Burrowing in the bark or in the sapwood: a dynamic game between a mother and her offspring

作者：Uchinomiya Kouki; Iwasa Yoh^*

来源：Evolutionary Ecology Research, 2011, 13(6): 607-623.

• ambrosia beetle
• bark beetle
• dynamic game
• evolutionarily stable strategy
• wood-burrowing beetles

Question: Why do some wood-burrowing insects (e.g. bark beetles) live in and feed on inner bark only, whereas others (e.g. ambrosia beetles) live in and feed on sapwood only?
Mathematical model: An ovipositing female burrows into both the inner bark and the sapwood. Each of her offspring chooses which microhabitat to stay in and feed on.
Key assumptions: Larvae choose their microhabitat depending on their mother's burrowing behaviour, which makes the model a dynamic game between the mother and her larvae. Larvae within each microhabitat compete with each other. Alternative assumption: If their mother does not burrow in order to oviposit, either no larvae survive or some do.
Results: If no larvae survive without maternal burrowing, two evolutionarily stable strategies (ESS) exist. Either both adults and larvae use only the inner bark, or else they use only the sapwood. Which ESS evolves depends on the relative suitability of the two microhabitats, the cost of burrowing by adults, and the intensity of competition. However, if some larvae survive in the absence of maternal burrowing, the ESS can be a mixture of both microhabitats.
Conclusion: Wood burrowing insects are likely to evolve to use either the inner bark only or the sapwood only. If larvae can grow despite the absence of maternal burrowing, they may evolve to use both microhabitats.

• 出版日期2011-9