Effects of resource competition and apparent competition on community structure and distributions of drosophilids

资源竞争和表观竞争对果蝇群落结构和分布的影响

基本信息

批准号：
17570010
负责人：
KIMURA Masahito
金额：
$ 2.39万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

Competitive interactions between drosophilid species are investigated to understand how drosophilid communities are structured and how the boundary of their distributions, especially at lower latitudes are determined. There are two types of competitive interactions, resource competition and apparent competition mediated by organisms of higher trophic level, such as predators. By laboratory experiments on resource competition, it was suggested that intraspecific competition was rather strong in drosophilid species, but interspecific competition was not so strong. The results of field studies did not contradict with this result. Thus, the effects of resource competition on community structure or distribution seem to be weak. On the other hand, cold-tolerant species are expected to be vulnerable to predators or parasitoids, since their locomotor activity is reduced and their developmental period was prolonged, and therefore they may be excluded from warmer regions due to apparent competition with cold-susceptible species. However, little information is available for apparent competition of drosophilids. Then, the species composition, distribution and host association was studied for parasitoids that are assumed to mediate apparent competition. As a result, all parasitoids were able to parasitize a number of host species. Thus, they could mediate interactions between host drosophilid species. In temperate areas, however, the rate of parasitism was not high and there were a period free from parasitism, suggesting that apparent competition was weak. However, there is a possibility that apparent competition is rather severe in subtropical and tropical areas. Further study is needed on this topic.

研究果蝇物种之间的竞争性相互作用，以了解果蝇群落的结构以及它们的分布边界（特别是在低纬度地区）是如何确定的。有两种类型的竞争相互作用：资源竞争和由较高营养级生物（例如捕食者）介导的表观竞争。通过实验室资源竞争实验表明，果蝇种内竞争相当强烈，但种间竞争不那么强烈。实地研究的结果与这一结果并不矛盾。因此，资源竞争对群落结构或分布的影响似乎很弱。另一方面，耐寒物种预计容易受到捕食者或寄生蜂的攻击，因为它们的运动活动减少，发育周期延长，因此它们可能会因与易冷物种的明显竞争而被排除在温暖地区之外。然而，关于果蝇明显竞争的信息很少。然后，研究了寄生蜂的物种组成、分布和寄主关联，假定它们介导了明显的竞争。结果，所有寄生蜂都能够寄生许多宿主物种。因此，它们可以介导宿主果蝇物种之间的相互作用。但在温带地区，寄生率不高，并且有一段时间没有寄生，表明明显的竞争较弱。然而，亚热带和热带地区的明显竞争可能相当激烈。该主题需要进一步研究。