Persistence in a Saltmarsh Insect Community: Experiments with Local Extinctions, Dispersal, and Colonization

盐沼昆虫群落的持久性：局部灭绝、扩散和定殖实验

• 批准号: 9007429
• 负责人: Donald Strong
• 金额: $ 18.93万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-07-01 至 1991-07-01
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9007429&HistoricalAwards=false
• 关键词: Persistence; Saltmarsh; Insect; Community; Experiments

Local populations of the gall midge Asphondylia borrichiae Rossi and Strong apparently become extinct and are re-established by immigrants frequently, as indicated by our work with this new species of fly. Patches of the sole host plant, sea oxeye daisy (Borrichia frutescens) are all small and discrete. There are no vast "mainland" patches, and gall-midge populations contributing colonists to locally extinct populations are about the size of those that have become extinct. The investigator posit that this is a true "metapopulation" system (sensu Levins 1970), in which persistence is due to recolonization after local extintion among roughly even-sized patches. Parasitoids are a major threat but are spotty in their effects. In excess of 95% parasitism occurs in some sea oxeye patches, while other patches have much lower rates. Patches with temporarily low parasitism rates are likely to provide immigrant to extinct local midge populations. Three sets of experiments will assess metapopulation dynamics. (1) Forced extinction of midges in natural sea Oxeye patches and (2) creation of new patches in salt marsh will indicate the role of natural immigration in persistence. (3) New patches of sea oxeye daisy, created in bayou areas far inland from natural midge population, will permit comparisons of persistence, with and without parasitoids, in the absemce of midge immigration. This investigation will yield critical information regarding scales of interactions important to many biological system //

当地的瘿蚊（Asphondylia borrichiae Rossi和Strong）种群显然已经灭绝，并经常被移民重新建立起来，正如我们对这种新种苍蝇的研究所表明的那样。唯一的寄主植物，海牛眼雏菊（Borrichia frutescens）都是小而分散的。没有巨大的“大陆”斑块，为当地灭绝种群贡献殖民者的瘿蚊种群的规模与那些已经灭绝的种群大致相同。研究者认为这是一个真正的“元种群”系统（sensu Levins 1970），其中持久性是由于在大致均匀的斑块中局部灭绝后的重新定居。拟寄生物是主要威胁，但其影响参差不齐。有些海牛眼斑区寄生率超过95%，而其他斑区则低得多。寄生率暂时较低的斑块可能为灭绝的当地蠓种群提供移民。三组实验将评估超种群动态。(1)自然海牛眼斑蚊被迫灭绝，(2)盐沼新斑蚊的形成表明自然迁移在持久性中的作用。(3)在远离天然蠓群的内陆河口地区种植的新海牛眼雏菊，可以比较在没有蠓迁徙的情况下，有和没有寄生性昆虫的持久性。这项研究将产生对许多生物系统至关重要的相互作用尺度的关键信息