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891.
Sexual selection theory predicts that female choice may favour the evolution of elaborate male signals. Darwin also suggested that sexual selection can favour elaborate receiver structures in order to better detect sexual signals, an idea that has been largely ignored. We evaluated this unorthodox perspective by documenting the antennal lengths of male Uraba lugens Walker (Lepidoptera: Nolidae) moths that were attracted to experimentally manipulated emissions of female sex pheromone. Either one or two females were placed in field traps for the duration of their adult lives in order to create differences in the quantity of pheromone emissions from the traps. The mean antennal length of males attracted to field traps baited with a single female was longer than that of males attracted to traps baited with two females, a pattern consistent with Darwin’s prediction assuming the latter emits higher pheromone concentrations. Furthermore, younger females attracted males with longer antennae, which may reflect age-specific changes in pheromone emission. These field experiments provide the first direct evidence of an unappreciated role for sexual selection in the evolution of sexual dimorphism in moth antennae and raise the intriguing possibility that females select males with longer antennae through strategic emission of pheromones. 相似文献
892.
This is the first report of gynandromorphy in Isoptera. An Asian dry-wood termite, Neotermes koshunensis (Shiraki) [Kalotermitidae], possessing both male and female phenotypic characteristics, was found on Okinawa Island, Japan. This deformed individual showed morphological and anatomical hermaphroditism in the abdomen. The right side of the seventh sternite was the female form and contained an ovary, while the left side was the male form and contained a testis. Genotypic analysis revealed that this individual was a genotypic bilateral chimera. These results suggested that the termite was a bilateral gynandromorph with a male left side and a female right side. As reported previously in other insects, double fertilization (by two sperms, one with an X and one with a Y chromosome) of a binucleate egg is the most likely mechanism that generated this genotypic bilateral chimera. N. koshunensis has the ability to reproduce through parthenogenesis, in which the secondary polar body is likely to be used for nuclear phase recovery. If the second polar body in this mechanism has high fertility and healthy embryogenic potential, like an egg nucleus, some of gynandromorphs might be produced by a side effect of parthenogenetic ability. 相似文献
893.
To explore the role of the volatiles emitted from male labial gland (LG) of the bumblebee Bombus ardens ardens, we investigated the responses of virgin queens and males to volatiles using a gas chromatography–electroantennographic detector (GC–EAD) system and Y-tube olfactometer. GC–EAD analysis revealed that citronellol, the main compound detected in the male LG, caused clear electrophysiological responses in the antennae of B. a. ardens virgin queens and males although two minor compounds elicited antennal responses when applied in a high concentration. Behavioral tests using a Y-tube olfactometer showed that queens and males were significantly attracted to both LG extracts and citronellol more than to the solvent alone. This is the first study to demonstrate that citronellol as a major compound of male scent-marking pheromone in B. a. ardens functions as a sex attractant for queens. The results also suggest that this compound has another function as a trail marker used by males. 相似文献
894.
Hummingbird with modern feathering: an exceptionally well-preserved Oligocene fossil from southern France 总被引:1,自引:0,他引:1
Louchart A Tourment N Carrier J Roux T Mourer-Chauviré C 《Die Naturwissenschaften》2008,95(2):171-175
Hummingbirds (Trochilidae) today have an exclusively New World distribution, but their pre-Pleistocene fossil record comes from Europe only. In this study, we describe an exceptionally preserved fossil hummingbird from the early Oligocene of southeastern France. The specimen is articulated, with a completely preserved beak and feathering. Osteological characters allow to identify it as Eurotrochilus sp. This genus is a stem group representative of Trochilidae and was recently described from the early Oligocene of southern Germany. The new fossil reveals that these European Trochilidae were remarkably modern in size, skeletal proportions and the shape of the wing, tail and beak and hyoid bones. These features confirm the early acquisition of the abilities of hovering and nectarivory in hummingbirds, probably before the Oligocene. In several morphological characteristics, they resemble members of the 'true hummingbirds' (subfamily Trochilinae) and differ from hermits (Phaethornithinae). These features, which include a short and square tail and a moderately long, almost straight beak, appear to be primitive within the family Trochilidae. 相似文献
895.
Kevin Shirley Eric Marland Jenna Cantrell Gregg Marland 《Mitigation and Adaptation Strategies for Global Change》2011,16(3):325-346
We recognize that carbon-containing products do not decay and release CO2 to the atmosphere instantaneously, but release that carbon over extended periods of time. For an initial production of a
stock of carbon-containing product, we can treat the release as a probability distribution covering the time over which that
release occurs. The probability distribution that models the carbon release predicts the amount of carbon that is released
as a function of time. The use of a probability distribution in accounting for the release of carbon to the atmosphere realizes
a fundamental shift from the idea that all carbon-containing products contribute to a single pool that decays in proportion
to the size of the stock. Viewing the release of carbon as a continuous probabilistic process introduces some theoretical
opportunities not available in the former paradigm by taking advantage of other fields where the use of probability distributions
has been prevalent for many decades. In particular, theories developed in the life insurance industry can guide the development
of pricing and payment structures for dealing with the costs associated with the oxidation and release of carbon. These costs
can arise from a number of proposed policies (cap and trade, carbon tax, social cost of carbon, etc), but in the end they
all result in there being a cost to releasing carbon to the atmosphere. If there is a cost to the emitter for CO2 emissions, payment for that cost will depend on both when the emissions actually occur and how payment is made. Here we outline
some of the pricing and payment structures that are possible which result from analogous theories in the life insurance industry.
This development not only provides useful constructs for valuing sequestered carbon, but highlights additional motivations
for employing a probability distribution approach to unify accounting methodologies for stocks of carbon containing products. 相似文献
896.
Groundwater is the main source of drinking water and water for agricultural and industrial usage. Therefore, groundwater contamination is prevented and contaminated groundwater is remediated to protect public health and the environment. Methods to remediate groundwater contamination have been recently developed. The use of redox processes in water remediation technologies has not been properly reviewed. Numerous water remediation technologies, such as ultrasonication, bioremediation, electrokinetics and nanotechnology, are closely related to redox processes. Redox processes control the chemical speciation, bioavailability, toxicity, mobility and adsorption of water pollutants in environment. Here, we review (1) general introduction of redox processes, (2) applicability of redox processes in water remediation, and (3) catalytic enhancement of redox potentials to explore its wide applicability in environmental remediation. 相似文献
897.
Adult Vinciguerria nimbaria are the main prey of tuna during the tuna fishing season (late autumn and winter) in the equatorial Atlantic (0–4°N, and
~15°W). V. nimbaria trophic behavior in the fishing grounds was studied in relation to hydrobiological factors to determine its role in the trophic
food web. Sampling stations spaced by 20 nautical miles were set up along a 15°W north–south transect from 4°N to 0°40S. At
each station, the temperature and vertical fluorescence profiles were recorded. Nitrate and chlorophyll a analyses were performed on water sampled at different levels in the euphotic zone. Vertical plankton hauls were carried out
at depths of 0–100 and 0–200 m using a standard WP2 net fitted with a 200-μm mesh gauze. Vinciguerria nimbaria adults were collected using a young-fish mid-water trawl net (10 × 15 m opening mouth, 10 mm cod end mesh). The weight of
the stomach contents, the stomach fullness index, the number of prey, the frequency of occurrence and the prey preponderance
were recorded for 20 fish from each haul. An oligotrophic typical tropical structure (TTS) was found between 1° and 4°N where
small zooplankton was relatively abundant above or near the thermocline. In the TTS, V. nimbaria behaved as an epipelagic fish, feeding on the dominant small prey during the daytime. In turn, it was a prey for tuna. In
the equatorial zone, where zooplankton was more abundant than in the north equatorial zone, V. nimbaria behaved as a mesopelagic fish and as an opportunistic mesozooplankton feeder. It consumed a wide range of sizes of food,
feeding on the most abundant species of zooplankton as well as the largest zooplankton species, possibly while migrating towards
the surface in the late afternoon or in the deep layer. 相似文献
898.
When agricultural lands are no longer used for agriculture and allowed to recover its natural vegetation, soil organic carbon
can accumulate in the soil. Measurements of soil organic carbon and aggregate stability changes under various forms of land
use are needed for the development of sustainable systems. Therefore, comparison of soil samples taken from both agricultural
and nearby area close to land-mined fields where no agricultural practices have been done since 1956 can be a good approach
to evaluate the effects of tillage and agriculture on soil quality. The objective of this study was to compare tillage, cropping
and no tillage effects on some soil-quality parameters. Four different locations along the Turkey–Syria border were selected
to determine effects of tillage and cropping on soil quality. Each location was evaluated separately because of different
soil type and treatments. Comparisons were made between non-tilled and non-cropped fallow since 1956 and adjacent restricted
lands that were tilled about every 2 years but not planted (T) or adjacent lands tilled and planted with wheat and lentil
(P). Three samples were taken from the depths of 0–20 and 20–40 cm each site. Soil organic carbon (SOC), pH ,electrical conductivity,
water soluble Ca++, Mg++, CO3-2{\rm CO}_{3}^{-2} and HCO3-{\rm HCO}_{3}^{-}, extractable potassium (K+) and sodium (Na+), soil texture, ammonium (NH4+{\rm NH}_{4}^{+}–N) and nitrate (NO3–N), extractable phosphorous and soil aggregate stability were determined. While the SOC contents of continuous tillage without
cropping and continuous tillage and cropping were 2.2 and 11.6 g kg−1, respectively, it was 30 g kg−1 in non-tilled and non-planted site. Tillage of soil without the input of any plant material resulted in loss of carbon from
the soil in all sites. Soil extractable NO3−N contents of non-tilled and non-cropped sites were greatest among all treatments. Agricultural practices increased phosphorus
and potassium contents in the soil profile. P2O5 contents of planted soils were approximately 20 to 39 times greater than those of non-tilled and non-cropped soils at different
sites. FTIR spectra showed that never tilled sites had greater phenol, carboxylic acid, amide, aromatic compounds, polysaccharide
and carbohydrates than other treatments. 相似文献
899.
Angela Kallhoff 《Journal of Agricultural and Environmental Ethics》2016,29(1):23-34
In political philosophy, citizenship is a key concept. Citizenship is tied to rights and duties, as well as to concepts of social justice. Recently, the debate on citizenship has developed a new direction in focusing on qualified notions of citizenship. In this contribution, I shall defend three claims. Firstly, consumer citizenship fits into the discussion of qualified notions of citizenship. Secondly, the debate on qualified notions of citizenship cannot be detached from the normative claims in the philosophy of citizenship more generally. In particular, duties and rights receive a distinct shape when debated in terms of “consumer citizenship”. Thirdly, I shall argue that further normative limits can be established by discussing qualified notions of citizenship as items of a list that need to cohere in normative terms. I shall pay particular attention to environmental citizenship. 相似文献
900.
Baoni Xie Xiaoxu Jia Zhanfei Qin Jian Shen Qingrui Chang 《Regional Environmental Change》2016,16(6):1583-1594
Monitoring the dynamics of vegetation growth and its response to climate change is important to understand the mechanisms underlying ecosystem behaviors. This study investigated the relationship between vegetation growth and climate change during the growing seasons on the Loess Plateau in China by analyzing the normalized difference vegetation index (NDVI) derived from the Land Long Term Data Record dataset from 1982 to 2011. Results showed that growing-season NDVI had increased at an annual rate of 0.0028, particularly in the semi-arid and semi-humid regions. By contrast, the NDVI first increased from 1982 to 1994 (0.0013 year?1, P < 0.05) and then decreased from 1994 to 2011 (0.0016 year?1, P < 0.05) in the arid region. Temperature had a positive effect on NDVI in most periods within and across seasons in the semi-humid region but had no significant effect in the arid region. Precipitation had a positive effect on NDVI in the arid region in summer and in the semi-arid region in autumn. Summer precipitation was important for autumn vegetation growth in the arid region, whereas summer temperature increased autumn vegetation growth in the semi-arid and semi-humid regions. Further analyses supported the lag-time effects of climate change on vegetation growth on the Loess Plateau. Precipitation shifts had 15- to 18-month time lag effects on vegetation growth in the three climate regions. Vegetation NDVI had a 17-month lag response to temperature in the semi-arid region. Human activities should not be neglected in analyzing the relationship between vegetation growth and climate change on the Loess Plateau. 相似文献