976 resultados para Resource-conservation
Resumo:
An assessment of marine elapid snakes found 9% of marine elapids are threatened with extinction, and an additional 6% are Near Threatened. A large portion (34%) is Data Deficient. An analysis of distributions revealed the greatest species diversity is found in Southeast Asia and northern Australia. Three of the seven threatened species occur at Ashmore and Hibernia Reefs in the Timor Sea, while the remaining threatened taxa occur in the Philippines, Niue, and Solomon Islands. The majority of Data Deficient species are found in Southeast Asia. Threats to marine snakes include loss of coral reefs and coastal habitat, incidental bycatch in fisheries, as well as fisheries that target snakes for leather. The presence of two Critically Endangered and one Endangered species in the Timor Sea suggests the area is of particular conservation concern. More rigorous, long-term monitoring of populations is needed to evaluate the success of "conservation measures" for marine snake species, provide scientifically based guidance for determining harvest quotas, and to assess the populations of many Data Deficient species.
Resumo:
Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed in order to highlight urgent conservation cases and inform environmental policy with appropriate biodiversity information in a timely manner. We present the first ever global analysis of extinction risk in reptiles, based on a random representative sample of 1500 species (16% of all currently known species). To our knowledge, our results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles. Nearly one in five reptilian species are threatened with extinction, with another one in five species classed as Data Deficient. The proportion of threatened reptile species is highest in freshwater environments, tropical regions and on oceanic islands, while data deficiency was highest in tropical areas, such as Central Africa and Southeast Asia, and among fossorial reptiles. Our results emphasise the need for research attention to be focussed on tropical areas which are experiencing the most dramatic rates of habitat loss, on fossorial reptiles for which there is a chronic lack of data, and on certain taxa such as snakes for which extinction risk may currently be underestimated due to lack of population information. Conservation actions specifically need to mitigate the effects of human-induced habitat loss and harvesting, which are the predominant threats to reptiles.
Resumo:
Buffer zones are vegetated strip-edges of agricultural fields along watercourses. As linear habitats in agricultural ecosystems, buffer strips dominate and play a leading ecological role in many areas. This thesis focuses on the plant species diversity of the buffer zones in a Finnish agricultural landscape. The main objective of the present study is to identify the determinants of floral species diversity in arable buffer zones from local to regional levels. This study was conducted in a watershed area of a farmland landscape of southern Finland. The study area, Lepsämänjoki, is situated in the Nurmijärvi commune 30 km to the north of Helsinki, Finland. The biotope mosaics were mapped in GIS. A total of 59 buffer zones were surveyed, of which 29 buffer strips surveyed were also sampled by plot. Firstly, two diversity components (species richness and evenness) were investigated to determine whether the relationship between the two is equal and predictable. I found no correlation between species richness and evenness. The relationship between richness and evenness is unpredictable in a small-scale human-shaped ecosystem. Ordination and correlation analyses show that richness and evenness may result from different ecological processes, and thus should be considered separately. Species richness correlated negatively with phosphorus content, and species evenness correlated negatively with the ratio of organic carbon to total nitrogen in soil. The lack of a consistent pattern in the relationship between these two components may be due to site-specific variation in resource utilization by plant species. Within-habitat configuration (width, length, and area) were investigated to determine which is more effective for predicting species richness. More species per unit area increment could be obtained from widening the buffer strip than from lengthening it. The width of the strips is an effective determinant of plant species richness. The increase in species diversity with an increase in the width of buffer strips may be due to cross-sectional habitat gradients within the linear patches. This result can serve as a reference for policy makers, and has application value in agricultural management. In the framework of metacommunity theory, I found that both mass effect(connectivity) and species sorting (resource heterogeneity) were likely to explain species composition and diversity on a local and regional scale. The local and regional processes were interactively dominated by the degree to which dispersal perturbs local communities. In the lowly and intermediately connected regions, species sorting was of primary importance to explain species diversity, while the mass effect surpassed species sorting in the highly connected region. Increasing connectivity in communities containing high habitat heterogeneity can lead to the homogenization of local communities, and consequently, to lower regional diversity, while local species richness was unrelated to the habitat connectivity. Of all species found, Anthriscus sylvestris, Phalaris arundinacea, and Phleum pretense significantly responded to connectivity, and showed high abundance in the highly connected region. We suggest that these species may play a role in switching the force from local resources to regional connectivity shaping the community structure. On the landscape context level, the different responses of local species richness and evenness to landscape context were investigated. Seven landscape structural parameters served to indicate landscape context on five scales. On all scales but the smallest scales, the Shannon-Wiener diversity of land covers (H') correlated positively with the local richness. The factor (H') showed the highest correlation coefficients in species richness on the second largest scale. The edge density of arable field was the only predictor that correlated with species evenness on all scales, which showed the highest predictive power on the second smallest scale. The different predictive power of the factors on different scales showed a scaledependent relationship between the landscape context and local plant species diversity, and indicated that different ecological processes determine species richness and evenness. The local richness of species depends on a regional process on large scales, which may relate to the regional species pool, while species evenness depends on a fine- or coarse-grained farming system, which may relate to the patch quality of the habitats of field edges near the buffer strips. My results suggested some guidelines of species diversity conservation in the agricultural ecosystem. To maintain a high level of species diversity in the strips, a high level of phosphorus in strip soil should be avoided. Widening the strips is the most effective mean to improve species richness. Habitat connectivity is not always favorable to species diversity because increasing connectivity in communities containing high habitat heterogeneity can lead to the homogenization of local communities (beta diversity) and, consequently, to lower regional diversity. Overall, a synthesis of local and regional factors emerged as the model that best explain variations in plant species diversity. The studies also suggest that the effects of determinants on species diversity have a complex relationship with scale.
Resumo:
The peptide hormone ghrelin is a potent orexigen produced predominantly in the stomach. It has a number of other biological actions, including roles in appetite stimulation, energy balance, the stimulation of growth hormone release and the regulation of cell proliferation. Recently, several ghrelin gene splice variants have been described. Here, we attempted to identify conserved alternative splicing of the ghrelin gene by cross-species sequence comparisons. We identified a novel human exon 2-deleted variant and provide preliminary evidence that this splice variant and in1-ghrelin encode a C-terminally truncated form of the ghrelin peptide, termed minighrelin. These variants are expressed in humans and mice, demonstrating conservation of alternative splicing spanning 90 million years. Minighrelin appears to have similar actions to full-length ghrelin, as treatment with exogenous minighrelin peptide stimulates appetite and feeding in mice. Forced expression of the exon 2-deleted preproghrelin variant mirrors the effect of the canonical preproghrelin, stimulating cell proliferation and migration in the PC3 prostate cancer cell line. This is the first study to characterise an exon 2-deleted preproghrelin variant and to demonstrate sequence conservation of ghrelin gene-derived splice variants that encode a truncated ghrelin peptide. This adds further impetus for studies into the alternative splicing of the ghrelin gene and the function of novel ghrelin peptides in vertebrates.
Resumo:
Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is a common stored grain pest for which a wide range of suitable resources has been recorded. These beetles are facultatively fungivorous and their resource range may extend to fungi associated with non-grain resources (e.g. cotton seed) and other decaying plant matter. Little is known with respect to fungi in terms of resource location by these beetles in the field. We, therefore, conducted a series of experiments in laboratory arenas, glasshouse cages and the field to determine how beetles respond to grain resources in relation to cotton seed (together with its lint stubble and associated fungal flora). Results from the tests conducted in relatively small arenas and cages in the laboratory and glasshouse reveal that the responses of T. castaneum adults to food resources were twice as strong when walking as when flying (as measured by the proportion of the released beetles that were trapped). Also, a clear preference for linted cotton seeds was evident in walking T. castaneum, especially in small-scale arenas in the laboratory, where at least 60% of beetles released preferred linted cotton seeds over wheat and sorghum. Similarly, in cages (1 m3) they responded five times more strongly to linted cotton seed than to conventional grain resources. However, this pattern was not consistent with those obtained from field trapping over 20 m and the beetles did not show any particular preference to any of the resources tested above. Our results suggest a focus on walking beetles in trapping studies for population estimations and, for developing effective food-based trapping lures, the potential use of active volatiles from the fungi associated with linted cotton seed. © 2012 Elsevier Ltd.
Resumo:
Arguing the value of effective HRM practice has long been a focus in the HRM literature. However, there is also a case for identifying the risks presented by inappropriate or absent HRM practices. Although risk management has been established in the broader management literature for over two decades, human resource related risks have not featured as prominently as other types of risks. HRM as a discipline has a role to play in addressing this situation and raising awareness of human resource issues as risks for the organization. A review of papers published since the year 2000 in a broad range of high quality management journals, identifies that limited research has thus far taken a risk management perspective on human resources. Although the HRM and risk management disciplines stand to benefit from drawing the two areas together, this review concludes that further research and development of the phenomenon of human resource risk management is needed.
Resumo:
The large size, high trophic level and wide distribution of Hexanchiformes (cow and frilled sharks) should position this order as important apex predators in coastal and deep-water ecosystems. This review synthesizes available information on Hexanchiformes, including information not yet published, with the purpose of evaluating their conservation status and assessing their ecological roles in the dynamics of marine ecosystems. Comprising six species, this group has a wide global distribution, with members occurring from shallow coastal areas to depths of c. 2500 m. The limited information available on their reproductive biology suggests that they could be vulnerable to overexploitation (e.g. small litter sizes for most species and suspected long gestation periods). Most of the fishing pressure exerted on Hexanchiformes is in the form of commercial by-catch or recreational fishing. Comprehensive stock and impact assessments are unavailable for most species in most regions due to limited information on life history and catch and abundance time series. When hexanchiform species have been commercially harvested, however, they have been unable to sustain targeted fisheries for long periods. The potentially high vulnerability to intense fishing pressure warrants a conservative exploitation of this order until thorough quantitative assessments are conducted. At least some species have been shown to be significant apex predators in the systems they inhabit. Should Hexanchiformes be removed from coastal and deep-water systems, the lack of sympatric shark species that share the same resources suggests no other species would be capable of fulfilling their apex predator role in the short term. This has potential ecosystem consequences such as meso-predator release or trophic cascades. This review proposes some hypotheses on the ecology of Hexanchiformes and their role in ecosystem dynamics, highlighting the areas where critical information is required to stimulate research directions.
Resumo:
The Rhipicephalus micro plus genome is large and complex in structure, making it difficult to assemble a genome sequence and costly to resource the required bioinformatics. In light of this, a consortium of international collaborators was formed to pool resources to begin sequencing this genome. We have acquired and assembled genomic DNA into contigs that represent over 1.8 Gigabase pairs of DNA from gene-enriched regions of the R. micro plus genome. We also have several datasets containing transcript sequences from a number of gene expression experiments conducted by the consortium. A web-based resource was developed to enable the scientific community to access our datasets and conduct analysis through a web-based bioinformatics environment called YABI. The collective bioinformatics resource is termed CattleTickBase. Our consortium has acquired genomic and transcriptomic sequence data at approximately 0.9X coverage of the gene-coding regions of the R. microplus genome. The YABI tool will facilitate access and manipulation of cattle tick genome sequence data as the genome sequencing of R. microplus proceeds. During this process the CattleTickBase resource will continue to be updated. Published by Elsevier Ltd. on behalf of Australian Society for Parasitology Inc.
Resumo:
This study investigated within-person relationships between daily problem solving demands, selection, optimization, and compensation (SOC) strategy use, job satisfaction, and fatigue at work. Based on conservation of resources theory, it was hypothesized that high SOC strategy use boosts the positive relationship between problem solving demands and job satisfaction, and buffers the positive relationship between problem solving demands and fatigue. Using a daily diary study design, data were collected from 64 administrative employees who completed a general questionnaire and two daily online questionnaires over four work days. Multilevel analyses showed that problem solving demands were positively related to fatigue, but unrelated to job satisfaction. SOC strategy use was positively related to job satisfaction, but unrelated to fatigue. A buffering effect of high SOC strategy use on the demands-fatigue relationship was found, but no booster effect on the demands-satisfaction relationship. The results suggest that high SOC strategy use is a resource that protects employees from the negative effects of high problem solving demands.
Resumo:
The Mobulidae are zooplanktivorous elasmobranchs comprising two recognized species of manta rays (Manta spp.) and nine recognized species of devil rays (Mobula spp.). They are found circumglobally in tropical, subtropical and temperate coastal waters. Although mobulids have been recorded for over 400 years, critical knowledge gaps still compromise the ability to assess the status of these species. On the basis of a review of 263 publications, a comparative synthesis of the biology and ecology of mobulids was conducted to examine their evolution, taxonomy, distribution, population trends, movements and aggregation, reproduction, growth and longevity, feeding, natural mortality and direct and indirect anthropogenic threats. There has been a marked increase in the number of published studies on mobulids since c. 1990, particularly for the genus Manta, although the genus Mobula remains poorly understood. Mobulid species have many common biological characteristics although their ecologies appear to be species-specific, and sometimes region-specific. Movement studies suggest that mobulids are highly mobile and have the potential to rapidly travel large distances. Fishing pressure is the major threat to many mobulid populations, with current levels of exploitation in target fisheries unlikely to be sustainable. Advances in the fields of population genetics, acoustic and satellite tracking, and stable-isotope and fatty-acid analyses will provide new insights into the biology and ecology of these species. Future research should focus on the uncertain taxonomy of mobulid species, the degree of overlap between their large-scale movement and human activities such as fisheries and pollution, and the need for management of inter-jurisdictional fisheries in developing nations to ensure their long-term sustainability. Closer collaboration among researchers worldwide is necessary to ensure standardized sampling and modelling methodologies to underpin global population estimates and status.
Resumo:
Since the first investigation 25 years ago, the application of genetic tools to address ecological and evolutionary questions in elasmobranch studies has greatly expanded. Major developments in genetic theory as well as in the availability, cost effectiveness and resolution of genetic markers were instrumental for particularly rapid progress over the last 10 years. Genetic studies of elasmobranchs are of direct importance and have application to fisheries management and conservation issues such as the definition of management units and identification of species from fins. In the future, increased application of the most recent and emerging technologies will enable accelerated genetic data production and the development of new markers at reduced costs, paving the way for a paradigm shift from gene to genome-scale research, and more focus on adaptive rather than just neutral variation. Current literature is reviewed in six fields of elasmobranch molecular genetics relevant to fisheries and conservation management (species identification, phylogeography, philopatry, genetic effective population size, molecular evolutionary rate and emerging methods). Where possible, examples from the Indo-Pacific region, which has been underrepresented in previous reviews, are emphasized within a global perspective. (C) 2012 The Authors Journal of Fish Biology (C) 2012 The Fisheries Society of the British Isles
Resumo:
High levels of hydrological connectivity during seasonal flooding provide significant opportunities for movements of fish between rivers and their floodplains, estuaries and the sea, possibly mediating food web subsidies among habitats. To determine the degree of utilisation of food sources from different habitats in a tropical river with a short floodplain inundation duration (similar to 2 months), stable isotope ratios in fishes and their available food were measured from three habitats (inundated floodplain, dry season freshwater, coastal marine) in the lower reaches of the Mitchell River, Queensland (Australia). Floodplain food sources constituted the majority of the diet of large-bodied fishes (barramundi Lates calcarifer, catfish Neoarius graeffei) captured on the floodplain in the wet season and for gonadal tissues of a common herbivorous fish (gizzard shad Nematalosa come), the latter suggesting that critical reproductive phases are fuelled by floodplain production. Floodplain food sources also subsidised barramundi from the recreational fishery in adjacent coastal and estuarine areas, and the broader fish community from a freshwater lagoon. These findings highlight the importance of the floodplain in supporting the production of large fishes in spite of the episodic nature and relatively short duration of inundation compared to large river floodplains of humid tropical regions. They also illustrate the high degree of food web connectivity mediated by mobile fish in this system in the absence of human modification, and point to the potential consequences of water resource development that may reduce or eliminate hydrological connectivity between the river and its floodplain.
Resumo:
Köyhiä maanviljelijöitä on usein syytetty kehitysmaiden ympäristöongelmista. On väitetty, että eloonjäämistaistelu pakottaa heidät käyttämään maata ja muita luonnonvaroja lyhytnäköisesti. Harva asiaa koskeva tutkimus on kuitenkaan tukenut tätä väitettä; perheiden köyhyyden astetta ja heidän aiheuttamaansa ympäristövaikutusta ei ole kyetty kytkemään toisiinsa. Selkeyttääkseen köyhyys-ympäristö –keskustelua, Thomas Reardon ja Steven Vosti kehittivät investointiköyhyyden käsitteen. Se tunnistaa sen kenties suuren joukon maanviljelijäperheitä, jotka eivät ole köyhiä perinteisten köyhyysmittareiden mukaan, mutta joiden hyvinvointi ei ole riittävästi köyhyysrajojen yläpuolella salliakseen perheen investoida kestävämpään maankäyttöön. Reardon ja Vosti korostivat myös omaisuuden vaikutusta perheiden hyvinvointiin, ja uskoivat sen vaikuttavan tuotanto- ja investointipäätöksiin. Tässä tutkimuksessa pyritään vastaamaan kahteen kysymykseen: Miten investointiköyhyyttä voidaan ymmärtää ja mitata? Ja, mikä on viljelijäperheiden omaisuuden hyvinvointia lisäävä vaikutus? Tätä tutkimusta varten haastateltiin 402 maanviljelijäperhettä Väli-Amerikassa, Panaman tasavallan Herreran läänissä. Näiden perheiden hyvinvointia mitattiin heidän kulutuksensa mukaan, ja paikalliset köyhyysrajat laskettiin paikallisen ruoan hinnan mukaan. Herrerassa ihminen tarvitsee keskimäärin 494 dollaria vuodessa saadakseen riittävän ravinnon, tai 876 dollaria vuodessa voidakseen ravinnon lisäksi kattaa muitakin välttämättömiä menoja. Ruoka- eli äärimmäisen köyhyyden rajan alle jäi 15,4% tutkituista perheistä, ja 33,6% oli jokseenkin köyhiä, eli saavutti kyllä riittävän ravitsemuksen, muttei kyennyt kustantamaan muita perustarpeitaan. Molempien köyhyysrajojen yläpuolelle ylsi siis 51% tutkituista perheistä. Näiden köyhyysryhmien välillä on merkittäviä eroavaisuuksia ei vain perheiden varallisuuden, tulojen ja investointistrategioiden välillä, mutta myös perheiden rakenteessa, elinympäristössä ja mahdollisuuksissa saada palveluja. Investointiköyhyyden mittaaminen osoittautui haastavaksi. Herrerassa viljelijät eivät tee investointeja puhtaasti ympäristönsuojeluun, eikä maankäytön kestävyyttä muutenkaan pystytty yhdistämään perheiden hyvinvoinnin tasoon. Siksi investointiköyhyyttä etsittiin sellaisena hyvinvoinnin tasona, jonka alapuolella elävien perheiden parissa tuottavat maanparannusinvestoinnit eivät enää ole suorassa suhteessa hyvinvointiin. Tällaisia investointeja ovat mm. istutetut aidat, lannoitus ja paranneltujen laiduntyyppien viljely. Havaittiin, että jos perheen hyvinvointi putoaa alle 1000 dollarin/henkilö/vuosi, tällaiset tuottavat maanparannusinvestoinnit muuttuvat erittäin harvinaisiksi. Investointiköyhyyden raja on siis noin kaksi kertaa riittävän ravitsemuksen hinta, ja sen ylitti 42,3% tutkituista perheistä. Heille on tyypillistä, että molemmat puolisot käyvät työssä, ovat korkeasti koulutettuja ja yhteisössään aktiivisia, maatila tuottaa paremmin, tilalla kasvatetaan vaativampia kasveja, ja että he ovat kerryttäneet enemmän omaisuutta kuin investointi-köyhyyden rajan alla elävät perheet. Tässä tutkimuksessa kyseenalaistettiin yleinen oletus, että omaisuudesta olisi poikkeuksetta hyötyä viljelijäperheelle. Niinpä omaisuuden vaikutusta perheiden hyvinvointiin tutkittiin selvittämällä, mitä reittejä pitkin perheiden omistama maa, karja, koulutus ja työikäiset perheenjäsenet voisivat lisätä perheen hyvinvointia. Näiden hyvinvointi-mekanismien ajateltiin myös riippuvan monista väliin tulevista tekijöistä. Esimerkiksi koulutus voisi lisätä hyvinvointia, jos sen avulla saataisiin paremmin palkattuja töitä tai perustettaisiin yritys; mutta näihin mekanismeihin saattaa vaikuttaa vaikkapa etäisyys kaupungeista tai se, omistaako perhe ajoneuvon. Köyhimpien perheiden parissa nimenomaan koulutus olikin ainoa tutkittu omaisuuden muoto, joka edisti perheen hyvinvointia, kun taas maasta, karjasta tai työvoimasta ei ollut apua köyhyydestä nousemiseen. Varakkaampien perheiden parissa sen sijaan korkeampaa hyvinvointia tuottivat koulutuksen lisäksi myös maa ja työvoima, joskin monesta väliin tulevasta muuttujasta, kuten tuotantopanoksista riippuen. Ei siis ole automaatiota, jolla omaisuus parantaisi perheiden hyvinvointia. Vaikka rikkailla onkin yleensä enemmän karjaa kuin köyhemmillä, ei tässä aineistossa löydetty yhtään mekanismia, jota kautta karjan määrä tuottaisi korkeampaa hyvinvointia viljelijäperheille. Omaisuuden keräämisen ja hyödyntämisen strategiat myös muuttuvat hyvinvoinnin kasvaessa ja niihin vaikuttavat monet ulkoiset tekijät. Ympäristön ja köyhyyden suhde on siis edelleen epäselvä. Köyhyyden voittaminen vaatii pitkällä tähtäimellä sitä, että viljelijäperheet nousisivat investointiköyhyyden rajan yläpuolelle. Näin heillä olisi varaa alkaa kartuttaa omaisuutta ja investoida kestävämpään maankäyttöön. Tällä hetkellä kuitenkin isolle osalle herreralaisia perheitä tuo raja on kaukana tavoittamattomissa. Miten päästä yli tuhannen dollarin kulutukseen perheenjäsentä kohden, mikäli elintaso ei yllä edes riittävään ravitsemukseen? Ja sittenkin, vaikka hyvinvointi kohenisi, ei ympäristön kannalta parannuksia ole välttämättä odotettavissa, mikäli karjalaumat kasvavat ja eroosioalttiit laitumet leviävät.