Hawkesbury Institute for the Environment, Western Sydney University, Richmond, Australia.
Biological Sciences, Macquarie University, Sydney, Australia.
Nat Ecol Evol. 2018 Jun;2(6):1009-1018. doi: 10.1038/s41559-018-0533-3. Epub 2018 Apr 23.
The lifetime monogamy hypothesis claims that the evolution of permanently unmated worker castes always requires maximal full-sibling relatedness to be established first. The long-lived diploid ambrosia beetle Austroplatypus incompertus (Schedl) is known to be highly social, but whether it has lifetime sterile castes has remained unclear. Here we show that the gallery systems of this beetle inside the heartwood of live Eucalyptus trees are always inhabited by a single core family, consisting of a lifetime-inseminated mother, permanently unmated daughter workers, and immatures that are always full siblings to each other and their adult caretakers. Overall sex ratios are even. Males always disperse and only survive as stored sperm, but female offspring either disperse to mate and found their own colony or assume unmated worker roles, probably surviving for many years without any reproductive potential because tarsal loss precludes later dispersal. A well-supported Platypodinae phylogeny has allowed us to infer that parental monogamy evolved before a lifetime-unmated worker caste emerged, confirming the prediction that monogamy and full-sibling relatedness are necessary conditions for the evolution of such workers. The initially very challenging but ultimately long-term stable nesting habitat in live trees appears to have provided the crucial benefit/cost factor for maintaining selection for permanently sterile workers after strict monogamy and lifetime sperm storage had become established in this curculionid coleopteran lineage.
终生一夫一妻制假说声称，永久性未交配工蜂群体的进化总是需要首先建立最大的全同胞关系。已知长寿命的二倍体粉状粒肩天牛 Austroplatypus incompertus（Schedl）高度社会化，但它是否具有终生不育的蜂群尚不清楚。在这里，我们表明，这种甲虫在活桉树心材内的画廊系统中总是由一个核心家族居住，该家族由终生授精的母亲、永久性未交配的女儿工蜂以及彼此之间以及与成年保育员都是全同胞的幼虫组成。总体性别比例是平衡的。雄性总是分散并仅作为储存的精子存活，但雌性后代要么分散交配并建立自己的殖民地，要么承担未交配的工蜂角色，可能会多年没有任何生殖潜力，因为跗骨损失排除了以后的分散。一个得到很好支持的 Platypodinae 系统发育树使我们能够推断出，亲代一夫一妻制是在出现终生不育的工蜂群体之前进化而来的，这证实了这样的假设，即一夫一妻制和全同胞关系是进化出这种工蜂的必要条件。在活树中最初非常具有挑战性但最终长期稳定的筑巢栖息地似乎为在严格的一夫一妻制和终生精子储存已经在这个象鼻虫Coleopteran 谱系中建立之后，维持对永久性不育工蜂的选择提供了关键的收益/成本因素。
