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51.
Ruchira Sen Heather D. Ishak Trevor R. Kniffin Ulrich G. Mueller 《Behavioral ecology and sociobiology》2010,64(7):1125-1133
Interspecies or intraspecies cooperation can be stabilized evolutionarily if choosing partners favor beneficial partners and
discriminate against non-beneficial partners. We quantified such partner choice (symbiont choice) in the leafcutter ant Atta texana (Attini, Formicidae) by presenting the ants in a cafeteria-style preference assay with genotypically distinct fungal cultivars
from A. texana and Acromyrmex versicolor. Symbiont choice was measured as the ants' tendency to choose one or more cultivar(s) from several pure (axenic) cultivar
fragments and convert a given fungal fragment into a garden. Microsatellite DNA fingerprinting enabled us to identify the
cultivars chosen by the ants for their gardens. In 91% of the choice tests, A. texana workers combined multiple cultivars into a single intercropped, chimaeric garden, and the cultivars coexisted in such chimaeric
gardens for as long as 4 months. Coexistence of distinct fungal genotypes in chimaeric gardens appears to contradict a recent
model of cultivar competition postulating that each cultivar secretes incompatibility compounds harming other cultivars, which
presumably would preclude the intercropped polyculture observed in our experiments. Although we found no clear evidence of
novel, recombinant genotypes in the experimental chimaeric gardens, the intercropping of cultivar genotypes may occasionally
lead under natural conditions to exchange of genetic material between coexisting cultivars, thus introducing novel cultivar
genotypes into the leafcutter symbiosis. Symbiont choice by ants and any competition between coexisting cultivar strains in
chimaeric gardens do not appear to operate fast enough in our laboratory assay to convert chimaeric gardens into the monocultures
observed for A. texana under natural conditions. 相似文献
52.
Jonathan D. Choquette Jacqueline D. Litzgus Joanne X. Y. Gui Trevor E. Pitcher 《Conservation biology》2023,37(1):e14016
Advancements in the field of reintroduction biology are needed, but understanding of how to effectively conduct translocations, particularly with snakes, is lacking. We conducted a systematic review of snake translocation studies to identify potential tactics for reducing postrelease effects. We included studies on intentional, human-mediated, wild–wild, or captive–wild translocations to any location, regardless of motive or number of snakes translocated. Only studies that presented results for at least 1 of 4 outcomes (movement behavior, site fidelity, survival, or population establishment) were included. We systematically searched 4 databases for published studies and used 5 methods to search the gray literature. Our search and screening criteria yielded 121 data sources, representing 130 translocation cases. We quantified the association between 15 translocation tactics and short-term translocation outcomes by calculating odds ratios and used forest plots to display results. Snake translocations involved 47 species (from mainly 2 families), and most were motivated by research, were monitored for at least 6 months, occurred in North America, and took place from the 1990s onward. The odds of a positive snake translocation outcome were highest with release of captive reared or juvenile snakes, release of social groups together, delayed release, provision of environmental enrichment or social housing before release, or minimization of distance translocated. The odds of a positive outcome were lowest when snakes were released early in their active season. Our results do not demonstrate causation, but outcomes of snake translocation were associated with 8 tactics (4 of which were strongly correlated). In addition to targeted comparative studies, we recommend practitioners consider the possible influence of these tactics when planning snake translocations. 相似文献
53.
Non-point-source (NPS) pollution remains the primary source of stream impairment in the United States. Many problems such
as eutrophication, sedimentation, and hypoxia are linked with NPS pollution which reduces the water quality for aquatic and
terrestrial organisms. Increasingly, NPS pollution models have been used for landscape-scale pollution assessment and conservation
strategy development. Our modeling approach functions at a scale between simple landscape-level assessments and complex, data-intensive
modeling by providing a rapid, landscape-scale geographic information system (GIS) model with minimal data requirements and
widespread applicability. Our model relies on curve numbers, literature-derived pollution concentrations, and land status
to evaluate total phosphorus (TP), total nitrogen (TN), and suspended solids (SS) at the reach scale. Model testing in the
Chesapeake Bay watershed indicated that predicted distributions of water quality classes were realistic at the reach scale,
but precise estimates of pollution concentrations at the local scale can have errors. Application of our model in the tributary
watersheds along Lake Ontario suggested that it is useful to managers in watershed planning by rapidly providing important
information about NPS pollution conditions in areas where large data gaps exist, comparisons among stream reaches across numerous
watersheds are required, or regional assessments are sought. 相似文献
54.
The authors commence by discussing the role of the United Nations (UN) Commission on Sustainable Development (CSD) in relation to the field of education. The report of the UN Secretary-General to the CSD, Promoting Education, Public Awareness and Training is then evaluated. Novel proposals for the development of an Education 21 programme and for the designation of the educational community as a major group are outlined and advocated. The paper concludes with sections on what was achieved and what remains to be done; recommendations for action are made. 相似文献
55.
Using a probabilistic approach in an ecological risk assessment simulation tool: test case for depleted uranium (DU) 总被引:1,自引:0,他引:1
A probabilistic approach was applied in an ecological risk assessment (ERA) to characterize risk and address uncertainty employing Monte Carlo simulations for assessing parameter and risk probabilistic distributions. This simulation tool (ERA) includes a Window's based interface, an interactive and modifiable database management system (DBMS) that addresses a food web at trophic levels, and a comprehensive evaluation of exposure pathways. To illustrate this model, ecological risks from depleted uranium (DU) exposure at the US Army Yuma Proving Ground (YPG) and Aberdeen Proving Ground (APG) were assessed and characterized. Probabilistic distributions showed that at YPG, a reduction in plant root weight is considered likely to occur (98% likelihood) from exposure to DU; for most terrestrial animals, likelihood for adverse reproduction effects ranges from 0.1% to 44%. However, for the lesser long-nosed bat, the effects are expected to occur (>99% likelihood) through the reduction in size and weight of offspring. Based on available DU data for the firing range at APG, DU uptake will not likely affect survival of aquatic plants and animals (<0.1% likelihood). Based on field and laboratory studies conducted at APG and YPG on pocket mice, kangaroo rat, white-throated woodrat, deer, and milfoil, body burden concentrations observed fall into the distributions simulated at both sites. 相似文献
56.
Langdon CJ Piearce TG Meharg AA Semple KT 《Environmental pollution (Barking, Essex : 1987)》2003,124(3):361-373
Chemical pollution of the environment has become a major source of concern. In particular, many studies have investigated the impact of pollution on biota in the environment. Studies on metalliferous contaminated mine spoil wastes have shown that some soil organisms have the capability to become resistant to metal/metalloid toxicity. Earthworms are known to inhabit arsenic-rich metalliferous soils and, due to their intimate contact with the soil, in both the solid and aqueous phases, are likely to accumulate contaminants present in mine spoil. Earthworms that inhabit metalliferous contaminated soils must have developed mechanisms of resistance to the toxins found in these soils. The mechanisms of resistance are not fully understood; they may involve physiological adaptation (acclimation) or be genetic. This review discusses the relationships between earthworms and arsenic-rich mine spoil wastes, looking critically at resistance and possible mechanisms of resistance, in relation to soil edaphic factors and possible trophic transfer routes. 相似文献
57.
Trevor A. Byer 《Natural resources forum》1979,3(2):117-132
The analysis shows the impact of the 'New International Energy Order' on Jamaica, a developing country almost totally dependent on imported oil for satisfying national energy demand. The energy supply/demand situation between 1961 and 1976 and the structure of energy consumption by major sectors of the economy are discussed. The high income elasticity of commercial energy demand and the increase in the energy intensity of the economy is directly related to expansion of the alumina industry. The structural problems of decoupling GDP and energy growth are indicated. In particular, the impact of the 'New Energy Order' on the development prospects of major bauxite/alumina producing countries which are deficient in indigenous primary energy resources is assessed. Finally, the indigenous resource base is outlined and the major elements of the five-year (1978–1982) national energy plan summarized. 相似文献
58.
Chemically mediated communication is common in spiders but has been poorly studied in burrowing tarantulas. This study aimed
to determine whether chemical cues influence the behaviour of females of Brachypelma vagans, a Mexican species of tarantula, during encounters with previously inhabited burrows or with extracts from the silk of conspecific
females. In laboratory choice tests, female tarantulas entered a burrow that had previously been inhabited by a conspecific
female significantly more frequently than a burrow that had never been inhabited. The identity of the previous inhabitant
also affected the number of spiders that chose to enter a burrow. Spiders were quicker to choose and enter a burrow previously
inhabited by themselves than a burrow previously inhabited by a conspecific or a burrow that had not been previously inhabited.
Hexane, methanol and dichloromethane extracts of conspecific silk elicited different responses from female tarantulas when
extracts were placed on filter paper disks at one end of an experimental arena with a control filter paper disk, on to which
the corresponding solvent alone had been pipetted, placed on the other end of the arena. Spiders showed the strongest responses
to hexane extracts of silk, with a significant preference to move towards the hexane extract and a significantly greater period
of time spent in proximity to the hexane extract compared to the control disk. Overall and in contrast to expectations, tarantulas
were most strongly attracted to the cues left by other conspecific females. As encounters between B. vagans females usually lead to aggression and mortality of one of the participants, we conclude that chemical cues are not signals
that are deliberately released by burrow-inhabiting females but may inadvertently escape and cannot be easily suppressed. 相似文献
59.
Characterization of environmental water samples using strontium and lead stable isotope compositions
A simple procedure using both cation and anion exchange chromatography has been applied in the study of lead and strontium isotope composition in rain and stream water samples from remote catchments in Scotland. Whereas the soil released strontium to stream waters, lead was removed from rain water and the concentrations in stream waters were very low. Highly precise analysis by thermal ionisation mass spectrometry proved necessary in the determination of strontium isotope composition. The 87Sr/86Sr ratio in rain water was close to that of marine strontium but the ratios in stream waters were constant and highly characteristic for the stream. In the case of the stream at the Sourhope site, the ratio (0.70798 ± 0.00005) was less than that in rain water and probably resulted from the weathering of one specific mineral. The results suggested that the 87Sr/86Sr ratios could be used as a stable isotope tracer of waters and to provide information on the weathering processes. Two major anthropogenic components of lead were identified in water samples. One had its origin in petrol additives whereas the other was probably of industrial origin. The low 206Pb/207Pb ratios observed in stream waters confirmed the lead as being of anthropogenic origin and the data suggested that there was a movement, albeit very small, of lead from the soil to waters. 相似文献
60.