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81.
Melissa Hughes Stephen Nowicki William A. Searcy Susan Peters 《Behavioral ecology and sociobiology》1998,42(6):437-446
One hypothesis for the function of song repertoires is that males learn multiple song types so that they may share songs
with neighbors, allowing them to match during territorial interactions. In at least one song sparrow population, in Washington,
territorial males share a high proportion of song types with their neighbors and use these shared songs in matching. We recorded
song sparrows in Pennsylvania and quantified sharing of whole songs and song segments. We found that song sharing is an order
of magnitude less common in the Pennsylvania population. We found sharing of song segments to be significantly more common
than the sharing of whole songs in three of the five fields we examined, while we found no significant differences between
whole and partial song sharing in the remaining two fields. Finally, we found no evidence that sharing is greater between
birds in the same field compared to birds in different fields. Taken with the data from Washington song sparrows, these results
provide evidence for intraspecific geographic variation in the organization of song repertoires, and suggest that song sharing
has not been a strong selective force in the evolution of song repertoires in song sparrows as a species. Furthermore, Washington
and Pennsylvania song sparrows differ in how they learn song, in that Washington birds copy whole songs, while Pennsylvania
birds appear to copy and recombine song segments, as has been found in laboratory studies of song learning. Thus both song
learning and the function of song repertoires differ between populations of song sparrows. Such intraspecific geographic variation
offers a unique opportunity to explore the ecological and historical factors which have influenced the evolution of song.
Received: 30 June 1997 / Accepted after revision: 8 March 1998 相似文献
82.
A. Peters L. B. Astheimer C. R. J. Boland A. Cockburn 《Behavioral ecology and sociobiology》2000,47(6):438-445
Testosterone has been proposed as a physiological link between the level of sexual signalling and male condition. Bright plumage
is one of the most noticeable sexual signals and is often used by females as a basis for mate choice. Yet bright male plumage
is not necessarily testosterone dependent. We investigated the role of testosterone in the moult into seasonal nuptial plumage
in male superb fairy-wrens. Early pre-nuptial moult is under intense intersexual selection and males can acquire the bright
plumage any time between autumn and the next spring. Testosterone was always undetectable or very low in males in dull eclipse
plumage. During the pre-nuptial moult, both the number of males with detectable testosterone and average testosterone levels
increased sharply. High testosterone was more correlated with nuptial plumage than with presence of the cloacal protuberance
(indicative of sperm storage). Subcutaneous testosterone implants always induced the pre-nuptial moult within 2–3 weeks after
implantation, even well outside the natural time range of moulting. Moreover, removal of the implants before the nuptial plumage
was completed, arrested the moult process. The evidence suggests that development of the nuptial plumage is testosterone dependent,
although we cannot exclude that testosterone exerts its action after conversion to a metabolite such as oestrogen. Once the
nuptial plumage was completed, all males maintained substantially elevated testosterone, sometimes months before the onset
of breeding. These high levels could be necessary to maintain the plumage, and/or are involved in courtship displays. The
results are discussed with respect to potential costs involved in acquiring and maintaining the nuptial plumage.
Received: 17 January 2000 / Received in revised form: 24 February 2000 / Accepted: 25 February 2000 相似文献
83.
84.
A specimen of the horned dinosaur Psittacosaurus from the early Cretaceous of China is described in which the integument is extraordinarily well-preserved. Most unusual is the presence of long bristle-like structures on the proximal part of tail. We interpret these structures as cylindrical and possibly tubular epidermal structures that were anchored deeply in the skin. They might have been used in display behavior and especially if one assumes that they were colored, they may have had a signal function. At present, there is no convincing evidence which shows these structures to be homologous to the structurally different integumentary filaments of theropod dinosaurs. Independent of their homology, however, the discovery of bristle-like structures in Psittacosaurus is of great evolutionary significance since it shows that the integumentary covering of at least some dinosaurs was much more complex than has ever been previously imagined. 相似文献
85.
Jürgen Schnelle-Kreis Martin Sklorz Anette Peters Josef Cyrys Ralf Zimmermann 《Atmospheric environment (Oxford, England : 1994)》2005,39(40):7702-7714
PM2.5 Particle-associated semi-volatile organic compounds (SVOC) were determined in the city of Augsburg, Germany. Daily samples were collected at a central monitoring station from late summer to late autumn 2002. The concentrations of polycyclic aromatic hydrocarbons (PAH), oxidized PAH (O-PAH), n-alkanes, hopanes and long chain linear alkylbenzenes were determined by direct thermal desorption-gas chromatography-time of flight mass spectrometry (DTD-GC-TOFMS). Additionally, PM2.5 particle mass and number concentrations were measured. The sampling campaign can be divided into two parts, distinguished by a lower temperature level in the second part of the campaign. The particulate mass concentration showed no significant changes, whereas most of the SVOC had significant higher mean and peak concentrations in the colder period. The analysis of the data showed an increased influence of non-traffic sources in the colder period, reflected by a weak shift in the PAH profile and a significant shift in the hopane pattern. Statistical analysis of the inter-group correlations was carried out. Eight clusters partly representing different sources of the aerosol have been identified. 相似文献
86.
The foraging ecology of seven Gentoo penguins,Pygoscelis papua, breeding at Ardley Island, Antarctica was studied using animal-attached devices which recorded swimming speed, heading and dive depth. Reconstruction of the foraging routes by vectorial analysis of the data indicated that at no time did the birds forage on the sea bed. Swimming speed was relatively constant at 1.7 m s-1, but rates of descent and ascent in the water column during dives increased with increasing maximum dive depth due to changes in descent and ascent angles. The amount of time spent discending and ascending in the water column increased with maximum dive depth as did the duration spent at the point of maximum depth. Dive profiles were essentially either U-shaped (flat-bottomed dives), or V-shaped (bounce dives). Development of a model based on simple probability theory indicated that the optimal dive profile to maximize the chances of prey acquisition depends on vertical prey distribution and on the visual capabilities of the birds with respect to descent and ascent angles. 相似文献
87.
Janna Peters Jasmin Renz Justus van Beusekom Maarten Boersma Wilhelm Hagen 《Marine Biology》2006,149(6):1417-1429
Seasonal lipid dynamics of the copepod Pseudocalanus acuspes were studied in the Bornholm Basin (Central Baltic Sea) on a monthly basis from March 2002 until March 2003 and were interpreted in light of life cycle strategies and diet selection. The individual total lipid content of females ranged from 0.9 to 1.8 μg, with relative wax ester content reaching a significant maximum in May (44% of total lipids) and minimum (17% of total lipids) in April and November. Significant changes in size, lipid content, lipid classes and fatty acid composition of structural as well as storage lipids suggested five characteristic seasonal phases that were induced by different feeding histories and environmental conditions. Storage lipids were characterized by 18:1(n−9) as major component, which ranged between 44% of total fatty acids in June and 23% in February. The strong coherence between 18:1(n−9) in the seston lipids and the occurrence of ciliates emphasized the importance of ciliates in the diet of P. acuspes. As indicated by changes in the amounts of fatty acid markers, other food sources varied over the year, suggesting an opportunistic feeding behavior. The spring period was characterized by an increase in typical diatom and dinoflagellate markers, whereas other sources, potentially cyanobacteria, became more important during summer. The life cycle strategy is discussed with respect to extant adaptations to high latitudinal habitats. 相似文献
88.
Ultraviolet (UV) reflectance of the plumage is common in birds and plays an important role in sexual signalling. Recently,
it has been proposed that birds are able to modify plumage UV reflectance by the application of uropygial gland secretion.
Based on a survey of the optical properties of this secretion from 51 species belonging to 12 avian orders, we show that two
main types of uropygial secretions exist, one predominantly found in passerines and one in non-passerines, both reducing relative
UV reflectance of a white background (Teflon™ tape). We quantified how each type of secretion (exemplified by blue tit and
mallard) affected feather UV reflectance. Both secretions reduced overall brightness and relative UV reflectance of white
mallard feathers but hardly affected the reflectance of UV/blue blue tit crown feathers. According to models of avian colour
vision, changes in reflectance due to application of the secretion were at or below the discrimination threshold of most birds.
We conclude that the uropygial secretion is unlikely to play a major role in modifying plumage UV reflectance. However, the
optical properties of the uropygial secretion may have been selected to interfere as little as possible with visual signaling
through plumage reflectance.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
89.
90.