Higashi M, Yamamura N, Abe T, Burns T P
Faculty of Science and Technology, Ryukoku University, Otsu, Japan.
Proc Biol Sci. 1991 Oct 22;246(1315):25-9. doi: 10.1098/rspb.1991.0120.
No general theory explains why a sterile worker caste is not found in all species of both Hymenoptera and Isoptera (Insecta). Recent empirical finding show that, in the termites (Isoptera), feeding outside the nest correlates well with the evolution of the sterile (true) worker caste from the non-sterile (false) worker caste. Here we explain the connection between food-nest separation and true worker evolution in termites, providing a general theory on the restricted distribution of the sterile worker caste in the Isoptera. A cost-benefit model suggests that there is a critical level of nest stability above which natural selection favours true workers over false workers, irrespective of genetical relatedness. Because food-nest separation tends to increase nest stability, this theoretical result implies that the less a termite species consumes its nest as food, the more likely is its nest stability to fall above the critical level and a true worker caste will evolve.
没有一个通用理论能够解释为什么在膜翅目和等翅目（昆虫纲）的所有物种中都没有发现不育工蚁阶层。最近的实证研究结果表明，在白蚁（等翅目）中，巢外觅食与不育（真正的）工蚁阶层从非不育（假的）工蚁阶层的进化密切相关。在此，我们解释了白蚁中食物与巢穴分离和真正工蚁进化之间的联系，为等翅目不育工蚁阶层分布受限提供了一个通用理论。一个成本效益模型表明，存在一个关键的巢穴稳定性水平，高于这个水平，无论基因相关性如何，自然选择都更青睐真正的工蚁而非假工蚁。由于食物与巢穴分离往往会增加巢穴稳定性，这一理论结果意味着，白蚁物种消耗其巢穴作为食物的程度越低，其巢穴稳定性就越有可能高于关键水平，真正的工蚁阶层就会进化。
