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91.
Brenda D. Kranz Michael P. Schwarz Taryn E. Wills Thomas W. Chapman David C. Morris Bernard J. Crespi 《Behavioral ecology and sociobiology》2001,50(2):151-161
We present the first life history data for Oncothrips morrisi, a species in a clade of haplodiploid, Australian gall-inducing thrips that has a micropteran fighting morph in the first generation of the gall. Micropterans in other species in the clade have lower fecundity than their mother, and these species are considered eusocial. There is no such reproductive skew in O. morrisi, and the species is not eusocial by any definition. The volume of O. morrisi galls is between 4 and 20 times greater in than eusocial species in the clade and the dispersing-brood size varies between 5 and 15 times larger than that of other species. The lack of skew in O. morrisi could be associated with large gall volume, reducing competition between females for space and feeding sites for their offspring. As O. morrisi is in a lineage basal to eusocial Oncothrips, we also discuss selective factors for the evolution of a non-dispersing fighting morph in this clade. The costs involved in dispersal and latency to reproduction may have lowered the selective threshold for the evolution of a non-dispersing morph. Once non-dispersal evolved, selection to defend one's offspring may have promoted the evolution of soldier-like morphology and behaviour. 相似文献
92.
Exploratory study of suspended sediment concentrations downstream of harvested peat bogs 总被引:1,自引:0,他引:1
Pavey B Saint-Hilaire A Courtenay S Ouarda T Bobée B 《Environmental monitoring and assessment》2007,135(1-3):369-382
Peat bog harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage
water is evacuated towards neighboring rivers, estuaries or coastal waters. High suspended sediment concentrations (SSC) were
found in the drainage water at one particular site during the 2001–2002 spring seasons in New Brunswick (Canada). The main
objective of this study was to verify this observation at other sites, compare SSC levels leaving harvested peat bogs with
those leaving an unharvested bog, and to determine if high SSC events happen only in Spring or all year round. Suspended sediment
concentrations were monitored downstream of three harvested peat bogs and an unharvested reference bog located in New Brunswick
during the ice free seasons of 2003–2004. On average, SSC at the harvested sites exceeded 25 mg/l, which is the recommended
daily maximum concentration, 72% of the time, while the same concentration was exceeded 30% of the time at the unharvested
sites. SSC were found to be significantly higher at harvested sites than at the reference sites for all seasons. The highest
SSC medians were recorded in the Fall but SSC was elevated in all seasons. High SSC levels in receiving waters may be caused
by field ditching activities and insufficient sediment controls. Findings suggest the NB Peat Harvesting 25 mg/l SSC guideline
should be reviewed. 相似文献
93.
A previous report showed that the physical and sanitary quality of hand-dug wells from an oil-producing area of Nigeria was
poor in spite of the presence of well protective features. The hypothesis that handling habits is associated with the well
water quality was therefore, tested. A structured questionnaire with scales for measuring handling habits was administered
to 60 female (>18 years) hand-dug well users/owners randomly selected from three towns in the oil-producing area. The respondents’
wells were analysed for coliform bacteria. The findings showed that poor handling habits were the trend (habit score: Mean,
9.23 vs. 20 total available points). Handling habit indicated by scores, significantly negatively correlated (−0.89; P < 0.01) with coliform counts (indicator of poor sanitary quality). While the data collected and discussions with respondents
indicated awareness of the risk of drinking well water, widespread skepticism of the potential hazards of non-drinking domestic
uses (e.g., cooking, washing of plates, cups, cutleries etc.) was evident. Discontent with some aspects of science was indicated.
It is concluded that there is need for social discourse and more public health campaign aimed at transforming skepticism to
consent. 相似文献
94.
Farwell AJ Vesely S Nero V Rodriguez H McCormack K Shah S Dixon DG Glick BR 《Environmental pollution (Barking, Essex : 1987)》2007,147(3):540-545
The growth of transgenic canola (Brassica napus) expressing a gene for the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase was compared to non-transformed canola exposed to flooding and elevated soil Ni concentration, in situ. In addition, the ability of the plant growth-promoting bacterium Pseudomonas putida UW4, which also expresses ACC deaminase, to facilitate the growth of non-transformed and transgenic canola under the above mentioned conditions was examined. Transgenic canola and/or canola treated with P. putida UW4 had greater shoot biomass compared to non-transformed canola under low flood-stress conditions. Under high flood-stress conditions, shoot biomass was reduced and Ni accumulation was increased in all instances relative to low flood-stress conditions. This is the first field study to document the increase in plant tolerance utilizing transgenic plants and plant growth-promoting bacteria exposed to multiple stressors. 相似文献
95.
96.
97.
During the period from 1996 to 2002, 60,397 vehicles were involved in crashes with property damage and/or injury on a French motorway network of 2000 km. It was observed that 6.7% of these accidents involved tire blow-outs. In 87% of cases, only one vehicle was involved in the accident. Tire blow-outs occurred in 6.5% of cars that represented more than 80% of the vehicles involved in crashes. The occurrence of this phenomenon is very high for vans (22%), though it concerns trucks less (2.5%). The proportion of tire blow-outs decreased from 1997, when it was 8.0%, to 5.9% in 2002. However, two main facts require examination: (1) On inter-urban motorways, crashes involving blow-outs of rear tires occur four times more frequently than for blow-outs of front tires. (2) The frequency of tire blow-outs is especially high for vans, and almost always involves rear tires. This higher frequency for rear tires is the result of two phenomena, which are indistinguishable given the data available: firstly, a four-wheel vehicle is more difficult to control if a blow-out occurs on a rear tire (confirmed experimentally); secondly, rear tires may be in poor condition more often than front tires, and so more prone to blow-outs. Consequently, users are strongly recommended to install the best tires on rear wheels. In practice, if only the front tires are replaced, which often occurs because they tend to be worn out more quickly than the rear ones (especially for front wheel drive vehicles), it is necessary to move the rear tires to the front and fit the new ones on the rear wheels. Very interesting technological developments are in progress that should reduce the number of tire blow-outs. However, considering the time necessary to renew the number of cars on the roads, this very simple and inexpensive recommendation should apply to all cars and especially to vans. 相似文献
98.
M. V. Senat J. P. Bernard A. Delezoide P. Saugier-Veber Y. Hillion J. Roume Y. Ville 《黑龙江环境通报》2001,21(13):1129-1132
Hydrocephalus-stenosis of the acqueduct of Sylvius sequence (HSAS) is characterized by hydrocephalus, macrocephaly, adducted thumbs, spasticity, agenesis of the corpus callosum and mental retardation. X-linked hydrocephalus is known to be due to mutations in the gene coding for the neural cell adhesion molecule L1 (L1-CAM) and diagnosis is made by identification of a mutation in the L1-CAM gene. Prenatal diagnosis of HSAS is usually suggested on ultrasound examination showing hydrocephalus in a male fetus associated with bilateral adducted thumbs. Mutation screening of the L1-CAM gene is indicated when neuropathological examination shows hypoplasia of the corticospinal tract associated with aqueductal stenosis. We report here two cases of HSAS diagnosed within the same family by ultrasound examination in the first trimester of pregnancy when bilateral adducted thumbs were the only early ultrasound marker. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
99.
100.
Facultative joint colony founding by social insects provides opportunities to analyze the roles of genetic and ecological
factors in the evolution of cooperation. Although cooperative nesting is observed in range of social insect taxa, the most
detailed studies of this behavior have been conducted with Hymenoptera (ants, bees, and wasps). Here, we show that foundress
associations in the haplodiploid social thrips Dunatothrips aneurae (Insecta: Thysanoptera) are most often comprised of close relatives (sisters), though groups with unrelated foundresses are
also found. Associations among relatives appear to be facilitated by limited female dispersal, which results in viscous population
structure. In addition, we found that per capita productivity declined with increasing group size, sex ratios were female-biased,
and some female offspring apparently remained in their natal domicile for some time following eclosion. D. aneurae thus exhibits a suite of similarities with eusocial Hymenoptera, providing evidence for the convergent evolution of associated
social and life-history traits in Hymenoptera and Thysanoptera. 相似文献