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241.
242.
植物诱导防御对昆虫种群结构的影响研究 总被引:1,自引:0,他引:1
植物通过自身的诱导防御可以影响昆虫的寄主选择、生长发育,以及捕食性天敌和寄生性天敌对昆虫的追踪与确认。本文总结和回顾植物诱导防御对昆虫种群结构的影响,并对发展前景进行了简单论述。还强调了要从环境、物种相互作用关系以及生态结构的演替过程,总体方向上对植物诱导抗虫性进行全面系统分析,才能更深刻地理解这一理论。 相似文献
243.
为探讨铅暴露对小鼠胸腺T细胞活化后诱导细胞凋亡的影响,将24只健康初断乳21日龄清洁级雄性KM小鼠随机分为4组:对照(蒸馏水)组和低(200 mg·L-1)、中(400 mg·L-1)、高(800 mg·L-1)剂量乙酸铅染毒组,每组6只.采用自由饮水方式进行染毒,连续染毒12周.染毒结束后,分离胸腺细胞,采用脂质体介导法将NFκB、AP-1、NFAT的荧光素酶报告基因转染到胸腺T细胞,刺激48 h后,检测荧光素酶活性.刺激胸腺细胞后,采用流式细胞仪检测凋亡相关膜分子Fas、FasL活性及细胞凋亡率.结果表明,与健康对照组小鼠相比,中、高剂量铅暴露组小鼠胸腺T细胞膜表面Fas及FasL表达明显增强(p<0.05),细胞凋亡率明显增加(p<0.05);相对于刺激前,anti-CD3刺激后各组小鼠胸腺T细胞的NFκB、AP-1、NFAT转录活性明显增加(p<0.05),Fas/FasL的表达明显增强(p<0.05),细胞凋亡率明显增加(p<0.05),但相对于刺激后健康对照组,各剂量铅暴露组小鼠胸腺T细胞3种核因子转录活性明显下降(p<0.05),Fas及FasL表达明显减弱(p<0.05),细胞凋亡率明显降低(p<0.05),且随着染铅剂量增加,均呈现下降趋势. 相似文献
244.
Stephan J. Schoech Ronald L. Mumme John C. Wingfield 《Behavioral ecology and sociobiology》1996,39(2):77-90
To determine whether fundamental differences exist in the reproductive physiology of breeder and nonbreeder Florida scrub-jays
(Aphelocoma coerulescens), we compared plasma levels of testosterone (T) and luteinizing hormone (LH) in males, and estradiol (E2) and LH in females. Although male breeders had higher overall T and larger testes, nonbreeders’ T paralleled that of breeders,
and their testes were more than an order of magnitude larger than regressed testes. Breeder and nonbreeder males had equivalent
baseline LH, and equivalent changes in LH following a gonadotropin-releasing hormone (cGnRH-I) challenge. The T, LH and GnRH
challenge data indicate that nonbreeder males have functional hypothalamo-pituitary-gonadal (HPG) axes. We found no hormonal
evidence of inbreeding suppression in males: nonbreeders that did not live with their mothers and those that did had similar
T. Male nonbreeders that were exposed to E2-implanted females had higher T than did controls, suggesting that the lack of within-pair stimulation is a key factor in
whether an individual delays breeding. Female nonbreeders had E2 titres equal to or higher than breeders and neither basal LH nor LH following GnRH challenge differed by breeding status.
Nonbreeders’ ovarian follicles were smaller than breeders’, but were larger than they would be during the non-breeding season.
These data suggest that nonbreeders were primed for breeding and were simply waiting for an opportunity or a required stimulus.
Female nonbreeders that lived in a territory with an unrelated male breeder had significantly higher E2 than those that remained with their fathers. Similarly, nonbreeders that were captured away from their home territories had
elevated E2. However, nonbreeders that lived with their fathers had E2 that was equivalent to breeding females, suggesting that inbreeding avoidance may not be the primary factor leading to delayed
breeding in females.
Received: 13 June 1995 /Accepted after revision: 27 April 1996 相似文献
245.
通过对大理西湖国家湿地公园所在地洱源县西湖村的种植业、畜禽养殖业、村民生活方式和旅游业的污染现状进行调查和分析,探索西湖村的生产生活与西湖水体污染的关系,比较得出引起西湖富营养化的主要原因是畜禽养殖污染物的流失。针对西湖村水污染源的特点,提出修复和保护西湖环境的措施:改变畜禽养殖方式,解决厩肥随地堆放产生的污染;构建成本低和维护简单的村落污水收集管网和处理系统;建设湿地生态农业和湖滨带乔木-水塘-沟渠生态系统;加强旅游基础设施建设,合理开发旅游资源,以保护促进开发。 相似文献
246.
247.
M. J. O’Riain N. C. Bennett P. N. M. Brotherton G. McIlrath T. H. Clutton-Brock 《Behavioral ecology and sociobiology》2000,48(6):471-477
Meerkats live in co-operatively breeding familial groups in which reproduction is monopolised by a dominant pair of breeders.
Offspring of the breeders are behaviourally subordinate, and typically remain in their natal group as sexually mature, non-breeding
helpers. In this study, we investigated the proximate factors limiting subordinate reproduction. Evidence for reproductive
suppression by dominants was investigated by comparing life history, behaviour and hormonal profiles of dominants and subordinates.
Baseline levels of plasma luteinising hormone (LH) were significantly higher in dominant than in subordinate females. However,
following an exogenous injection of gonadotrophin-releasing hormone (GnRH), both categories had comparable concentrations
of circulating LH. There were no significant differences in pre- or post-GnRH challenge LH levels in dominant or subordinate
males. Reproduction in both dominant and subordinate females rarely occurred in the absence of unrelated males. Given that
groups typically comprise parents and offspring, lack of suitable mates emerged as the primary constraint on subordinate reproduction.
When this constraint was removed, subordinates typically bred but at a lower rate than dominants. This difference in reproduction
may be attributed to intrasexual competition manifested through direct interference by dominant females through subordinate
evictions, infanticide and the abandoning of subordinate litters. We argue that differences in reproductive regulation within
mammalian co-operative breeding systems may be explained by differences in the mating strategy (inbreeding versus outbreeding)
and the probability that subordinates in obligate outbreeding species will encounter unrelated opposite-sex partners.
Received: 19 April 2000 / Accepted: 17 July 2000 相似文献
248.
Reproductive success in a low skew, communal breeding mammal: the banded mongoose, Mungos mungo 总被引:1,自引:1,他引:0
Jason S. Gilchrist 《Behavioral ecology and sociobiology》2006,60(6):854-863
In most cooperatively breeding species, reproduction is monopolised by a subset of group members. However, in some species
most or all individuals breed. The factors that affect reproductive success in such species are vital to understanding why
multiple females breed. A key issue is whether or not the presence of other breeders is costly to an individual’s reproductive
success. This study examines the factors that affect the post-parturition component of reproductive success in groups of communal-breeding
banded mongoose (Mungos mungo), where up to ten females breed together. Per-litter reproductive success was low (only 18% of pups survived from birth to
independence). Whilst singular breeding was wholly unsuccessful, there were costs associated with breeding in the presence
of increasing numbers of other females and in large groups. Synchronisation of parturition increased litter success, probably
because it minimises the opportunity for infanticide or decreases competitive asymmetry between pups born to different females.
There was no evidence of inbreeding depression, and reproductive success was generally higher in litters where females only
had access to related males within their group. I conclude that communal breeding in female banded mongooses represents a
compromise between the benefits of group-living and communal pup care on the one hand, and competition between females to
maximise their personal reproductive success on the other. Such conflicts are likely to occur in most communal breeding species.
Whilst communal breeding systems are generally considered egalitarian, negative effects of co-breeders on individual reproductive
success is still an issue. 相似文献
249.
Effects of Self-Compatibility on the Distribution Range of Invasive European Plants in North America
Abstract: Many plant species have been introduced to new continents, but only a small subset of these have become invasive. It has been predicted that self-compatible species, particularly those that do not need the services of pollinators, are more likely to establish and spread after long-distance dispersal. We tested whether this hypothesis, commonly called Baker's law, applies to 361 species that have invaded the United States from Europe. Species capable of autonomous seed production occurred in significantly more states than species requiring a pollen vector. Moreover, of the species that are not capable of autonomous seed production, self-compatible species occurred in significantly more states than those that are not self-compatible. The positive effect of autonomous seed production on the range of invasion was larger for abiotically pollinated species than for biotically pollinated species and for monocarpic species than for polycarpic species. These results support Baker's law, and we recommend that screening protocols for predicting invasiveness of species considered for introduction should include assessment of their breeding system. 相似文献
250.
Cesar Rodriguez-Saona Therese M. Poland James R. Miller Lukasz L. Stelinski Gary G. Grant Peter de Groot Linda Buchan Linda MacDonald 《Chemoecology》2006,16(2):75-86
Summary. We investigated the volatile emissions of Manchurian ash seedlings, Fraxinus mandshurica, in response to feeding by the emerald ash borer, Agrilus planipennis, and to exogenous application of methyl jasmonate (MeJA). Feeding damage by adult A. planipennis and MeJA treatment increased volatile emissions compared to unexposed controls. Although the same compounds were emitted
from plants damaged by beetles and treated with MeJA, quantitative differences were found in the amounts of emissions for
individual compounds. Adult virgin female A. planipennis were similarly attracted to volatiles from plants damaged by beetles and those treated with MeJA in olfactometer bioassays;
males did not respond significantly to the same volatiles. Coupled gas chromatographic-electroantennogram detection (GC-EAD)
revealed at least 16 antennally-active compounds from F. mandshurica, including: hexanal, (E)-2-hexenal, (Z)-3-hexen-1-ol, 3-methyl-butylaldoxime, 2-methyl-butylaldoxime, (Z)-3-hexen-1-yl acetate, hexyl acetate, (E)-β-ocimene, linalool, 4,8-dimethyl-1,3,7-nonatriene, and E,E-α-farnesene. Electroantennogram (EAG) dose–response curves using synthetic compounds revealed that females had a stronger
EAG response to linalool than males; and male responses were greater to: hexanal, (E)-2-hexenal, (Z)-3-hexen-1-ol, 3-methyl-butylaldoxime, 2-methyl-butylaldoxime, and hexyl acetate. These results suggest that females may
use induced volatiles in long-range host finding, while their role for males is unclear. If attraction of females to these
volatiles in an olfactometer is upheld by field experiments, host plant volatiles may find practical application in detection
and monitoring of A. planipennis populations. 相似文献