首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5篇
  完全免费   1篇
  2011年   2篇
  2009年   1篇
  2005年   1篇
  2003年   1篇
  1999年   1篇
排序方式: 共有6条查询结果,搜索用时 15 毫秒
1
1.
2.
For many marine organisms, the population dynamics in multiple habitats are affected by migration of planktonic larvae. We herein examine the effect of incomplete larval mixing on the condition for species coexistence. The system consists of two heterogeneous habitats, each composed of a number of sites occupied by adults of two species. Larvae produced in a habitat form a pool and migrate to the pool of the other habitat. When an adult dies, the vacant site becomes occupied by an individual randomly chosen from the larval pool. We study (1). the invasibility of a inferior species which has no advantage in either habitats, (2). the dynamics when larval migration and competition among adults are symmetric between habitats, and (3). the case with unidirectional migration. The coexistence of competitors is more likely to occur when larval migration is weak.  相似文献
3.
Population genetics of the mosquito Aedes vigilax (Skuse) (Diptera: Culicidae), a major vector of arboviruses (e.g. Barmah Forest, Ross River), were investigated to obtain an indirect estimate of mosquito dispersal characteristics in typical habitats of Aedes vigilax in south-east Queensland: on the off-shore islands of Moreton Bay and on the mainland where disjunct breeding populations of Ae. vigilax are distributed along intertidal marsh. Six allozyme loci were assessed for genetic differentiation between samples from 11 localities. Significant larval variation between some breeding sites was attributed to site-specific selection. Nonsignificant genetic differentiation was found among collections of adult mosquitoes caught in light traps throughout the study area (exceeding 60x27 km), indicating widespread dispersal. As distances of < or = 9 km over water did not appear to act as effective barriers to Ae. vigilax dispersal, localized control activities applied to Ae. vigilax breeding sites are unlikely to be effective against the vagile adult population. Therefore, the contiguous shires programme of broad acre control is endorsed to prevent the spread of arboviruses carried by Ae. vigilax  相似文献
4.
通过2009,2010年春季对江淮地区安徽凤台麦田及灯诱灰飞虱Laodelphax striatellus(Fallén)种群的系统调查和雌虫卵巢的系统解剖,明确了本地越冬后灰飞虱的种群性质,作为灰飞虱能否迁飞的判据;运用美国NOAA网站的HYSPLIT平台对本地的迁入高峰做了数值模拟和虫源分析。结果表明:(1)江淮稻区灰飞虱麦田种群的迁移动态为远距离迁飞与本地扩散相结合;(2)在本地范围内,灰飞虱的本地繁殖型长翅成虫于麦收前可从麦田向秧田迁移扩散,在不利于长翅成虫起飞进行远距离迁飞的天气条件,如降雨、大风等的影响下,麦田迁飞型种群可向附近的秧田扩散;(3)灯诱与田间长翅雌虫卵巢解剖表明本地2010年6月5日和12日出现迁入虫群;虫源轨迹分析显示2010年6月5日迁入虫峰来自苏中的扬州地区,6月12日迁入虫源来自鲁南济宁地区。  相似文献
5.
苏敏 《生态学报》2011,31(12):3265-3269
景观破碎化和扩散是空间种群模型的重要因素,对生物入侵存在着深远的影响。本章将基于偶对近似模型,探讨由局部和全局宿主-寄生相互作用共同决定的扩散模式对破坏性景观上疾病入侵与传播的影响。其中,生境破坏由生境丧失量与生境破碎化程度来描述。模拟结果显示,宿主和病毒的全局扩散对疾病的入侵与种群密度产生不对称效应:病毒的全局扩散对系统产生的影响较宿主的全局扩散更为显著。不同扩散模式下,生境丧失越高或破碎化程度越低,均将越有害于寄生病毒的入侵;同时,生境的破坏程度也显著地影响了入侵阈值对扩散模式的响应机制。本文研究结果暗示,景观破碎化的空间分布格局以及病毒扩散的限制均可作为物种保护与管理中有效的疾病控制策略。该研究结果在一定意义上丰富和发展了寄生感染理论,为物种保护提供了生态学理论依据。  相似文献
6.
Many self-incompatible plant species exist in continuous populations in which individuals disperse locally. Local dispersal of pollen and seeds facilitates inbreeding because pollen pools are likely to contain relatives. Self-incompatibility promotes outbreeding because relatives are likely to carry incompatible alleles. Therefore, populations can experience an antagonism between these forces. In this study, a novel computational model is used to explore the effects of this antagonism on gene flow, allelic diversity, neighbourhood sizes, and identity by descent. I confirm that this antagonism is sensitive to dispersal levels and linkage. However, the results suggest that there is little to no difference between the effects of gametophytic and sporophytic self-incompatibility systems (GSI and SSI) on unlinked loci. More importantly, both GSI and SSI affect unlinked loci in a manner similar to obligate outcrossing without mating types. This suggests that the primary evolutionary impact of self-incompatibility systems may be to prevent selfing, and prevention of biparental inbreeding might be a beneficial side-effect.  相似文献
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号