排序方式: 共有47条查询结果,搜索用时 15 毫秒
31.
松花江水系有机污染的现状及防治对策 总被引:1,自引:1,他引:1
分析了松花江水系有机污染的现状和有机污染的危害,提出了有机污染的防治对策. 相似文献
32.
Male European starlings Sturnus vulgaris sing long complex songs that appear to be important in the courtship of females but which also influence competitive interactions
between males. We tested the hypothesis that females choose mates on the basis of the complexity of their songs, rather than
on the quality of the territories the males defended. In order to determine whether certain territories were preferred over
others, the first set of birds to settle in the experimental nest-boxes was removed and a second set allowed to settle. Consistent
preferences for certain nest-boxes were indicated by correlations between the settlement patterns of the first and second
sets of birds. However, males with the most complex song did not necessarily occupy the most preferred nest sites. Males with
more complex song acquired mates faster. This relationship remained significant when nest-site preference was statistically
controlled, indicating that female starlings chose males with complex song rather than those that defended preferred nest
sites. A number of morphological variables were also found to be uncorrelated with female choice. Song complexity in European
starlings increases with age, and the evolution of song complexity in this species is consistent with an age-indicator model
of sexual selection. Males with larger repertoires were also in better condition, indicating that females obtain high-quality
mates by choosing on the basis of male song.
Received: 29 April 1995/Accepted after revision: 9 September 1995 相似文献
33.
Rindy C. Anderson Stephen Nowicki William A. Searcy 《Behavioral ecology and sociobiology》2007,61(8):1267-1274
Low-amplitude “soft song” is used by a variety of songbirds; in some species during aggressive encounters, in others during
courtship, and yet others in both these contexts. In song sparrows (Melospiza melodia), soft song has thus far been observed only in aggressive encounters, where its production is a more reliable predictor of
attack than any other signaling behavior. We used song playback to test the response of both male and female song sparrows
to soft song. The design of the playback experiments took into account the existence of two classes of soft song: crystallized
soft song, which consists of song types also found in the broadcast repertoire, and warbled soft song, which consists of less-structured
song types not found in the broadcast repertoire. Female song sparrows responded with significantly less courtship display
to the playback of crystallized soft song than to that of normal broadcast song, and response to warbled soft song was if
anything lower than to that of crystallized soft song. Male song sparrows responded equally aggressively to normal broadcast
song as to crystallized soft song, and equally aggressively to warbled soft song as to crystallized soft song. The female
results support the conclusion that neither form of soft song functions in courtship. The male results suggest that the reliability
of soft song as a signal of aggressive intent is not maintained by a receiver retaliation rule. 相似文献
34.
刘双怡 《防灾技术高等专科学校学报》2010,(3):114-119
地震灾害是给人类社会造成极大破坏的自然灾害之一。根据《宋史》等书记载,对宋代320年间的地震灾害进行初步的统计和分析,以认识两宋地震灾害的基本状况。地震发生后,宋朝政府积极展开救灾与论政,以帮助灾区度过困难并总结治国方略得失,以增强政府抵御灾害的能力。 相似文献
35.
Ioana Chiver Bridget J. M. Stutchbury Eugene S. Morton 《Behavioral ecology and sociobiology》2008,62(12):1981-1990
Extra-pair fertilizations are common in many socially monogamous species, and paternity studies have indicated that females
may use male vocal performance and plumage ornaments as cues to assess male quality. Female off-territory forays may represent
a key component of female choice and male extra-pair mating success, and female foray behaviour is expected to be strongly
influenced by indictors of male quality. In this study, we examined how male song and ornamentation affect how often females
left their territories, which males they visited and extra-pair paternity in a socially monogamous passerine, the hooded warbler
(Wilsonia citrina). We radiotracked 17 females during the fertile period and quantified male vocal performance (song output and rate) and plumage
characteristics (size of the black melanin hood and colour of the black hood, yellow cheeks and breast areas). We obtained
blood samples and determined paternity at 35 nests including those of 14 females that we radiotracked. Eleven (65%) of the
17 females forayed off-territory, whilst fertile and female foray rate was positively correlated with the number of extra-pair
young in the nest. Females that left their territories more frequently were paired with males that sang at a low rate. In
addition, extra-pair mates had higher song rates than the social mates they cuckolded (5.3 songs/min vs. 4.4 songs/min). Female
off-territory forays or extra-pair paternity were not significantly related to male plumage characteristics. Our results indicate
that a high song rate influences both the foray behaviour of a male’s social mate and the likelihood that he will sire extra-pair
offspring with neighbouring females. 相似文献
36.
C. Doutrelant A. Leitao K. Otter M. M. Lambrechts 《Behavioral ecology and sociobiology》2000,48(2):119-124
A previous study of geographic variation in blue tit (Parus caeruleus) song structure showed that changes in blue tit song syntax (i.e. presence/absence of a trill) are correlated with the breeding
density of a close competitor, the great tit (P. major), and are not correlated with other environmental factors such as vegetation structure or blue tit breeding density. We tested
the hypothesis that blue tit trilled song represents a character shift that evolved because it reduced territorial interactions
with more dominant great tits. We conducted five sets of playback trials in three study populations (mainland southern France,
Corsica and Denmark) presenting male great tits with blue tit trilled and untrilled songs and great tit songs. We found that
great tits respond equally strongly to both blue tit untrilled songs and to great tit songs, but show a significantly weaker
response to blue tit trilled songs. These findings are the first experimental evidence that interspecific competition may
play an important role in macrogeographic variation of bird song.
Received: 10 October 1999 / Received in revised form: 2 April 2000 / Accepted: 15 April 2000 相似文献
37.
两宋时期自然灾害的文学记述与地理分布规律 总被引:2,自引:0,他引:2
两宋320年间共发生灾害1739次,灾害种类14种,如此深重的灾害是导致两宋"积贫积弱,国力不强"的一大主要因素.由于宋朝时期的地理气候特点,水灾、旱灾接连不断发生,并且成为两宋最主要的自然灾害.古代自然灾害研究主要依据史书记载,中国是世界上少数灾害多发的国家之一,文学作品中反映出来的灾难与救世观念可以给人们很多启发.以王禹偁为代表的宋代文学家给后世留下了许多记述灾害的文学作品,从文学作品的记述中可以提取古代灾害的准确信息.北宋都城位于开封,南宋京都在杭州,由于史料对当时中央政府所在地省份的记述颇为翔实,两宋自然灾害的省区分布,以河南、浙江灾害次数最多. 相似文献
38.
The importance of riparian vegetation to support stream function and provide riparian bird habitat in semiarid landscapes
suggests that standardized assessment tools that include vegetation criteria to evaluate stream health could also be used
to assess habitat conditions for riparian-dependent birds. We first evaluated the ability of two visual assessments of woody
vegetation in the riparian zone (corridor width and height) to describe variation in the obligate riparian bird ensemble along
19 streams in eastern Oregon. Overall species richness and the abundances of three species all correlated significantly with
both, but width was more important than height. We then examined the utility of the riparian zone criteria in three standardized
and commonly used rapid visual riparian assessment protocols—the USDI BLM Proper Functioning Condition (PFC) assessment, the
USDA NRCS Stream Visual Assessment Protocol (SVAP), and the U.S. EPA Habitat Assessment Field Data Sheet (HAFDS)—to assess
potential riparian bird habitat. Based on the degree of correlation of bird species richness with assessment ratings, we found
that PFC does not assess obligate riparian bird habitat condition, SVAP provides a coarse estimate, and HAFDS provides the
best assessment. We recommend quantitative measures of woody vegetation for all assessments and that all protocols incorporate
woody vegetation height. Given that rapid assessments may be the only source of information for thousands of kilometers of
streams in the western United States, incorporating simple vegetation measurements is a critical step in evaluating the status
of riparian bird habitat and provides a tool for tracking changes in vegetation condition resulting from management decisions. 相似文献
39.
Sexual selection in the zebra finch Taeniopygia guttata : condition, sex traits and immune capacity 总被引:5,自引:2,他引:3
The aim of this study was to test two hypotheses: (1) that condition-dependent secondary sexual traits reflect an individual's
immune capacity and (2) that immune capacity and secondary sexual traits covary with primary sex traits, specifically ejaculate
quality. We used the zebra finch Taeniopygia guttata as a study species, since the traits that females find attractive in males of this species, song rate and beak colour, are
well established. A paired experimental design comprising 31 pairs of brothers was used; for each pair, one male was assigned
to a control group provided with ad libitum food and no additional exercise, and the other male was assigned to an experimental
group which experienced additional exercise and a reduced rate of food intake. After 11 weeks, the experimental group differed
significantly from the control group in a range of variables, including body mass, haematocrit, granulocyte:lymphocyte (G:L)
ratio and several primary sex traits, indicating that condition in this group was reduced. Birds in the experimental group
showed a differential response to the treatment. We used the rank order in which birds could be captured by an experimenter
as an index of condition. Birds easily caught were assumed to be in poorer condition than those which were more difficult
to capture. Rank capture order was repeatable and was significantly correlated with the G:L ratio in the experimental group,
but not in the control group. In the experimental group, rank capture order was correlated significantly with both secondary
sex traits: birds in better condition had redder beaks and a higher song rate. However, beak colour and song rate did not
covary significantly, suggesting that these two traits provide different types of information. Secondary sex traits did not
covary with primary sex traits or any sperm features. Thus, there was no evidence for Trivers' sexual-competence hypothesis
or the phenotype-linked fertility hypothesis. We used four assays of immune capacity, two general (G:L ratio and spleen mass)
and two specific [antibody titres to sheep red blood cells (SRBCs) and Brucella abortus (BA)]. The G:L ratio was significantly higher in the experimental group, spleen mass (absolute and relative) did not differ
between the groups, anti-SRBC antibody titres were significantly higher in the control group (contrary to expectation), and
anti-BA antibody titres were close to being significantly lower in the experimental group. Within the experimental group,
there was no evidence that antibody titres covaried with secondary sex traits. Although we demonstrated that beak colour and
song rate were condition dependent, our experiment provided no evidence that either of these traits covaried with immune capacity
or sperm features.
Received: 9 February 1998 / Accepted after revision: 5 September 1998 相似文献
40.
Darren McCauley 《Local Environment》2015,20(1):34-49
Activism research is over-reliant on social psychological frameworks emphasising framing or ideological-based explanations. The current underdevelopment of resource-based accounts requires urgent attention from social movement scholars. Stressing the rationality of social movement actors, resource mobilisation theory is used to assess and understand the empirical validity of resource-driven social mobilisation. Anti-genetically modified organism (GMO) activism in France is selected as a uniquely ripe context for exploring resource mobilisation. A resource-based examination reveals why, when and how key anti-GMO movement actors differentiated their strategies on the basis of protest, politics and produce. A new framework is proposed to encompass key variables around material, human and network-based resources. It is argued that resource mobilisation research designs need to move beyond financially driven causal arguments. 相似文献