State-dependent cooperation in burying beetles: parents adjust their contribution towards care based on both their own and their partner’s size

Handicapping experiments on species with biparental care show that a focal parent increases its contribution when its partner is handicapped. Such results are interpreted as evidence for negotiation, whereby each parent adjusts its amount of care to that of its partner. However, it is currently unclear whether the focal parent responds to a change in its handicapped partner's behaviour or state. To address this gap, we conducted an experiment on the burying beetle Nicrophorus vespilloides where we first experimentally generated different-sized male and female parents by varying the duration of larval development. We then used a 2×2 factorial design in which a small or large male was paired with a small or large female. Small females provided less direct care (food provisioning and interactions with larvae) than large females, and males and females provided less direct care when paired with a small partner. Thus, the focal parent adjusted its contribution towards care based on both its o...

针对具有双亲抚育（biparental care）行为的物种开展的障碍实验表明，当配偶被施加障碍时，焦点亲代（focal parent）的抚育投入会增加。这类结果被解读为协商机制（negotiation）的证据——即亲代双方会根据配偶的抚育投入量调整自身的投入。然而，目前尚不清楚焦点亲代是对被施加障碍的配偶的行为变化做出反应，还是对其状态变化做出反应。为填补这一空白，我们以埋葬甲虫Nicrophorus vespilloides为研究对象开展了一项实验：首先通过改变幼虫发育时长，实验性地培育出体型大小各异的雌雄亲代。随后，我们采用2×2析因设计（factorial design），将体型小或大的雄性分别与体型小或大的雌性配对。体型小的雌性提供的直接抚育（direct care，包括食物供给及与幼虫的互动）少于体型大的雌性；且无论雌雄，与体型小的配偶配对时，其提供的直接抚育均会减少。因此，焦点亲代的抚育投入调整基于其自身的……