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321.
David J. Able 《Behavioral ecology and sociobiology》1999,46(6):423-428
Darwin predicted that scramble competition for access to reproductive females would result in sexual dimorphism of locomotory
structures, but direct evidence for this is extremely rare. I examined the relationship between variation in tailfin size
and mating success in a field and laboratory study of red-spotted newts, Notophthalmus viridescens. Over three breeding seasons, male tailfin size was positively correlated with variation in male amplexus frequency, and
indirectly correlated with male insemination frequency. In a laboratory study, I confirmed that males' ability to capture
females is affected by variation in tailfin size. This is the first study to show that naturally occurring variation in male
locomotory structures affects male mating success. It corroborates the prediction that scramble competition leads to sexual
selection on locomotory structures and, potentially, to dimorphism in these structures.
Received: 16 April 1999 / Received in revised form: 16 May 1999 / Accepted: 12 June 1999 相似文献
322.
In populations of various ant species, many queens reproduce in the same nest (polygyny), and colony boundaries appear to
be absent with individuals able to move freely between nests (unicoloniality). Such societies depart strongly from a simple
family structure and pose a potential challenge to kin selection theory, because high queen number coupled with unrestricted
gene flow among nests should result in levels of relatedness among nestmates close to zero. This study investigated the breeding
system and genetic structure of a highly polygynous and largely unicolonial population of the wood ant Formica paralugubris. A microsatellite analysis revealed that nestmate workers, reproductive queens and reproductive males (the queens' mates)
are all equally related to each other, with relatedness estimates centring around 0.14. This suggests that most of the queens
and males reproducing in the study population had mated within or close to their natal nest, and that the queens did not disperse
far after mating. We developed a theoretical model to investigate how the breeding system affects the relatedness structure
of polygynous colonies. By combining the model and our empirical data, it was estimated that about 99.8% of the reproducing
queens and males originated from within the nest, or from a nearby nest. This high rate of local mating and the rarity of
long-distance dispersal maintain significant relatedness among nestmates, and contrast with the common view that unicoloniality
is coupled with unrestricted gene flow among nests.
Received: 8 February 1999 / Received in revised form: 15 June 1999 / Accepted: 19 June 1999 相似文献
323.
Sexual signalling and viability in a wolf spider (Hygrolycosa rubrofasciata): measurements under laboratory and field conditions 总被引:4,自引:0,他引:4
Janne S. Kotiaho Rauno V. Alatalo Johanna Mappes Silja Parri 《Behavioral ecology and sociobiology》1999,46(2):123-128
This study examined the crucial prediction of the conditional-handicap theory, the relationship between male sexual trait
size and male viability, in the wolf spider Hygrolycosa rubrofasciata. In this species, males court females by drumming dry leaves with their abdomen, and males with the highest drumming rate
enjoy highest mating success. We determined male drumming rate, body mass, and mobility, which reflects mate-searching activity,
in relation to male survival. Because it is often difficult to know how results obtained from laboratory studies reflect the
natural world, particularly when the measured variable is survival, we repeated our study in both laboratory and field conditions.
Males drumming at the highest rate survived better than males drumming at a lower rate in both laboratory and field conditions.
These results are in accordance with the predictions of conditional-handicap models of sexual selection. Survival was independent
of male body mass and there was no significant correlation between male drumming activity and body mass. However, large males
moved further than smaller males, and males moving longer distances lost less mass than those moving shorter distances. These
results suggest that, moving, and consequently mate-searching activity, may be a condition-dependent trait and that there
may be a advantage for large males in mate searching.
Received: 22 October 1998 / Received in revised form: 28 January 1999 / Accepted: 14 February 1999 相似文献
324.
Fluctuating asymmetry (FA) can indicate developmental instability in bilaterally symmetric organisms, and studies have shown
that the degree of asymmetry in male secondary sexual characters influences female mate choice in a number of taxa. In male
Schizocosa ocreata wolf spiders, conspicuous tufts of bristles on the forelegs are a critical component of visual courtship signals, which appear
to play a role in female mate choice. Previous studies have shown that females exhibit reduced receptivity to males with regenerative
asymmetry, a consequence of leg loss and regeneration that causes males to be grossly asymmetric with respect to this important
signaling character. We provide data on the occurrence of FA in the tufts of S. ocreata, and examine further the influence of asymmetry on female mate choice. The distribution of tuft area asymmetry values from
a sample of field-collected males was normal, with a mean value of zero, indicating true FA. For a subset of males measured
directly after field collection and prior to feeding, tuft asymmetry was significantly negatively correlated with measures
of body size (body length) and condition (abdomen volume/cephalothorax width). Receptivity responses of females to visual
signals from live males of similar size varied with the degree of asymmetry in male tufts. Since FA covaries with male body
size and condition, which may also influence behavioral vigor, we used video image manipulation to alter the degree of asymmetry
in tufts of a courting male while holding size and condition constant. Asymmetry treatments represented values within the
range of natural FA variation as well as more extreme values characteristic of regenerative asymmetry. With the confounding
effects of male size, condition, and behavior held constant, female spiders exhibited reduced receptivity responses to all
experimental asymmetric video images relative to a control video stimulus. There were no differences in the frequency of female
receptivity among the various asymmetry treatments, suggesting that discrimination against asymmetry in conspecific male signal
characters is not simply a rejection of extreme phenotypes. Results suggest that asymmetry in a key male secondary character
used in visual signaling, independent of any concomitant behavioral or size factor, is an important criterion in mate choice.
Received: 26 February 1998 / Accepted after revision: 12 September 1998 相似文献
325.
介绍了德兴铜矿对选钼中间矿浓缩溢流水循环利用所采取的措施和所取得的成果。对原钼精矿干燥除尘系统存在问题进行了整治,达到了预期效果。 相似文献
326.
Dilip Kumar Sen Siba Sankar Mahapatra 《International Journal of Sustainable Engineering》2017,10(6):338-357
A novel decision support framework has been proposed herein to solve supplier selection problems by considering green as well as resiliency criteria, simultaneously. An expert team involving a finite number of Decision-Makers (DMs) is to be employed to obtain degree of importance of each of the evaluation criteria and also to assign an appropriate rating for each supplier alternative with respect to the criteria. Since subjective human judgment often bears some sort of ambiguity as well as vagueness, application of fuzzy set theory can be recommended in this context. The present work represents a dominance based decision support system in the light of fuzzy set theory which is basically a simplified version of TODIM and PROMETHEE. It explores dominance between two alternatives with respect to a particular criterion, based on which a global dominance measure is computed to facilitate ranking order of candidate suppliers. The approach proposed in this research seems straightforward which can exclude complex and tedious computational steps of TODIM as well as PROMETHEE. Application potential of the proposed dominance based fuzzy decision-making approach has been compared to that of Fuzzy-TOPSIS and Fuzzy-VIKOR. Good agreement has been observed. In addition to this, the concept of a unique performance index i.e. ‘g-resilient’ (also called ‘ecosilient’) index has been introduced to help in assessing suppliers’ overall performance extent. The work has also been extended to identify the ill (poor)-performing areas in which suppliers are lagging and seek further improvement towards enhancing g-resilient performance level. 相似文献
327.
328.
Sperm allocation in an uncertain world 总被引:3,自引:0,他引:3
Models of optimal sperm allocation are constructed using stochastic dynamic programming techniques, yielding predictions
about sperm allocation when males mate sequentially, breeding time is finite, sperm stores are limited and females vary in
quality. The models suggest that uncertainty of future reproductive opportunities should favour withholding of sperm, so that
males tend to allocate less (for a given level of stored sperm) earlier in the breeding season. This effect is more pronounced
the greater the variance in female quality. We also show that while allocation will be influenced by mate value, it is not
necessarily optimal to allocate preferentially to high-quality females, since the benefits of a higher-quality mate may be
offset by increased risk of rejection of sperm or higher sperm competition. The relationship between mate quality and level
of allocation will depend strongly on the amount of remaining stored sperm, with males whose supplies are depleted being more
likely to favour lower-quality partners.
Received: 12 September 1997 / Accepted after revision: 28 June 1998 相似文献
329.
For intersexual selection to occur, it is necessary that females choose between males. It is now well appreciated that constraints
exist, which preclude females sampling all the available males in a population. These constraints are likely to have caused
the evolution of sampling rules (such as the “best-of-n” rule) by which females sample males. Here we investigate the impact of female subsampling of the male population, not on
the evolution of sampling behaviour, but on the population-level correlation between a male trait and currencies such as reproductive
success. This study is important as it illustrates when population-level correlations can be safely used to infer the presence
and strength of sexual selection in the field. We find that the correlation between a male trait and a mate choice variable
rises steeply as the number of males sampled by each female increases, flattening above seven to ten males sampled. This shape
is found to be remarkably robust, and little affected by, for example, the mate choice variable used, by noise in assessment,
by sampling behaviour depending on female quality, or by population size. The only variable found to have a large impact is
male clumping according to their “quality”. If females are sampling about four males, the maximum correlation that can be
found at the population level is in the range 0.4–0.6, perhaps as little as 0.1 if males are strongly clumped. A recent review
of the literature suggests that four is the average number of males that females sample. Thus, the absence of a strong correlation
cannot by itself be used to infer that sexual selection is weak, as it may be due to females sampling few males.
Received: 18 May 1998 / Accepted after revision: 18 July 1998 相似文献
330.
Changes in male guppy courting distance in response to a fluctuating light environment 总被引:1,自引:0,他引:1
In the guppy (Poecilia reticulata), effective courting by a male requires visual contact with the female. Therefore, environmental light intensity may affect
male display behavior, particularly initial courtship distance. We found that male guppies courted at exact and predictable
distances from the female given a particular light level, both in field and laboratory studies. In lower light levels (<0.1 μmol m−2 s−1), for example at dawn, dusk, or under heavy canopy, males court females at closer and less variable distances (<3 cm). At
higher light levels, which occur during most of the day and with less canopy cover, males often court from twice or three
times further out. Light levels over guppy streams change over relatively short time periods and ranges, correlating with
variation in courtship distances. Laboratory manipulations of irradiance confirmed that courtship distance depends on illumination.
Hence, courtship distances may be set by the effect of lighting on signal efficiency, minimization of energy or time expenditures,
or predation risk.
Received: 16 December 1997 / Accepted after revision: 8 August 1998 相似文献