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The Science of Nature - 相似文献
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Jennifer F. Lind‐Riehl Audrey L. Mayer Adam M. Wellstead Oliver Gailing 《Conservation biology》2016,30(6):1288-1296
The U.S. Endangered Species Act (ESA) requires that the “best available scientific and commercial data” be used to protect imperiled species from extinction and preserve biodiversity. However, it does not provide specific guidance on how to apply this mandate. Scientific data can be uncertain and controversial, particularly regarding species delineation and hybridization issues. The U.S. Fish and Wildlife Service (FWS) had an evolving hybrid policy to guide protection decisions for individuals of hybrid origin. Currently, this policy is in limbo because it resulted in several controversial conservation decisions in the past. Biologists from FWS must interpret and apply the best available science to their recommendations and likely use considerable discretion in making recommendations for what species to list, how to define those species, and how to recover them. We used semistructured interviews to collect data on FWS biologists’ use of discretion to make recommendations for listed species with hybridization issues. These biologists had a large amount of discretion to determine the best available science and how to interpret it but generally deferred to the scientific consensus on the taxonomic status of an organism. Respondents viewed hybridization primarily as a problem in the context of the ESA, although biologists who had experience with hybridization issues were more likely to describe it in more nuanced terms. Many interviewees expressed a desire to continue the current case‐by‐case approach for handling hybridization issues, but some wanted more guidance on procedures (i.e., a “flexible” hybrid policy). Field‐level information can provide critical insight into which policies are working (or not working) and why. The FWS biologists’ we interviewed had a high level of discretion, which greatly influenced ESA implementation, particularly in the context of hybridization. 相似文献
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Jiří Kopáček Jan Turek Josef Hejzlar Hana Šantrůčková 《Atmospheric environment (Oxford, England : 1994)》2009,43(34):5443-5453
Precipitation and throughfall fluxes of major ions, nutrients (C, N, P), and metals (Al, Fe, Mn), and the chemical composition of litter fall and living plant tissue in Norway spruce stands (the Bohemian Forest; Czech Republic), were used to evaluate how microbial processes and decay of plant tissue in canopies influence canopy leaching (CL) of elements. Proton exchange for Mg2+, Ca2+, and K+ in decaying biomass and co-transport of Ca2+ and K+ out of plant cells with organic acid anions were the most likely processes contributing to CL of base cations. The CL of total P and N (and also NO3?) was minor. Important proportions of the N and P mineral forms were transformed to organic forms by microbial processes (primary and bacterial production), with the respective CL of ?13.9 and 16.4 mmol m?2 yr?1 for NH4+ and organic N, and ?0.33 and 0.22 mmol m?2 yr?1 for dissolved reactive P (DRP) and organic P. Most of particulate P and N in throughfall (~90%) originated from microbial DRP and NH4+ transformations, but particulate C mostly came from the fragmentation of plant tissue (58%). Among metals, CL was not observed for Al, was small for Fe (0.3 mmol m?2 yr?1), and greatest for Mn (0.9 mmol m?2 yr?1) due to leaching from decaying tissue by acidic precipitation. 相似文献
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Hana Patzenhauerová Josef Bryja Radim Šumbera 《Behavioral ecology and sociobiology》2010,64(5):757-767
The African mole-rats (Bathyergidae, Rodentia) are subterranean rodents that have evolved a wide range of social organisations
varying from solitary to eusocial. Due to some unusual features of their breeding and social systems, much attention has been
focused on social species, with solitary species being virtually ignored. Here, we present the first genetic study on the
mating system of any solitary mole-rats, the silvery mole-rat (Heliophobius argenteocinereus) - a species which is assumed to be monogamous. Microsatellite markers were used to analyse the mating system and the kinship
structure in populations in southern Malawi. Isolation by distance between individuals was apparent in two studied populations,
but not in the third, probably, as a result of barriers limiting dispersal in the latter population. Polygyny was found to
be a mating system in this population, where a strongly female-biased adult sex ratio was present. In this case, large distances
between the burrow systems of mating partners exclude the possibility of belowground searching for mates, suggesting that
the males might seek females aboveground. Interestingly, among analysed litters from various localities, one multiple-sired
litter was found. Therefore, the results suggest that the mating system in potentially monogamous solitary subterranean rodents
may be much more variable than expected and can differ among populations. 相似文献