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The evolution of male breeding aggregations is difficult to explain because males may reduce their reproductive success by
associating with their closest competitors. We examined aggregative behavior by male New Mexico spadefoot toads, Spea multiplicata, which form breeding choruses in rain-filled pools. We specifically asked whether males are attracted to conspecific calls
and, if so, whether they preferentially associate with those male calls that are also attractive to females. Field observations
revealed that males showed significant clustering with conspecifics within breeding ponds, whereas laboratory phonotaxis experiments
revealed that males preferentially associated with conspecific male calls. Moreover, when males were presented with conspecific
calls that differed in call rate, smaller males associated with the stimulus preferred by females (average call rate). Thus,
males appear to evaluate the attractiveness of competitors using the same trait employed by females to assess potential mates,
and males adjust their positions relative to competitors depending on their size. We discuss these results in the light of
several current hypotheses on the adaptive significance of male breeding aggregations.
Received: 20 December 1999 / Accepted: 18 March 2000 相似文献
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Assessing and Prioritizing Ecological Communities for Monitoring in a Regional Habitat Conservation Plan 总被引:1,自引:1,他引:0
In nature reserves and habitat conservation areas, monitoring is required to determine if reserves are meeting their goals for preserving species, ecological communities, and ecosystems. Increasingly, reserves are established to protect multiple species and communities, each with their own conservation goals and objectives. As resources are always inadequate to monitor all components, criteria must be applied to prioritize both species and communities for monitoring and management. While methods for prioritizing species based on endangerment or risk have been established, approaches to prioritizing ecological communities for monitoring are not well developed, despite a long-standing emphasis on communities as target elements in reserve design. We established guidelines based on four criteria derived from basic principles of conservation and landscape ecology--extent, representativeness, fragmentation, and endangerment--to prioritize communities in the San Diego Multiple Species Conservation Plan (MSCP). The MSCP was one of the first multiple-species habitat conservation areas established in California, USA, and it has a complex spatial configuration because of the patterns of surrounding land use, which are largely urbanized. In this case study, high priority communities for monitoring include coastal sage scrub (high endangerment, underrepresented within the reserve relative to the region, and moderately fragmented), freshwater wetlands, and coastal habitats (both have high fragmentation, moderate endangerment and representativeness, and low areal extent). This framework may be useful to other conservation planners and land managers for prioritizing the most significant and at-risk communities for monitoring. 相似文献
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Effects of uncertainty and variability on population declines and IUCN Red List classifications 下载免费PDF全文
Pamela Rueda‐Cediel Kurt E. Anderson Tracey J. Regan Helen M. Regan 《Conservation biology》2018,32(4):916-925
The International Union for Conservation of Nature (IUCN) Red List Categories and Criteria is a quantitative framework for classifying species according to extinction risk. Population models may be used to estimate extinction risk or population declines. Uncertainty and variability arise in threat classifications through measurement and process error in empirical data and uncertainty in the models used to estimate extinction risk and population declines. Furthermore, species traits are known to affect extinction risk. We investigated the effects of measurement and process error, model type, population growth rate, and age at first reproduction on the reliability of risk classifications based on projected population declines on IUCN Red List classifications. We used an age‐structured population model to simulate true population trajectories with different growth rates, reproductive ages and levels of variation, and subjected them to measurement error. We evaluated the ability of scalar and matrix models parameterized with these simulated time series to accurately capture the IUCN Red List classification generated with true population declines. Under all levels of measurement error tested and low process error, classifications were reasonably accurate; scalar and matrix models yielded roughly the same rate of misclassifications, but the distribution of errors differed; matrix models led to greater overestimation of extinction risk than underestimations; process error tended to contribute to misclassifications to a greater extent than measurement error; and more misclassifications occurred for fast, rather than slow, life histories. These results indicate that classifications of highly threatened taxa (i.e., taxa with low growth rates) under criterion A are more likely to be reliable than for less threatened taxa when assessed with population models. Greater scrutiny needs to be placed on data used to parameterize population models for species with high growth rates, particularly when available evidence indicates a potential transition to higher risk categories. 相似文献
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Environmental management decisions typically lie at the interface of science and public policy. Consequently, these decisions involve a number of stakeholders with competing agendas and vested interests in the ultimate decision. In such cases, it is appropriate to adopt formal methods for consensus building to ensure transparent and repeatable decisions. In this paper, we use an environmental management case study to demonstrate the utility of a mathematical consensus convergence model in aggregating values (or weights) across groups. Consensus models are applicable when all parties agree to negotiate in order to resolve conflict. The advantage of this method is that it does not require that all members of the group reach agreement, often an impossible task in group decision making. Instead, it uses philosophical foundations in consensus building to aggregate group members' values in a way that guarantees convergence towards a single consensual value that summarizes the group position. We highlight current problems with ad hoc consensus and negotiation methods, provide justification for the adoption of formal consensus convergence models and compare the consensus convergence model with currently used methods for aggregating values across a group in a decision making context. The model provides a simple and transparent decision support tool for group decision making that is straightforward to implement. 相似文献
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Suzanne M. O’Regan Denis FlynnThomas C. Kelly Michael J.A. O’CallaghanAlexei V. Pokrovskii Dmitrii Rachinskii 《Ecological modelling》2012,224(1):54-64
The recent rapid growth of the woodpigeon population in the British Isles is a cause for concern for environmental managers. It is unclear what has driven their increase in abundance. Using a mathematical model, we explored two possible mechanisms, reduced intraspecific competition for food and increased reproductive success. We developed an age-structured hybrid model consisting of a system of ordinary differential equations that describes density-dependent mortality and a discrete component, which represents the birth-pulse. We investigated equilibrium population dynamics using our model. The two hypotheses predict contrasting population age profiles at equilibrium. We adapted the model to examine the impacts of control measures. We showed that an annual shooting season that follows the period of density-dependent mortality is the most effective control strategy because it simultaneously removes adult and juvenile woodpigeons. The model is a first step towards understanding the processes that influence the dynamics of woodpigeon populations. 相似文献
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Ciprian Briciu-Burghina Timothy Sullivan James Chapman Fiona Regan 《Environmental monitoring and assessment》2014,186(9):5561-5580
High-frequency, continuous monitoring using in situ sensors offers a comprehensive and improved insight into the temporal and spatial variability of any water body. In this paper, we describe a 7-month exploratory monitoring programme in Dublin Port, demonstrating the value of high-frequency data in enhancing knowledge of processes, informing discrete sampling, and ultimately increasing the efficiency of port and environmental management. Kruskal–Wallis and Mann–Whitney tests were used to show that shipping operating in Dublin Port has a small–medium effect on turbidity readings collected by in situ sensors. Turbidity events are largely related to vessel activity in Dublin Port, caused by re-suspension of sediments by vessel propulsion systems. The magnitudes of such events are strongly related to water level and tidal state at vessel arrival times. Crucially, measurements of Escherichia coli and enterococci contamination from discrete samples taken at key periods related to detected turbidity events were up to nine times higher after vessel arrival than prior to disturbance. Daily in situ turbidity patterns revealed time-dependent water quality “hot spots” during a 24-h period. We demonstrate conclusively that if representative environmental assessment of water quality is to be performed at such sites, sampling times, informed by continous monitoring data, should take into account these daily variations. This work outlines the potential of sensor technologies and continuous monitoring, to act as a decision support tool in both environmental and port management. 相似文献
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Vincent Carragher Bernadette O’Regan Michael Peters Richard Moles 《Local Environment》2018,23(5):518-535
Climate change communication to the Public is in general presented in a negative fashion and often depicts the resultant costs and impacts as distant. Its substantial gloom together with the less immediate consequences significantly weaken responses. Narratives and stories are potent arbiters of meaningful communication and are an important vehicle for communication in our information-rich lives. Importantly, they reduce jargon, gather and translate information, provide insight, reframe evidence and engage audiences. It has been argued by many observers that stories are potentially useful in driving change; presenting a way to value what is gone, expressing emotions, and helping us assert our determination to salvage something and work towards the future. This paper details the methods utilised by the authors to generate stories and case studies in a community in Ireland over a 4-year research period. The aim of the work was to identify and assess the salience and potency of storytelling – as part of a “co-creation” process – with regard to galvanising local action in the generation of sustainable models of lifestyle practice for residents. In this paper, co-creation includes the planning phase of co-design and the implementation phase of co-production. The demonstration of these sustainable lifestyle practices was a strong driver for the sustainable transition of this community supporting the reduction of its ecological footprint by 28% over 4 years, evidence of which is highlighted in this paper. 相似文献
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Chen Chen Jessica Hellmann Lea Berrang-Ford Ian Noble Patrick Regan 《Mitigation and Adaptation Strategies for Global Change》2018,23(1):101-122
Equity and efficiency should be considered when allocating resources for climate change adaptation. More than a decade after the Least Developed Countries Fund approved adaptation funds for 18 countries in 2003, it is possible to take the stock of investment data and to test empirically whether equity and efficiency have been factored into adaptation investment decision-making. To evaluate equity, one must determine if resources were distributed to areas of greatest need. Vulnerability assessments provide information on the global distribution of the need for adaptation. To evaluate efficiency, one must compare cost and benefit of an investment. Although it is difficult to assess ex-ante the cost and benefit of investment strategies, it is possible to measure efficient use of expenditures with readiness assessment, as a metric of capacity to deploy adaptation resources. We used vulnerability and readiness measures of the Notre Dame Global Adaptation Initiative (ND-GAIN) Country Index as proxies of equity and efficiency. This article quantitatively interrogates—through the lens of public fund allocation—the roles of vulnerability and readiness in shaping adaptation investment decisions. Our findings suggest that countries facing increasing impacts from climate change have received more adaptation investments from international sources than countries with less vulnerability. Further, international investments also preferentially flow to countries that are more ready to deploy adaptation resources. Since the most vulnerable countries are likely to be less ready for investment, our findings support the efforts to improve the investment potential of the most vulnerable countries by investing first to enhance their readiness, in order to unlock adaptation solutions. 相似文献
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