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81.
Michael Simone-Finstrom Joel Gardner Marla Spivak 《Behavioral ecology and sociobiology》2010,64(10):1609-1617
Honeybees harvest and use plant resins in a mixture called propolis to seal cracks and smooth surfaces in the nest architecture.
Resins in the nest may be important in maintaining a healthy colony due to their antimicrobial properties. This study had
two main objectives: (1) Provide initial insight on the learning capabilities of resin foraging honeybees; (2) analyze the
sensitivity of resin foraging honeybees to tactile stimuli to elucidate its possible role as a mechanism behind resin foraging.
The first objective provides insight into the phenotype of these bees as compared to other forager types, while the second
creates a starting point for further work on behavioral mechanisms of resin foraging. Using tactile proboscis extension response
conditioning, we found that resin foragers learned to associate two different tactile stimuli, the presence of a gap between
two plates and a rough sandpaper surface, with a sucrose reward significantly better than pollen foragers. The results of
differential tactile conditioning exhibited no significant difference in the ability of resin foragers to discriminate between
smooth and rough surfaces as compared to pollen foragers. We also determined that the sucrose response thresholds (SRTs) of
returning resin foragers were lower compared to returning pollen foragers, but both resin foragers and pollen foragers learned
a floral odor equally well. This is the first study to examine SRTs and conditioning to tactile and olfactory stimuli with
resin foraging honeybees. The results provide new information and identify areas for future research on resin collectors,
an understudied foraging phenotype. 相似文献
82.
The long-term performance of laboratories is examined using results from three proficiency testing programmes in the water and environmental monitoring sector. A medium term proficiency test pass rate of greater than approximately 75% is suggested as a minimum target for routine analysis to demonstrate fitness for purpose. This pass rate is proposed as a practical yardstick to be used by QA managers and accreditation bodies. This recommendation is contingent on a laboratory's continued and largely uninterrupted participation in a PT programme. 相似文献
83.
Petrorhagia nanteuilii (Childing Pink), a nationally rare annual, exists at only one location in the UK on the vegetated shingle spits at Pagham Harbour, West Sussex. Primarily found in dry grassland habitats throughout Spain and Portugal, at present its only known threat in the UK is the invasive perennial, Centranthus ruber (Red Valerian); however for conservation of Petrorhagia nanteuilii to be sustainable, its presence at Pagham Harbour must be better understood. The aim of this study was therefore to investigate the local distribution and ecological associations of Petrorhagia nanteuilii in order to understand the relationships between Petrorhagia nanteuilii and the vegetated shingle communities and thereby inform their conservation. Field surveys of the shingle flora were undertaken in 2007 and 2011. Vegetation was sampled and the edaphic and physical environment was also investigated using TWINSPAN, multivariate analyses and GIS. The results of the study show that Petrorhagia nanteuilii has little association with the true vegetated shingle communities on the shingle spits. They also reveal that in recent years the species has spread rapidly across parts of the site due to a number of adaptations aiding its survival and recent shifts in conservation management that have influenced spit morphology. The ecological disconnection that exists between Petrorhagia nanteuilii and the true shingle communities means it is unlikely that management strategies will be conflicting. The study concludes that conservation of both is feasible, however for management to be sustainable, both short-term and long-term strategies must be considered. 相似文献
84.
James Nelson Rachel Wilson Felicia Coleman Christopher Koenig Doug DeVries Chris Gardner Jeff Chanton 《Marine Biology》2012,159(2):365-372
Seagrass meadows are among the most productive ecosystems in the marine environment. It has been speculated that much of this
production is exported to adjacent ecosystems via the movements of organisms. Our study utilized stable isotopes to track
seagrass-derived production into offshore food webs in the northeastern Gulf of Mexico. We found that gag grouper (Myctereoperca microlepis) on reefs as far as 90 km from the seagrass beds incorporate a significant portion of seagrass-derived biomass. The muscle
tissue of gag grouper, a major fisheries species, was composed on average of 18.5–25% seagrass habitat-derived biomass. The
timing of this annual seagrass subsidy appears to be important in fueling gag grouper egg production. The δ34S values of gag grouper gonad tissues varied seasonally and were δ34S depleted during the spawning season indicating that gag utilize the seagrass-derived biomass to support reproduction. If
such large scale trophic subsidies are typical of temperate seagrass systems, then loss of seagrass production or habitat
would result in a direct loss of offshore fisheries productivity. 相似文献
85.
Biochemical genetic variation at a leucine aminopeptidase (LAP) locus is related to salinity variation in several marine
bivalve molluscs. This paper details an investigation of the Long Island Sound model of LAP selection (LAP genotype-dependent
mortality occurring among newly settled Mytilus edulis mussels) carried out in 1997 among three M. galloprovincialis mussel populations along the salinity gradient of Wellington Harbour, New Zealand. Significant LAP genotypic heterogeneity
was observed at the LAP locus between small (<25 mm shell length) and large (>25 mm shell length) M. galloprovincialis from Petone and Eastbourne (the two sites experiencing the greatest salinity variation), whereas genotypic heterogeneity
was not significantly different between small and large mussels from Seatoun (the site experiencing the least salinity variation).
The Lap
3 allele decreased in frequency and the Lap
4 allele increased in frequency at Petone and Eastbourne, whereas the Lap
3 and Lap
4 allele frequencies remained effectively constant at Seatoun. Both these findings are consistent with the Long Island Sound
model of selection. At all three locations, the Lap
3,3 genotype decreased in frequency from small to large mussels, whereas the Lap
3,4 genotype increased in frequency from small to large mussels. All other LAP genotypes occurred at low frequencies (<0.10)
at all three locations and showed no evidence of frequency change from small to large-size mussels nor evidence of clinal
change among the three locations. These genotype frequency data possibly indicate that the Lap
3,3 genotype is at a selective disadvantage compared to the Lap
3,4 genotype at all three locations, and that this selective disadvantage is related to the extent of salinity variation which
exists at each location. Further investigation is required before it can be determined if the Long Island Sound model of selection
best describes the size-dependent and location-specific changes in LAP allele and genotype frequencies along this salinity
gradient. Comparison of the population genetic structure at the LAP locus in 1995 and in 1997 revealed a profound change from
heterozygote excesses to heterozygote deficiencies for all three M. galloprovincialis populations. The reason for the change is unknown, but the change indicates that population genetic structure at the LAP
locus is highly variable in time, but consistent in space, among these M.␣galloprovincialis populations.
Received: 5 February 1998 / Accepted: 27 May 1998 相似文献
86.
转向世界粮食市场
与严重依赖外国石油的状况形成鲜明对照的是,中国和印度如今在粮食方面处于自给自足的状态,并为它们的成就而自豪(图1-2).这两个国家都经历过严重饥荒的困难历史,都不希望这一悲剧情况重演.自从1985年以来,中国进口的粮食从来没有超过其消费总量的6%,而印度进口的粮食也没有超过其消费总量的3%(表1-3).但是,在未来的几十年内,这两个大国是否可以避免求助于全球粮食市场(主要指小麦、水稻、玉米和其他主要基本食品),已成为这两个国家和全球的一个尚待解决的、重要的问题.这是由于:世界粮食市场与石油市场的状况一样,与20世纪比较,指望生产过剩已经远非那么可靠了. 相似文献
87.
In several marine bivalve species, biochemical genetic variation at a leucine aminopeptidase (LAP) locus is associated with
environmental variability, primarily salinity fluctuation. Population genetic variation at a LAP locus was investigated here
in two sympatric mussel species (Mytilus galloprovincialis and Perna canaliculus) from three locations along a salinity gradient in Wellington Harbour, New Zealand. The data for M. galloprovincialis and P. canaliculus do not support the hypothesis that the LAP polymorphism in either species is associated with salinity variation among adult
mussels. Due to the absence of small mussels among the samples it is not possible to discount the hypothesis that selection
acts primarily against juveniles, as it does for M. edulis in Long Island Sound, USA. Wellington Harbour populations of M. galloprovincialis exhibited large and often highly significant heterozygote excesses at the LAP locus, whereas populations of P. canaliculus from the same locations exhibited large and highly significant heterozygote deficiencies. The reason for this inter-specific
difference in population structure is unknown. If it is the result of selection, this suggests that selection acts differentially
upon the two species, because demographic attributes and reproductive biology are very similar in the two species. For both
M. galloprovincialis and P. canaliculus, significant levels of population genetic heterogeneity were recorded among three locations separated by only 8 to 12 km.
Neither species exhibited shell length-dependent genetic variation at the LAP locus, suggesting that for these two species
the LAP polymorphism is not associated with variation in shell length.
Received: 30 December 1996 / Accepted: 6 January 1997 相似文献
88.
Mussel samples were collected at 4 to 6 wk intervals throughout 1987 from two hybridMytilus edulis/M. galloprovincialis populations, at Croyde Bay and Whitsand Bay, in southwest England. These were analyzed at two polymorphic loci which are diagnostic for allozyme differences which typifyM. edulis andM. galloprovincialis. Dry mantle weight as a function of shell length was determined for all individuals of each sample. Size-frequency data for the two populations was obtained in September 1987 and March 1988. For all genotypes at both sites, fecundity was a function of shell length, and in both populations the frequency ofM. galloprovincialis alleles was positively correlated with shell length. At both sites, allozyme genotype explained a significant amount of variation in mantle weight either when assessed as a main effect or when assessed as an interaction with shell length or time of collection. At Croyde,M. galloprovincialis mussels had greater estimated fecundity per unit length than theM. edulis mussels. Differences in the timing of spawning activity between theM. edulis and theM. galloprovincialis mussels were inferred, and these differences might act to reduce the amount of interbreeding at Croyde. At Whitsand, a reduced level of variability in the timing of spawning activity and fecundity between the genotypes was observed and explained by a higher degree of genetic mixing. Because theM. galloprovincialis mussels had (1) a greater estimated fecundity at any length, and (2) a greater mean length than theM. edulis mussels, the mean genotypic annual fecundity perM. galloprovincialis mussel was 2.8 times greater than an individualM. edulis mussel at Croyde, and 2.2 times greater than an individualM. edulis mussel at Whitsand. This evidence thatM. galloprovincialis mussels have an advantage in fecundity, and thus perhaps in fertility, taken together with the evidence thatM. galloprovincialis also has a higher viability, indicates directional selection in favour of theM. galloprovincialis phenotype. Because of the observed temporal stability of the population it seems likely that this selection is counterbalanced by a massive imigration ofM. edulis spat from neighbouring populations. 相似文献
89.
Polycyclic aromatic hydrocarbons (PAH) were analyzed in surficial sediments and benthic organisms in southwestern Lake Erie near a large coal fired power plant. Sediment concentrations (530–770 ppb PAH) were relatively homogenous throughout most of the 150 km2 area, although river and nearshore concentrations reached nearly 4 ppm. Oligochaete worms and chironomid midges were near equilibrium with local sediments except for enhanced concentrations in nearshore midges. 相似文献
90.
This research examined community acceptance of policy instruments that could be used to promote ongoing maintenance of domestic rainwater tank systems. Using an online survey of 533 tank owners in South East Queensland, Australia, the research investigated four sets of factors that influence policy acceptance: features of the policy, judgements of policy fairness and effectiveness, contextual framing, and individual attitudes and motivations towards tank maintenance. An experimental design incorporating choice modelling was employed. Results demonstrated that perceptions of policy fairness and effectiveness are important to acceptance. Policies that include enabling features associate with increased perceptions of effectiveness, and policies that use incentives are linked to increased perceptions of both fairness and effectiveness. Individual attitudes and motivations regarding tank maintenance were significant predictors of policy support. Perceptions of a person's own ability to undertake tank maintenance tasks were negative predictors of policy intervention, suggesting that people who believe they can carry out maintenance themselves may not see the need for a policy that encourages tank maintenance to exist. The findings are discussed in relation to issues of policy design. 相似文献