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排序方式: 共有854条查询结果,搜索用时 453 毫秒
491.
将遗传算法引入定量结构活性关系(QSAR)研究中,对变量进行造反选择,可同时建立几种比较好的QSAR模型,并以交互验证的决定系数作为适应函数,以保证模型质量的可靠性。将其分别应用于氯代酚和单取代苯系列化合物,均得到较好的结果。同时,在这些应用中也反映了遗传算法在变量选择中存在的局限性,限不能保证选择的所有变量在模型中都有显著贡献。 相似文献
492.
Male-male competition ensures honest signaling of male parental ability in the three-spined stickleback (Gasterosteus aculeatus) 总被引:1,自引:0,他引:1
U. Candolin 《Behavioral ecology and sociobiology》2000,49(1):57-61
The importance of socially imposed costs for the evolution and maintenance of honest sexual signals has received less attention
than other costs. Here I show that male-male competition can increase the honesty of sexual signaling in relation to male
parental ability in a species with flexible signaling. When four three-spined stickleback (Gasterosteus aculeatus) males were allowed to court a female first separately and then in competition, red nuptial coloration under competition
reflected male parental ability more accurately than red coloration when separated. Parental ability was determined as the
ability of the male to raise a clutch of eggs to the hatching stage under interaction with other breeding and non-breeding
males. The increased honesty under competition was probably due to subordinate males of poor parental ability decreasing their
color expression under interaction to reduce the risk of fights with superior males. However, socially imposed costs of signaling
were probably not the main factors maintaining honest signaling, as red coloration reflected male parental ability also in
the absence of competition, although less accurately. Nevertheless, the small-scale differences that male-male competition
induced can significantly facilitate adaptive female choice and have large impacts on sexual selection.
Received: 7 July 2000 / Revised: 31 August 2000 / Accepted: 4 September 2000 相似文献
493.
Post-mating odor in females of the solitary bee, Andrena nigroaenea (Apoidea, Andrenidae), inhibits male mating behavior 总被引:3,自引:0,他引:3
We investigated odor changes and their behavioral significance in the solitary, ground-nesting bee Andrena nigroaenea. We used gas chromatography with electroantennographic detection and performed behavioral tests with males in the field using
natural odor samples and synthetic compounds. We found that only cuticle extracts of young females elicited copulation attempts
in the males. We demonstrated that among the 17 compounds which triggered electroantennographic responses, all-trans-farnesyl hexanoate and all-trans-farnesol were significantly more abundant in unattractive cuticle extracts of A. nigroaenea females. Dufour’s gland extracts of these females also contained greater amounts of both compounds. In bioassays using synthetic
farnesyl hexanoate and farnesol we found that these compounds inhibit copulation behavior in the males. Farnesyl hexanoate
is probably synthesized in Dufour’s gland and used by females for lining brood cells. We interpret the semiochemical function
of farnesyl hexanoate and its precursor farnesol to have evolved secondarily. As an outcome of sexual selection, it facilitates
the discrimination by males of receptive females from nesting and thus already mated individuals. The dual function of these
compounds represents an elegant parsimony in the chemical communication system of this insect.
Received: 19 January 2000 / Revised: 29 May 2000 / Accepted: 24 June 2000 相似文献
494.
Limitations to colour-based sexual preferences in three-spined sticklebacks (Gasterosteus aculeatus) 总被引:2,自引:0,他引:2
Female three-spined sticklebacks (Gasterosteus aculeatus) are suggested to select mates based on their red nuptial coloration, males with a redder display being more preferred. Although
there are both laboratory and field data to support this view, there are also published accounts where females do not show
a preference for the redder male. Here we report the results of a series of 19 trials where receptive gravid female three-spined
sticklebacks were allowed to choose between two size-matched rival males. We used photographic and image analysis techniques
to quantify male nuptial coloration to investigate how the magnitude of the colour difference between the two alternative
males influenced female preferences. Using the amount of time a female spent oriented towards each male as a measure of his
attractiveness to her, females were not always found to select the redder of the two presented males. We did, however, find
that that the relative difference in coloration of the two males in each pair was important in determining the level of coloration-based
preference, with females only selecting redder males consistently when the difference in coloration was sufficiently large.
Received: 26 October 1999 / Received in revised form: 10 January 2000 / Accepted: 13 February 2000 相似文献
495.
Hamilton and Zuk proposed that bright plumage in birds indicates genetic resistance to parasites, and that by selecting brighter
males as mates, females can increase their offspring’s fitness due to this inherited resistance. The theory predicts a negative
relationship between parasite load and plumage brightness in males. We used Sindbis virus clearance rate after an experimental
infection to quantify parasite resistance in male greenfinches (Carduelis chloris) and related variation in clearance rate with variation in male plumage brightness. We found that certain aspects of brightness
of the male plumage (i.e. tail-patch area) could be used to predict the virus infection clearance rate. Wing brightness was
uninformative of virus clearance rate, but revealed age class. We found no clear relationship between antibody production
rate and virus clearance rate or total viraemia. However, males with large tail patches tended to have a higher antibody production
rate. The results suggest that the size of the male tail patch may function as an indicator of an individual male’s ability
to resist parasite infections, thus supporting the Hamilton-Zuk theory for a novel taxon of parasites, a virus.
Received: 11 November 1999 / Received in revised form: 13 March 2000 / Accepted: 1 April 2000 相似文献
496.
497.
Mrosovsky N 《Environmental management》2008,41(4):465-467
Translocating sea turtle eggs at risk from high tides to safer places is one of the most widely undertaken conservation measures on behalf of these species. Recent research work has shown that individual female turtles differ in their nest-site preferences. If more of the nests saved by translocation come from turtles with tendencies to lay near the water, might this perhaps interfere with natural selection? This possibility adds to the controversy already surrounding relocation of turtle nests. 相似文献
498.
499.
应用突变评价理论选择采矿方法 总被引:6,自引:0,他引:6
采矿方案的优选是一个复杂的多目标选择问题 ,传统的选择方法是经验类比法 ,且具有很大的主观随意性。笔者应用突变评价理论 ,对采矿系统进行多层目标分解 ,根据归一公式进行量化递归运算 ,分别计算出不同采矿方法的总突变隶属函数值 ,从而确定最优采矿方法。该方法结合实例 ,给出了具体步骤和计算结果 ,并与文献 [6 ]的结果进行比较 ,结论基本相似 ,突变评价法为采矿方案的优化提供了一种新的方法。 相似文献
500.
城市污水处理选址决策及程序设计 总被引:1,自引:0,他引:1
在分析影响城市污水处理场选址的自然及经济因素的基础上,利用层次分析方法构造选址模型.讨论了决策方法及利用计算机进行排序的程序设计步骤,并在IBM-PC机上对实际问题进行了计算. 相似文献