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621.
Many animals use chemical signals in sexual selection, but it is not clear how these sexual traits might have evolved to signal honestly male condition. It is possible that there is a trade-off between maintaining the immune system and the elaboration of ornaments. We experimentally challenged the immune system of male Iberian wall lizards, Podarcis hispanica, with a bacterial antigen (lipopolysaccharide), without pathogenic effects, to explore whether the immune activation affected chemical ornaments. Immune activation resulted in decreased proportions of a major chemical in femoral secretions (cholesta-5,7-dien-3-ol = provitamin D(3)) known to be selected in scent of males by females and which active form (vitamin D) has a variety of important effects on immune system function. This result suggests the existence of a potential trade-off between physiological regulation of the immune system and the allocation of essential nutrients (vitamins) to sexual chemical ornaments in male lizards. 相似文献
622.
生态补偿对象的空间选择研究——以甘南藏族自治州草地生态系统的水源涵养服务为例 总被引:5,自引:0,他引:5
生态补偿对象的空间选择研究是生态补偿机制的基础性和支撑性研究,对建立高效合理的生态补偿机制具有十分关键的作用。目前国内在生态补偿的理论和实践研究中很少专门研究补偿对象的选择问题,这种不考虑空间异质性对整个补偿区域实施统一的标准补偿势必会影响到补偿的效率。有鉴于此,基于补偿资金效率考虑,构建以土地所有者提供的生态系统服务、土地所有者的参与成本和生态系统服务受损风险为参数的空间选择模型,以甘南藏族自治州草地生态系统水源涵养服务为例,乡镇为基本研究单元,采用聚类分析法将全州划为五大等级补偿区:优先补偿区、次级优先补偿区、次级补偿区、临界补偿区和潜在补偿区或可能补偿区。对各级补偿区的特征分析结果表明:①草地生态系统的优先补偿主体主要分布在纯牧区,而非优先补偿区主要分布在半农半牧区、林业区和农业区;②基于补偿资金效率考虑的补偿优先度与草地生态系统退化风险呈现高度的吻合状态,草地生态系统的优先补偿区又是高退化风险区(生态脆弱区);③草地生态系统的补偿效率与生态重要性呈现出吻合的状态,即草地生态系统的优先补偿区又是重要生态功能区;④甘南州近17%的草地为低效率和无效率补偿区,也是非生态脆弱区和非重要生态功能区,基于生态脆弱性、生态重要性和补偿效率考虑,这部分草地可暂时给予较低标准的补偿。 相似文献
623.
探讨了ICZs-活性污泥生物系统在控制污泥膨胀过程中的影响因素及其处理效果。3个月的实验结果表明:当ICZs预反应段的条件控制在溶解氧小于0.06mg/L,pH为7-7.6时,该生物系统能够有效控制污泥膨胀。ICZs-活性污泥生物系统具有高效去除污染物的能力。BOD5,COD和TSS总去除率的平均值分别高于97%,80%及90%,其中仅ICZs段在预处理时间为20min时就能去除49.0%-62. 相似文献
624.
生物滴滤池法处理有机废气甲苯工艺填料的选择 总被引:8,自引:0,他引:8
生物滴滤池法处理挥发性有机污染物的研究是世界工业废气净化的前沿热点之一,本研究比较了阶梯环,聚乙烯小球,煤炭渣和某种活性炭附着纤维作为滴滤池中生物附着载体性能的优劣,结果表明,活性炭附着纤维填料系统具有较好的有机污染物去除能力。 相似文献
625.
Simon Garnier Aurélie Guérécheau Maud Combe Vincent Fourcassié Guy Theraulaz 《Behavioral ecology and sociobiology》2009,63(8):1167-1179
We experimentally investigated both individual and collective behavior of the Argentine ant Linepithema humile as they crossed symmetrical and asymmetrical bifurcations in gallery networks. Ants preferentially followed the branch that
deviated the least from their current direction and their probability to perform a U-turn after a bifurcation increased with
the turning angle at the bifurcation. At the collective level, colonies were better able to find the shortest path that linked
the nest to a food source in a polarized network where bifurcations were symmetrical from one direction and asymmetrical from
the other than in a network where all bifurcations were symmetrical. We constructed a model of individual behavior and showed
that an individual’s preference for the least deviating path will be amplified via the ants’ mass recruitment mechanism thus
explaining the difference found between polarized and non-polarized networks. The foraging efficiency measured in the simulations
was three times higher in polarized than in non-polarized networks after only 15 min. We conclude that measures of transport
network efficiency must incorporate both the structural properties of the network and the behavior of the network users. 相似文献
626.
Lydia H. Beaudrot Sonya M. Kahlenberg Andrew J. Marshall 《Behavioral ecology and sociobiology》2009,63(11):1549-1562
Infanticide is widespread among mammals, is particularly common in primates, and has been shown to be an adaptive male strategy
under certain conditions. Although no infanticides in wild orangutans have been reported to date, several authors have suggested
that infanticide has been an important selection pressure influencing orangutan behavior and the evolution of orangutan social
systems. In this paper, we critically assess this suggestion. We begin by investigating whether wild orangutans have been
studied for a sufficiently long period that we might reasonably expect to have detected infanticide if it occurs. We consider
whether orangutan females exhibit counterstrategies typically employed by other mammalian females. We also assess the hypothesis
that orangutan females form special bonds with particular “protector males” to guard against infanticide. Lastly, we discuss
socioecological reasons why orangutan males may not benefit from infanticide. We conclude that there is limited evidence for
female counterstrategies and little support for the protector male hypothesis. Aspects of orangutan paternity certainty, lactational
amenorrhea, and ranging behavior may explain why infanticide is not a strategy regularly employed by orangutan males on Sumatra
or Borneo. 相似文献
627.
The primates of Madagascar (Lemuriformes) are unusual among mammals in that polygynous species lack sexual dimorphism, and
females dominate males socially in most species. Moreover, lemur groups are relatively small and characterized by even adult
sex ratios despite the fact that one male should be able to exclude other males from the group. One hypothesis to explain
this combination of behavioral, morphological, and demographic traits (the “lemur syndrome”) postulates that male–male competition
is relaxed and, hence, variance in male reproductive success is low. Reproductive skew theory provides a framework for testing
this and several related predictions about lemur social evolution. Specifically, low reproductive skew is also predicted if
dominant males or adult females make reproductive concessions to subordinates or if the latter group successfully pursues
alternative reproductive tactics. However, suitable data on paternity, demography, and behavior for a conclusive test of these
predictions have not been available in the past. In this paper, we show that male reproductive success in ten groups of Verreaux’s
sifakas (Propithecus verreauxi) was extremely skewed in favor of the dominant male over 9 years. Our genetic analyses also revealed that more than a third
of all groups are effectively harem groups because only one male was unrelated to the resident female(s). In groups with two
or more non-natal males, the dominant sired 91% of 33 infants. Together, males pursuing one of several alternative reproductive
tactics, such as roaming among several groups or immigrating peacefully, sired only 11% of infants. Thus, female sifakas do
not control group composition by offering reproductive opportunities to subordinate males as staying incentives, intrasexual
selection is not relaxed, and dominant males prevail in a tug-of-war over subordinate males. Because male reproductive skew
in sifakas is even more pronounced than in harem-living anthropoids studied to date, intrasexual selection is clearly not
relaxed, and the lemur syndrome is more puzzling than ever. 相似文献
628.
Peter D. Dijkstra Els M. van der Zee Ton G. G. Groothuis 《Behavioral ecology and sociobiology》2008,62(5):747-755
Mate preferences on male colour have been implicated in generating and maintaining species diversity among haplochromine cichlid
fish. Their lek-like mating system suggests that not only male colour but also territory quality is instrumental in mate choice.
We assessed the relative importance of territory quality and male colour in mate choice by testing whether territory quality
can override the female preference for males of her own colour in the Lake Victoria cichlid genus Pundamilia. First, we showed in experimental groups that the dominant male preferentially monopolised a large tube relative to a small
tube. The situation mimics quality difference in rocky crevices that serves as a focal point for male courtship display. Second,
in mate-choice tests, Pundamilia nyererei females were allowed to choose between closely related P. nyererei and P. pundamilia males; these species differ strikingly in male nuptial coloration, but little else. We gave either both males the same small
tube or one of them a large tube. The preference of P. nyererei females for P. nyererei males in the control situation (where both males had a small tube) was significantly diminished in favour of P. pundamilia males when the latter had the large tube. The results provide experimental evidence that differences in territory quality
can override the female preference for males of her own colour. This finding is critical for a recent hypothesis proposing
that male competition for mating territories can facilitate the process of sympatric speciation by sexual selection. 相似文献
629.
Increasing dietary specialization is an inherently risky strategy because it increases a species’ vulnerability to resource
depletion. However, risks associated with dietary specialization may be offset by increased performance when feeding on preferred
prey. Although rarely demonstrated, highly specialized species are expected to outperform generalists when feeding on their
preferred prey, whereas generalists are predicted to have more similar performance across a range of different prey. To test
this theory, we compared the growth rates of two obligate coral-feeding butterflyfishes (Chaetodon trifascialis and Chaetodon plebeius) maintained on exclusive diets of preferred vs nonpreferred prey. In the field, C. trifascialis was the most specialized species, feeding almost exclusively on just one coral species, Acropora hyacinthus. C. plebeius meanwhile, was much less specialized, but fed predominantly on Pocillopora damicornis. During growth experiments, C. trifascialis grew fastest when feeding on A. hyacinthus and did not grow at all when feeding on less preferred prey (P. damicornis and Porites cylindrica). C. plebeius performed equally well on both A. hyacinthus and P. damicornis (its preferred prey), but performed poorly when feeding on P. cylindrica. Both butterflyfishes select coral species that maximize juvenile growth, but contrary to expectations, the more specialized
species (C. trifascialis) did not outperform the generalist species (C. plebeius) when both consumed their preferred prey. Increased dietary specialization, therefore, appears to be a questionable strategy,
as there was no evidence of any increased benefits to offset increases in susceptibility to disturbance. 相似文献
630.
Reut Loria Inon Scharf Aziz Subach Ofer Ovadia 《Behavioral ecology and sociobiology》2008,62(7):1185-1192
Antlion larvae are sand-dwelling insect predators, which ambush small arthropod prey while buried in the sand. In some species,
the larvae construct conical pits and are considered as sit-and-wait predators which seldom relocate while in other species,
they ambush prey without a pit but change their ambush site much more frequently (i.e., sit-and-pursue predators). The ability
of antlion larvae to evade some of their predators which hunt them on the sand surface is strongly constrained by the degree
of sand stabilization or by sand depth. We studied the effect of predator presence, predator type (active predatory beetle
vs. sit-and-pursue wolf spider), and sand depth (shallow vs. deep sand) on the behavioral response of the pit building Myrmeleon hyalinus larvae and the sit-and-pursue Lopezus fedtschenkoi larvae. Predator presence had a negative effect on both antlion species activity. The sit-and-wait M. hyalinus larvae showed reduced pit-building activity, whereas the sit-and-pursue L. fedtschenkoi larvae decreased relocation activity. The proportion of relocating M. hyalinus was negatively affected by sand depth, whereas L. fedtschenkoi was negatively affected also by the predator type. Specifically, the proportion of individual L. fedtschenkoi that relocated in deeper sand was lower when facing the active predator rather than the sit-and-pursue predator. The proportion
of M. hyalinus which constructed pits decreased in the presence of a predator, but this pattern was stronger when exposed to the active
predator. We suggest that these differences between the two antlion species are strongly linked to their distinct foraging
modes and to the foraging mode of their predators.
Reut Loria and Inon Scharf contributed equally to the paper. 相似文献