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61.
We examined the influence of female feeding regime on polyandry in the nuptially feeding nursery web spider (Pisaura mirabilis). In this species, the nuptial gift, a dead prey item wrapped in the male’s silk, is physically separate from the ejaculate.
We manipulated female feeding regime (starved or fed) and the presence or absence of a gift with three successive males to
test direct-benefits hypotheses (nuptial gift or sperm supply) for the expression of polyandry. The presence of a gift was
necessary for copulation, as no male without a gift successfully copulated. Female mating behavior most strongly supports
polyandry due to the accumulation of gifted food items (“nuptial gift” direct-benefits hypothesis). Starved females that were
presented with a gift accepted significantly more gifts and inseminations than fed females. Most starved females (74%) copulated
two or more times, as opposed to only 3% of the fed females. Nearly all of the females that accepted a gift subsequently copulated.
The nuptial gift item seems to function as male mating effort and females appear to receive multiple matings as part of a
feeding strategy. 相似文献
62.
Nicolas P. Zegre Andrew J. Miller Aaron Maxwell Samuel J. Lamont 《Journal of the American Water Resources Association》2014,50(5):1257-1272
In the Appalachian region of the eastern United States, mountaintop removal mining (MTM) is a dominant driver of land‐cover change, impacting 6.8% of the largely forested 4.86 million ha coal fields region. Recent catastrophic flooding and documented biological impairment downstream of MTM has drawn sharp criticism to this practice. Despite its extent, scale, and use since the 1970s, the impact of MTM on hydrology is poorly understood. Therefore, the goal of this study was a multiscale evaluation to establish the nature of hydrologic impacts associated with MTM. To quantify the extent of MTM, land‐cover change over the lifetime of this practice is estimated for a mesoscale watershed in southern West Virginia. To assess hydrologic impacts, we conducted long‐term trend analyses to evaluate for systematic changes in hydrology at the mesoscale, and conducted hydrometric and response time modeling to characterize storm‐scale responses of a MTM‐impacted headwater catchment. Results show a general trend in the conversion of forests to mines, and significant decreases in maximum streamflow and variability, and increases in base‐flow ratio attributed to valley fills and deep mine drainage. Decreases in variability are shown across spatial and temporal scales having important implications for water quantity and quality. However, considerable research is necessary to understand how MTM impacts hydrology. In an effort to inform future research, we identify existing knowledge gaps and limitations of our study. 相似文献
63.
Natural and man-made emergencies are regular occurrences in the Greater Horn of Africa region. The underlying impoverishment of whole populations is increasing, making it more difficult to distinguish between humanitarian crises triggered by shocks and those resulting from chronic poverty. Shocks and hazards can no longer be seen as one-off events that trigger a one-time response. In countries that are both poor and exposed to frequent episodes of debilitating drought or chronic conflict, information needs tend to be different from the straightforward early warning/commodity accounting models of information systems that have proven reliable in past emergencies. This paper describes the interdependent components of a humanitarian information system appropriate for this kind of complex environment, noting the analytical links between the components and operational links to programme and policy. By examining a series of case studies from the Greater Horn region, the paper demonstrates that systems lacking one or more of these components will fail to provide adequate information--and thus incur humanitarian costs. While information always comes with a cost, the price of poor information--or none--is higher. And in situations of chronic vulnerability, in which development interventions are likely to be interspersed with both safety nets and emergency interventions on a recurrent basis, investment in improved information is a good investment from both a humanitarian and a financial viewpoint. 相似文献
64.
Katharina-Victoria Pérez-Hämmerle Katie Moon Rubén Venegas-Li Sean Maxwell Jeremy S. Simmonds Oscar Venter Stephen T. Garnett Hugh P. Possingham James E. M. Watson 《Conservation biology》2022,36(4):e13875
With the intention of securing industry-free land and seascapes, protecting wilderness entered international policy as a formal target for the first time in the zero draft of the Post-2020 Global Biodiversity Framework under the Convention on Biological Diversity. Given this increased prominence in international policy, it is timely to consider the extent to which the construct of wilderness supports global conservation objectives. We evaluated the construct by overlaying recently updated cumulative human pressure maps that offer a global-scale delineation of industry-free land as wilderness with maps of carbon stock, species richness, and ground travel time from urban centers. Wilderness areas took variable forms in relation to carbon stock, species richness, and proximity to urban centers, where 10% of wilderness areas represented high carbon and species richness, 20% low carbon and species richness, and 3% high levels of remoteness (>48 h), carbon, and species richness. Approximately 35% of all remaining wilderness in 2013 was accessible in <24 h of travel time from urban centers. Although the construct of wilderness can be used to secure benefits in specific contexts, its application in conservation must account for contextual and social implications. The diverse characterization of wilderness under a global environmental conservation lens shows that a nuanced framing and application of the construct is needed to improve understanding, communication, and retention of its variable forms as industry-free places. 相似文献
65.
Kongkuah Maxwell Yao Hongxing Yilanci Veli 《Environment, Development and Sustainability》2022,24(4):4684-4708
Environment, Development and Sustainability - The study tests the EKC hypothesis, forecasts future paths, and models the dynamic relationship between ecological and economic variables in China. The... 相似文献