyed Vireos from 1997 to 2012 using dynamic correlated‐detection occupancy models. Temporal variation in climate explained marginally more deviance than temporal variation in land cover. The weak correlation between temporal changes in covariates and changes in bird distributions indicated that spatially significant covariates are not necessarily driving temporal shifts in avian distributions. [ABSTRACT FROM AUTHOR]

Widespread in the past, the Griffon Vulture (Gyps fulvus) has disappeared in most of Europe (including Bulgaria) in the 20th century. Although this species was reported from Southwestern Bulgaria in the area of Rila and Pirin it became locally extinct. In the end of 20th century it was breeding only in Eastern Rhodopes. With the local reintroduction of the species in Kresna Gorge since 2010, the high mountain pastures and cliffs regained their role of refuge for the Griffon Vulture mainly in summer. Here, we report and analyze the home range and seasonal presence of the species in Rila National Park, Pirin National Park and Rilski Manastir Nature Park. Home range analysis was based on data received from 8 birds tracked by GPS/GSM transmitters in Southwestern Bulgaria. The obtained results (Max. Daily distance = 195.3 ± 51.1 km; Home-range 95% kernel = 238 ± 207.5km² and core area 50% kernel = 6.5 ± 5.4 km²) indicated that these birds almost exclusively roost and feed in the already established Griffon Vulture colonies or join the seasonal gatherings of conspecifics, which are usually found within a zone of 15 km radius from a complex of feeding site or abundant easy accessible food in close proximity to suitable roosting places. Strategically placed and permanently supplied vulture feeding stations in close proximity of roosting sites, may concentrate large numbers of Griffon Vultures in relatively small and controlled areas. This, in combination with implementation of site based conservation activities such as the creation of Vulture Safe Areas, the impact of any, otherwise, hardly controlled and large-scale threats, such as poisoning and electrocution can be buffered. Rila and Pirin National Parks as well as Rilski Manastir Nature Park are recommended for management, adapted to the Vulture Safe Areas concept. [ABSTRACT FROM AUTHOR]

Widespread in the past, the cinereous vulture has disappeared in most of Europe (including Bulgaria) in the twentieth century. Surviving nucleus remained only in Spain, Greece, Ukraine and the Caucasus. The species is considered extinct as nesting in Bulgaria yet within the Red Data Book in 1985. Despite occasional observations in the country and frequent presence and even sporadic nesting of solitary pairs in Eastern Rhodopes Mts., the cinereous vulture's Balkan Peninsula population (only one colony of 20-30 pairs in NE Greece) shows inability to increase further, disperse and reestablish naturally. This justifies the need to assist creation of new and more nesting sites to ensure long-term conservation of the species, based on local reintroduction in Bulgaria. After the success with the local reintroductions of the griffon vulture since 2010 in the Kresna Gorge and different places along the Balkan Mountains the conservation community in Bulgaria was encouraged to further proceed with the exploration and planning of reintroduction and conservation activities for the cinereous vulture. Herewith assessment of the chosen territories for reintroduction is presented and recent best sites in Bulgaria identified. [ABSTRACT FROM AUTHOR]

Currently, there is little information on the high mountain species' response to the climate change in Iran, and it seems that these species are significantly affected by the climate change. In the current research, the spatial vulnerability of Caspian snowcock (Tetraogallus caspius) to the climate change in Chaharmahal and Bakhtiari province was predicted using the ensemble modelling approach, based on seven species distribution models. According to the findings, about 19.43% of the province was estimated to be the suitable habitat of Caspian snowcock. The variables of annual precipitation (23.23%), annual temperature range (21.82%), human footprints (15.77%) and slope (14.46%) had the highest contributions to the model. Findings also showed that about 12.9-32.28% of the suitable habitats might be lost by 2050 due to the climate change, based on the two scenarios of increased greenhouse gases (RCP4.5 and RCP8.5) and the HadGEM2-CC model. At the same period, it is expected that the suitable habitats of the Caspian snowcock in the low altitude areas would be lost. Additionally, due to the climate change, some populations, especially in the far southern regions of the province, will undergo local extinction or may be completely isolated. Findings of this research can be, therefore, useful for adopting more appropriate approaches in order to manage and protect the Caspian snowcock populations in the country. [ABSTRACT FROM AUTHOR]

Many wildlife populations are either naturally, or as a result of human land use, patchily distributed in space. The degree of fragmentation—specifically the remaining patch sizes and habitat configuration—is an important part of population dynamics. Demographic stochasticity is also likely to play an important role in patchy habitats that host small local populations. We develop a simulation model to evaluate the significance of demographic stochasticity and the role fragmentation plays in the determination of population dynamics and the risk of extinction of populations on habitat patches. Our model is formulated as a Markov‐chain stochastic process on a finite, spatially explicit array of patches in which probability of successful dispersal is a function of interpatch distance. Unlike past work, we explicitly model local population dynamics and examine how these scale up to the entire population. As a test case, we apply the model to the American pika (Ochotona princeps) population living on the ore dumps in the ghost mining town of Bodie, California. This population has been studied nearly continuously for over four decades and has been of conservation concern as the southern half of the population declined precipitously beginning in 1989. Our model suggests that both the specific configuration of habitat and landscape heterogeneity are necessary and sufficient predictors of the eventual extinction of the southern constellation of patches. This example has important implications, as it suggests that fragmentation alone can lead to regional extinctions within metapopulations. [ABSTRACT FROM AUTHOR]

Changes in species distributions through local extinction and colonization events are a major consequence of climate change. The mechanisms underlying these processes, however, are yet to be fully understood.We investigate the effects of climatic suitability and local rarity on local extinction and colonization of British birds. We test the hypothesis that local extinction and colonization on decadal scales are driven by both climatic suitability and the prevalence of the species within an area and that the balance between these two is affected by species traits.We use spatially explicit conditional autoregressive models to determine the effect size of local rarity and climatic suitability (extracted from climate envelope models) on local extinction and colonization events. We then use phylogenetically constrained, generalized least‐square models to estimate the association of extinction and colonization predictors with body mass, clutch size and national range of each species.Both local rarity and climatic suitability of an area contributed to local extinctions and colonizations, but the importance of these predictors varied between species. This interspecific variation was explained, in part, by species traits, in particular national range, which influenced the importance of local rarity and climatic suitability to both local extinction and colonization.These results further our knowledge of the mechanisms underlying changes in species occupancy due to climate change. This can inform predictive models as well as contribute to more focussed avian conservation efforts. This article shows how the local rarity of a species and the climatic suitability of an area contribute to local extinction and local colonization in the British avifauna. It is shown, for the first time, how the importance of these abiotic drivers varies with species traits, specifically national range. [ABSTRACT FROM AUTHOR]

The two-stage combustion, local extinction, and flame-edge oscillations have been observed in single-droplet combustion tests conducted on the International Space Station. To understand such dynamic behavior of initially enveloped diffusion flames in microgravity, two-dimensional (axisymmetric) computation is performed for a gaseous n-heptane flame using a time-dependent code with a detailed reaction mechanism (127 species and 1130 reactions), diffusive transport, and a simple radiation model (for CO2, H2O, CO, CH4, and soot). The calculated combustion characteristics vary profoundly with a slight movement of air surrounding a fuel source. In a near-quiescent environment (≤ 2 mm/s), with a sufficiently large fuel injection velocity (1 cm/s), extinction of a growing spherical diffusion flame due to radiative heat losses is predicted at the flame temperature at ≈ 1200 K. The radiative extinction is typically followed by a transition to the “cool flame” burning regime (due to the negative temperature coefficient in the low-temperature chemistry) with a reaction zone (at ≈ 700 K) in close proximity to the fuel source. By contrast, if there is a slight relative velocity (≈ 3 mm/s) between the fuel source and the air, a local extinction of the envelope diffusion flame is predicted downstream at ≈ 1200 K, followed by periodic flame-edge oscillations. At higher relative velocities (4 to 10 mm/s), the locally extinguished flame becomes steady state. The present 2D computational approach can help in understanding further the non-premixed “cool flame” structure and flame-flow interactions in microgravity environments. [ABSTRACT FROM AUTHOR]

Global and local environmental changes lead to frequent plant extinctions many of which occur in man-made habitats such as agricultural fields. Plant traits and site conditions modify risks of extinction, but strength and sense of their effect are not known yet. Here, we present a long-term survey of population sizes for Mediterranean annual plants that we revisited 20 years after their first record to evaluate climate, population size, traits and habitat requirements as drivers of local extinctions. Small populations had an increased probability of extinction in our data-set. Our analyses revealed that seed production and survival of seeds in the soil seed bank decreased extinction rate, whereas plant size increased extinction probability. Mean annual temperature increased extinction rates of annual plants in cereal fields. We discuss these effects as a response to recent and ongoing habitat changes, and discuss how traits may be used to guide conservation practices in the face of local extinctions. [ABSTRACT FROM AUTHOR]

Aim: Large-scale biodiversity patterns are often discussed in the context of 'out of the tropics' (OTT) dynamics and/or tropical niche conservatism (TNC), but empirical evidence of these processes remains very limited. The aim of this study was to infer diversification processes and mechanisms of Cenozoic diversity dynamics using woody angiosperms. Location: East Asian continental islands and global. Time period: Cenozoic. Major taxa studied: Woody plants. Methods: We compiled Cenozoic fossil and modern records for woody angiosperm genera to reconstruct biodiversity patterns. To evaluate the relative importance of TNC and OTT, we investigated extinction/survival patterns and latitudinal range dynamics for each genus, in combination with their clade age (mean family age), cold tolerance and per-genus species richness. Results: We found diversity decreasing with latitude in modern-day flora, but not in the warmer periods of the Neogene and Palaeogene. The percentage of genera surviving decreased with latitude through the Cenozoic. Older genera with less cold tolerance and/or species-poor genera went extinct locally at high latitudes in response to post-Pliocene global cooling. Evolutionarily younger temperate genera dispersed from the extratropics to lower latitudes and the Southern Hemisphere after the Neogene. Main conclusions: The latitudinal diversity gradient (LDG) has rapidly steepened post-Pliocene through: (a) selective extinction in higher latitudes of old, less-diversified tropical genera with low freezing tolerance, and (b) equatorward distributional shift of temperate genera. Both these processes were driven by the high-latitude cooling. Such major roles of TNC and OTT, wherein temperate genera in the Northern Hemisphere expanded through the tropics into higher latitudes of the Southern Hemisphere across climatic boundaries without losing their temperate presence, are in contrast to OTT processes in marine systems. Cenozoic patterns of terrestrial woody angiosperm biodiversity indicate the importance of TNC and high-latitude processes, including the extinction of tropical genera and range contraction or shift of temperate genera. [ABSTRACT FROM AUTHOR]

Two major challenges in studying the impacts of exotic invasive species on native species are identifying mechanisms of displacement and replacement and the lack of long-term population studies in these systems. A solution for the first is to study invasive and native congeners that occupy the same niche. A solution for the second is to study many populations for one year instead of one population for many years. We studied the invasion biology of the invasive European paper wasp Polistes dominula and its native congener the Northern paper wasp P. fuscatus, two species which compete for similar resources. We tracked the demography of the two wasps at sites in the northeastern United States. We found that the survival of P. dominula to the reproductive period in August was three times that of P. fuscatus, across all sites. The reproductive output of P. fuscatus declined in direct proportion to the percentage of P. dominula nests at the site. P. fuscatus nests at uninvaded sites had three times the nest cells of those at the most invaded sites. These findings suggest a positive feedback cycle in the establishment of P. dominula, in which the invasive wasp drives population declines in the native that in turn allow P. dominula to further establish. This system provides an example of a possible extinction vortex caused by competitive exclusion of a species by its invasive congener. [ABSTRACT FROM AUTHOR]

Zerynthia cassandra is a butterfly endemic to the Italian peninsula. It was recently recognized as a sister species of Zerynthia polyxena. Z. cassandra is oligophagous as it feeds on a very restricted number of toxic plants belonging to the genus Aristolochia: Aristolochia pallida and A. rotunda. The paper reports the results of a research on the ecology of this species which was studied in the natural reserve "Stagni di Lungavilla" (Northern Italy) where the butterfly was living in a small patch of grassy vegetation bordered by a ditch at the margins of a pond. Z. cassandra develops one generation a year. Oviposition occurred in April. Eggs were mainly laid on the lower side of A. rotunda blades. The height of eggs from the ground depended on climatic trends, which affected the host plant phenology. Eggs mortality was mainly due to consumption of leaves by snails (Cepaea nemoralis) and slugs (Arion sp.). Larvae completed their development from April to May, while chrysalises were the aestivating and overwintering stage. Females did not lay eggs on host plants when they were part of the undergrowth. A decline of the butterfly due to habitat changes was recorded during the research (2001-2005). According to information coming from local butterfly watchers the butterfly used to be quite common in the natural reserve until 70’s. Its decline was caused by agricultural intensification and the natural evolution of vegetation towards woodlands, which gradually reduced the host plant density, so making the habitat unsuitable and causing the local extinction of the butterfly. [ABSTRACT FROM AUTHOR]

Strong social structuring within a population can confer fitness advantages to group members, but may also affect the ability of a population to recover from local extinctions. Opportunities to evaluate the dynamics of the collapse of a sub-population on a vertebrate population in the wild are rare, requiring a crash during a long-term study of marked individuals. Endangered long-tailed bats Chalinolobus tuberculatus, which are members of the widespread family Vespertilionidae, live in closed social groups as evidenced by non-random associations of individuals and a low degree of mixing among colonies. During a 19-year mark-recapture study of long-tailed bats in the Eglinton Valley, New Zealand, one colony of bats collapsed over a 2-year period in which numbers of introduced predators were high. We investigated individual- and colony-level implications of this local extinction event. Survivors (11 known) were assimilated into the neighbouring colony during and immediately after the collapse, but retained higher association rates with individuals from their former colony. The neighbouring colony gradually extended its roosting range into habitat formerly occupied by the extinct colony. Acceptance of individuals into other colonies demonstrates resilience of highly structured vertebrate populations to local crashes. [ABSTRACT FROM AUTHOR]

An increasing number of studies have forecast the potential responses of marine life to future climate change. This study predicts how the distributional range of temperate and tropical worm reefs (WRs) might respond to climate and environmental changes (CECs). Compared with current distributions, the tested hypotheses were: (i) under a low CO2 concentration and active atmospheric carbon capturing scenario (RCP2.6), both tropical and temperate WRs will maintain their current distributions and face only slight multi-directional biogeographic changes along the century; and (ii) under a high CO2 concentration scenario (RCP8.5) WRs will shift toward higher latitudes, with marked changes for tropical species and slight changes for temperate species, specifically at the end of the 21st century. The hypotheses were tested using species distribution modelling, and exploratory statistical analyses were performed to tune model settings. Under scenario RCP2.6, in the middle of the century, areas of suitable habitat are predicted to slightly increase for the temperate WRs and conversely contract for tropical WRs. At the end of the century, multi-directional shifts without range retraction were predicted for both species, but tropical WRs showed major changes in their distribution. Under scenario RCP8.5 and throughout the century, multi-directional shifts increased the areas of suitable habitat for temperate WRs, whereas tropical WRs experienced shifts toward high latitudes and significant retraction at low latitudes. Results indicate that biogeographic range shifts are idiosyncratic for temperate and tropical WRs depending on the CECs scenarios considered. [ABSTRACT FROM PUBLISHER]

Context: Conversion of landscapes is widely associated with loss of biodiversity. While there are several competing hypotheses for the local extinction of species in developed landscapes, experimental approaches are seldom applied to elucidating mechanisms. Objectives: In this study, we focus on the habitat degradation hypothesis and predict that poor quality of relictual wetlands in developed landscapes contributes to the absence of wood frogs ( Rana sylvatica = Lithobates sylvaticus) by decreasing their performance. Methods: In a translocation experiment, we reared wood frog larvae within enclosures in seven ponds where they naturally occur and in five ponds in developed landscapes where they are absent. Premature pond drying precluded assessing performance in one present pond and one absent pond. Results: Absent ponds were surrounded by upland buffers dominated by developed land covers while ponds with wood frog breeding populations were surrounded primarily by intact forest. Ponds were largely similar in their attributes. Survival and growth rate did not differ between pond types. Development tended to be slightly more rapid in some absent ponds perhaps related to higher water temperatures. Conclusions: Despite the highly altered landscapes surrounding them, we find no evidence that absent wetlands provide inferior habitat for wood frog larval recruitment. Performance in absent ponds matched or exceeded that observed in present ponds implying that absence of this species may stem from influences mediated by the upland landscape. These results provide a caution to the typically unexamined presumption that relictual habitats in developed landscapes are degraded in their utility for wildlife. [ABSTRACT FROM AUTHOR]

Aim It has been found that species richness can be a peaked function of natural area, meaning that conversion of natural cover can increase species numbers. Here, we test whether regional richness-environment relationships can predict local change in species richness. Location The greater park ecosystem of Thousand Islands National Park ( TINP ecosystem), Ontario, Canada. Methods We evaluated change in bird richness in 85 100-km2 sites, censused from 1981 to 1985 and from 2001 to 2005. We related change in richness over 20 years to change in natural land cover for sites having initially less or greater than half natural area to determine whether richness changes in the direction predicted. We also assessed the extent to which local effects (site-level extinction and colonization based on species-specific habitat amount and neighbourhood occupancy by conspecifics) affected the predictability of species richness response to environmental change. Results Local effects predicted bird richness changes through time far better than natural area change (adjusted r2 = 0.56 vs. adjusted r2 = 0.13). Species richness did not consistently respond to change in natural area in the directions predicted by the broader spatial richness-environment relationship, tending to increase with decrease in natural area regardless of the initial amount of natural area. The observed natural area changes (+0.7 km2 to −4.4 km2) were small relative to the changes in richness (+60 species to −37 species), likely impacting our ability to detect a response. Main conclusions The importance of local effects observed here in determining site-level species presence and consequently species richness has implications for species monitoring and the use of species richness as a measure of the avian response to land cover modification in Ontario. Detecting richness responses to environmental changes may often be challenged by low 'signal-to-noise' ratios and highlights the benefits of long-term species monitoring. [ABSTRACT FROM AUTHOR]

Large Eddy Simulations (LES) with the Conditional Moment Closure (CMC) combustion model of swirling ethanol spray flames have been performed in conditions close to blow-off for which a wide database of experimental measurements is available for both flame and spray characterization. The solution of CMC equations exploits a three-dimensional unstructured code with a first order closure for chemical source terms. It is shown that LES/CMC is able to properly capture the flame structure at different conditions and agrees reasonably well with the measurements both in terms of mean flame shape and dynamic behaviour of the flame evaluated in terms of local extinctions and statistics of the lift-off height. Experimental measurements of the overall (liquid plus gaseous) mixture fraction, performed using the Laser-Induced Breakdown Spectroscopy technique, are also included allowing further assessment and validation of the numerical method. The sensitivity of the simulation results to the various boundary conditions is discussed. [ABSTRACT FROM AUTHOR]