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771.
Leclaire S Merkling T Raynaud C Giacinti G Bessière JM Hatch SA Danchin E 《Die Naturwissenschaften》2011,98(7):615-624
The importance of olfaction in birds’ social behavior has long been denied. Avian chemical signaling has thus been relatively
unexplored. The black-legged kittiwake provides a particularly appropriate model for investigating this topic. Kittiwakes
preferentially mate with genetically dissimilar individuals, but the cues used to assess genetic characteristics remain unknown.
As in other vertebrates, their body odors may carry individual and sexual signatures thus potentially reliably signaling individual
genetic makeup. Here, we test whether body odors in preen gland secretion and preen down feathers in kittiwakes may provide
a sex and an individual signature. Using gas chromatography and mass spectrometry, we found that male and female odors differ
quantitatively, suggesting that scent may be one of the multiple cues used by birds to discriminate between sexes. We further
detected an individual signature in the volatile and nonvolatile fractions of preen secretion and preen down feathers. These
results suggest that kittiwake body odor may function as a signal associated with mate recognition. It further suggests that
preen odor might broadcast the genetic makeup of individuals, and could be used in mate choice to assess the genetic compatibility
of potential mates. 相似文献
772.
773.
For more than 30 million years, in early Mesozoic Pangea, ??rauisuchian?? archosaurs were the apex predators in most terrestrial ecosystems, but their biology and evolutionary history remain poorly understood. We describe a new ??rauisuchian?? based on ten individuals found in a single locality from the Middle Triassic (Ladinian) Santa Maria Formation of southern Brazil. Nine articulated and associated skeletons were discovered, three of which have nearly complete skulls. Along with sedimentological and taphonomic data, this suggests that those highly successful predators exhibited some kind of intraspecific interaction. Other monotaxic assemblages of Triassic archosaurs are Late Triassic (Norian-Rhaetian) in age, approximately 10 million years younger than the material described here. Indeed, the studied assemblage may represent the earliest evidence of gregariousness among archosaurs, adding to our knowledge on the origin of a behavior pattern typical of extant taxa. 相似文献
774.
Lu Y Beeman RW Campbell JF Park Y Aikins MJ Mori K Akasaka K Tamogami S Phillips TW 《Die Naturwissenschaften》2011,98(9):755-761
We report that the abdominal epidermis and associated tissues are the predominant sources of male-produced pheromones in the
red flour beetle, Tribolium castaneum and, for the first time, describe the stereoisomeric composition of the natural blend of isomers of the aggregation pheromone
4,8-dimethyldecanal (DMD) in this important pest species. Quantitative analyses via gas chromatography–mass spectrometry showed
that the average amount of DMD released daily by single feeding males of T. castaneum was 878 ± 72 ng (SE). Analysis of different body parts identified the abdominal epidermis as the major source of aggregation
pheromone; the thorax was a minor source, while no DMD was detectable in the head. No internal organs or obvious male-specific
glands were associated with pheromone deposition. Complete separation of all four stereoisomers of DMD was achieved following
oxidation to the corresponding acid, derivatization with (1R, 2R)- and (1S, 2S)-2-(anthracene-2,3-dicarboximido)cyclohexanol to diastereomeric esters, and their separation on reversed-phase high-performance
liquid chromatography at −54°C. Analysis of the hexane eluate from Porapak-Q-collected volatiles from feeding males revealed
the presence of all four isomers (4R,8R)/(4R,8S)/(4S,8R)/(4S,8S) at a ratio of approximately 4:4:1:1. A walking orientation bioassay in a wind tunnel with various blends of the four synthetic
isomers further indicated that the attractive potency of the reconstituted natural blend of 4:4:1:1 was equivalent to that
of the natural pheromone and greater than that of the 1:1 blend of (4R,8R)/(4R,8S) used in commercial lures. 相似文献
775.
The coupled SWAP-WOFOST model was used to study the effects of increasing salinity of groundwater, drought and water excess on grass production in The Netherlands. WOFOST simulates crop growth and SWAP simulates transport of water, solutes and heat in the vadose zone. The model was tested using several datasets from field experiments. We applied the models at regional scale where we quantified the impact of various groundwater salinity levels on grass growth and production using historical weather data (1971-2000). The salt concentrations in the subsoil were derived from the National Hydrological Instrument. The results show that salinity effects on grass production are limited. In wet years the excess rainfall will infiltrate the soil and reduce salt water seepage. In a next step we used future weather data for the year 2050, derived from 3 Global Circulation Models. From each model we used data from two CO2 emission scenarios. As expected higher temperatures increased drought stress, however, the production reduction as a result of salt water in the root zone is limited. Salt stress mainly occurred when irrigation was applied with saline water. The increased CO2 concentration in combination with the limited drought stress resulted in increasing simulated actual and potential yields. Overall conclusion for grassland in The Netherlands: drought stress is stronger than stress caused by water excess which on its turn is stronger than salinity stress. Future water demand for irrigation may increase by 11-19% and result in water scarcity if water supply is insufficient. 相似文献
776.
The sympatric neotropical termites Nasutitermes corniger and Nasutitermes ephratae are clearly distinguishable based on morphology, nest architecture, defensive secretion composition, and molecular markers.
However, given the extensive ecological, geographical, and behavioral overlap of these closely related species, the potential
for interbreeding may exist. To explore this possibility, heterospecific pairs were formed experimentally to examine courtship
and colony-establishment behaviors, and reproductive potential. Courtship and nest construction behavior occurred in heterospecific
pairs in a similar manner to that of conspecific pairs. Survival of pairs depended upon the species of the female partner.
N. ephratae females paired with N. corniger males produced as many offspring as conspecific pairs. N. corniger females mated to N. ephratae males, however, produced significantly fewer offspring at 60 days post-establishment than the reciprocal cross or conspecific
N. ephratae or N. corniger pairs. This was also the only pairing in which any aggression was observed. Heterospecific pairs and groups formed in mate
choice mesocosms, suggesting that species recognition between these two termites is not an important aspect of mate choice.
Overall, species mismatch tolerance and hybrid offspring viability are high. The present data, together with previous evidence
from defensive secretions and isozyme analysis, suggest that hybridization may periodically occur in nature, and that reproductive
barriers between these two species may be incomplete. Hybridization could provide a rare but important source of genetic diversity
and may ensure mating opportunities for the more abundant sex of alates in each species. 相似文献
777.
A postanal tail is a major synapomorphy of the phylum Chordata, which is composed of three subphyla: Vertebrata, Cephalochordata,
and Tunicata (Urochordata). Among tunicates, appendicularians are the only group that retains the tail in the adult, and the
adult tail functions in locomotion and feeding in combination with a cellulose-based house structure. Given the phylogenetic
position of tunicates, the appendicularian adult tail may possess ancestral features of the chordate tail. We assess the ultrastructural
development of the tail epidermis of the appendicularian Oikopleura dioica. The epidermis of the larval tail is enclosed by the larval envelope, which is a thin sheet similar to the outer tunic layer
of ascidian larvae. The epidermis of the adult tail seems to bear no tunic-like cellulosic integuments, and the tail fin is
a simple folding of the epidermis. Every epidermal cell, except for the triangular cells at the edge of the tail fin, has
a conspicuous matrix layer of fibrous content in the apical cytoplasm without enclosing membranes. The epidermis of the larval
tail does not have a fibrous matrix layer, suggesting the production of the layer during larval development and metamorphosis.
Zonulae adhaerentes firmly bind the epidermal cells of the adult tail to one another, and the dense microfilaments lining
the cell borders constitute a mechanical support for the cell membranes. The intracellular matrix, cell junctions, and cytoskeletons
probably make the tail epidermis a tough, flexible shell supporting the active beating of the oikopleuran adult tail. 相似文献
778.
Pigeons were released at two sites of equal distance from the loft, one within a magnetic anomaly, the other in magnetically
quiet terrain, and their tracks were recorded with the help of GPS receivers. A comparison of the beginning of the tracks
revealed striking differences: within the anomaly, the initial phase lasted longer, and the distance flown was longer, with
the pigeons' headings considerably farther from the home direction. During the following departure phase, the birds were well
homeward oriented at the magnetically quiet site, whereas they continued to be disoriented within the anomaly. Comparing the
tracks in the anomaly with the underlying magnetic contours shows considerable differences between individuals, without a
common pattern emerging. The differences in magnetic intensity along the pigeons' path do not differ from a random distribution
of intensity differences around the release site, indicating that the magnetic contours do not directly affect the pigeons'
routes. Within the anomaly, pigeons take longer until their flights are oriented, but 5 km from the release point, the birds,
still within the anomaly, are also significantly oriented in the home direction. These findings support the assumption that
magnetically anomalous conditions initially interfere with the pigeons' navigational processes, with birds showing rather
individual responses in their attempts to overcome these problems. 相似文献
779.
Despite having a strong influence on development policies, theories of sustainability have not paid much attention to the capability approach (CA) thus far. Against this backdrop, the present paper argues for the CA’s usefulness of sustainability. In order to avoid just an additional contribution to the already confusing theoretical situation as well as to rely our exploration of the CA’s aptness for a conception of sustainability on a transparent and comparable basis, we will first identify six adequacy conditions for concepts of sustainability. We will then work out a categorial framework for conceptions of sustainability. Finally we will demonstrate how the CA is a promising candidate for filling in the demands of this framework and what further research will be needed. 相似文献
780.
Environmental sustainability in manufacturing is nowadays an urgent and remarkable issue and the main concerns are related to more efficient use of materials and energy.In sheet metal forming processes there is still a lack of knowledge in this field mainly due to the need of a proper modelling of sustainability issues and factors to be taken into account. The aim of this paper is mainly to underline the state of the art from a forming point of view about the sustainability contributions offered in any phase of a product life cycle. Actually, a lack in terms of comprehensive contributions is present in the technical literature, thus, the authors try to give a sort of holistic vision aimed to provide basic guidelines in order to help in identifying the possible solutions with regard to all the phases of a forming product life cycle. The main attention was paid to sheet metal forming technologies. The paper gives an overview of the main topics concerning sheet metal forming problems related to energy and resource efficiency with the aim to stress the principal contributions which may derive from such processes to environmental performances of manufacturing. 相似文献