Experimental and theoretical study on the relationship between genetic diversity and system stability

本项目的主要目的是从实验和理论上研究遗传多样性与系统稳定性之间的关系。这是基于我们之前的发现，在由赤小豆象甲及其幼虫寄生黄蜂组成的实验捕食-捕食系统中，小豆象甲杂交品系与寄生黄蜂共存的时间明显长于任何一个纯品系。基于这一发现，我们集中精力总结了遗传多样性对系统稳定性的重要性，并找到了促进这种关系的机制。在我们的实验研究中，我们使用了两种菜豆象甲和两种钝顶刺蛾，以及三种寄生黄蜂：H.prosopidis，Anisopteromalus calandrae和Dinarmus basalis。黄曲霉在豆象属…中具有独特的特征更多的卵，因为它产卵而不是将卵附着在豆子表面。这种特殊的产卵方法需要孵化的幼虫找到豆子并借用入口。由于先驱者的初始死亡率较高，孵化出的幼虫最好是跟随者。因此，父母必须决定两种幼虫的最佳比例，才能达到最高的适合度。同时，后代(卵)必须有两种类型的最佳比例才能存活。因此，可能存在亲子冲突。通过对菜豆幼虫行为的仔细观察，我们发现，争夺型竞争品系的幼虫在菜豆中构壁，限制了与其他幼虫的直接接触，最终允许多只幼虫以成虫的身份出现；而竞赛型竞争品系的幼虫没有构壁，最终在菜豆中相互接触，只有一只幼虫可以作为成虫羽化。这表明，即使在一个品系中，竞争策略也可以是灵活的，可以根据它们赖以生存的豆子的质量(特别是大小)进行选择。较少

The main purpose of the present project is to investigate experimentally and theoretically the relationship between genetic diversity and system stability. This is based on our previous findings that, in the experimental prey-predator system consisting of the azuki bean weevil (Callosobruchus chinensis) and its larval parasitic wasp (Heterospilus prosopidis), the system with the hybrid strain of the azuki bean weevil could coexist with parasitic wasps significantly longer than the system with either of the pure strains. Based on this finding, we concentrated our effort to generalize the importance of the genetic diversity on the system stability, and also to find the mechanisms promoting such relationships.In our experimental study, we employed two species of bean weevils, Callosobruchus maculates and Acanthoscelides obtectus, and three species of parasitic wasps, H.prosopidis, Anisopteromalus calandrae, and Dinarmus basalis. A.obtectus has a unique characteristics among the bean weevi … More ls, in that it lays eggs not attaching its eggs on the surface of the beans. This particular oviposition method necessitates the hatched larvae to find beans and borrow the entrance. There are two kinds of larvae, one (which we call pioneer) which actively borrow the entrance hole on the bean, and the other (which we call follower) which use the entrance hole made by pioneer. As the initial mortality of the pioneer is rather high, it is better for the hatched larvae to be a follower. Thus, the parent must decide the optimal proportion of the two types of larvae for her highest fitness. At the same time, offspring (eggs) must have some optimal proportion of the two types for their survival. Thus, there are possible parent-offspring conflicts. We carried out the experimental and theoretical studies for their optimal solution.In one strain of C.maculatus, we observed two strategies of larval competition (contest and scramble) in different lines. By careful observation of the larval behavior in the beans, we found that the larvae of the line with scramble type competition construct the wall in the bean, which restricted the direct contact with other larvae and eventually allowed multiple larvae emerge as adults, whereas, the larvae of the contest type competition constructed no wall, and eventually contacted each other in the bean, and only one larva could emerge as adult. This shows that even within one strain of C.maculatus, the competition strategy can be flexible, and can be selected for by the quality (especially size) of beans on which they feed. Less