Breeder-helper-interactions in the pied kingfisher reflect the costs and benefits of cooperative breeding
Breeder-helper-interactions in the pied kingfisher reflect the costs and benefits of cooperative breeding
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花斑翠鸟的饲养者与助手之间的相互作用反映了合作繁殖的成本和收益
DOI：
10.1163/156853986x00522
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
H. Reyer
中科院分区：
文献类型：
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作者：
H. Reyer
在大多数社会物种中，群体成员之间不仅存在合作，也存在冲突。尽管各种理论模型都明确了冲突与合作的条件、程度和方向，但很少有实证数据来检验它们的预测。本文报道了针对斑翠鸟（Ceryle rudis）的此类测试，这是一种与两种类型的雄性助鸟合作繁殖的鸟类：主要（=相关）和次要（=不相关）。在维多利亚湖（肯尼亚）的一个繁殖群中，对这些鸟类进行了以下方面的研究：（a）雏鸟孵化前后饲养者和助手之间的攻击性和非攻击性相互作用； (b) 猎物从辅助者转移到繁殖者的频率和影响； (c) 带给雌性和雏鸟的猎物的大小和类型。该研究的六个主要结果及其解释如下： 结果 1. 雄性饲养者攻击次要雄性帮手的频率高于主要雄性帮手（表 1）。解释：由于雄性过剩较多，所有帮手也是潜在的竞争对手，与雄性饲养者争夺与稀缺雌性的性接触机会。然而，与主要帮手相比，次要帮手对雄性饲养者的健康带来更高的成本和更低的收益。这是因为它们提供的帮助较少，似乎在帮助当年使卵子受精的能力更强，更有可能在随后的几年中取代饲养者，并且与饲养者的关系比主要帮助者更远。结果 2. 主要帮手对待次要帮手的方式与雄性饲养员相同（表 1）。说明：主要帮手与他们抚养的孩子密切相关。因此，任何影响饲养员的次要帮手竞争都会降低主要帮手的包容性适应性。结果 3. 雌性饲养员比雄性饲养员和一级帮手更容易容忍二级帮手（表 1）。解释：女性不会承担男性与男性竞争的成本；事实上，它们甚至从中受益，因为（a）有额外的雄性（=二级帮手），它们在产卵过程中比没有它们时获得更好的食物供应，（b）二级帮手比雄性饲养员和主要帮手更能降低雌性对雏鸟的食物贡献。结果 4. 通过提供鱼，次要帮手可以降低它们受到繁殖对和任何主要帮手攻击的可能性（表 I）。解释：帮工的食物转移被解释为被接纳为团体成员的“付款”。接收鱼可以提高饲养者和初级帮手的能量预算以及幼鸟羽翼丰满的机会，从而降低耐受帮手的成本/效益比。对于雌性来说，这种情况在卵子形成期间就已经存在，对于雄性来说，只有在孵化后，盗配的风险较低，并且辅助者可以提高幼体的生存率时。结果 5. 雏鸟孵化后，主要帮手给雏鸟（通常是其同胞）携带的食物多于雌鸟，而次要帮手给雌鸟携带的食物多于不相关的雏鸟（表 2 和图 1）。解释：初级帮手主要通过养育近亲来提高包容性适应性，次要帮手主要通过提高寻找伴侣和繁衍后代的机会。结果 6. 在有两个或三个辅助助手的群体中，每个助手往往比只有一个助手的群体为雏鸟提供更多的食物（图 2）。解释：拥有两个或三个二级帮手的群体与只有一个帮手的群体的不同之处在于（a）繁殖者从每个帮手那里获得的平均收益，以及（b）雄性与雄性对雌性作为未来伴侣的竞争程度。助鸟对较大群体中的雏鸟的较高食物贡献被解释为（a）为获得容忍而付出的更高代价，以及（b）为向雌性传达其父母品质的信号而付出的努力。结论是，所有行为互动和食物贡献都密切反映了给予和接受帮助的成本和收益，这随着饲养者的性别、群体成员之间的相关性以及繁殖周期的时期而变化。
In most social species there is not only cooperation but also conflict between group members. Although various theoretical models have specified the conditions for, and the extent and direction of conflict and cooperation, there are few empirical data to test their predictions. This paper reports such a test for the pied kingfisher (Ceryle rudis), a cooperatively breeding bird species with two types of male helpers: primary (= related) and secondary (= unrelated). In a breeding colony at Lake Victoria (Kenya), the birds were studied with regard to: (a) aggressive and non-aggressive interactions between breeders and helpers before and after chicks hatched; (b) frequency and effect of prey transfer from helpers to breeders; and (c) sizes and types of prey brought to females and nestlings. The six major results of the study and their explanations are as follows: Result 1. Male breeders attack secondary male helpers more often than primary helpers (Table 1). Explanation: Because of a high male surplus, all helpers are also potential rivals, competing with male breeders for sexual access to the scarce females. Secondary helpers, however, impose higher costs and lower benefits on the male breeders' fitness than do primary helpers. This is because they provide less help, seem to be more capable of fertilizing eggs in the year of help, are more likely to displace breeders in subsequent years, and are more distantly related to breeders than are primary helpers. Result 2. Primary helpers treat secondary helpers in the same way as male breeders do (Table 1). Explanation: Primary helpers are closely related to the young they raise. Therefore, any competition from secondary helpers that affects the breeder will decrease the primary helpers inclusive fitness. Result 3. Female breeders tolerate secondary helpers more readily than do male breeders and primary helpers (Table 1). Explanation: Females do not incur the costs of male-male competition; indeed they even benefit from it, because (a) with additional males (= secondary helpers) they get a better food supply during egg formation than without them, and (b) secondary helpers lower the females' food contributions to nestlings more than those of male breeders and primary helpers. Result 4. By offering fish, secondary helpers reduce the probability that they will be attacked by the breeding pair and any primary helpers (Table I). Explanation: The helpers' food transfer is interpreted as a "payment" for being accepted as a group member. Receiving fish improves the breeders' and primary helpers' energy-budgets and their chances of fledging young and thus reduces the cost/benefit ratio of tolerating helpers. For females this holds already during egg formation, for males only after hatching, when the risk of kleptogamy is low, and when helpers can improve survival of the young. Result 5. After the young have hatched, primary helpers carry more food to nestlings (= usually their sibs) than to females, whereas secondary helpers carry more to females than to unrelated nestlings (Table 2 and Fig. 1). Explanation: Primary helpers increase their inclusive fitness mainly through raising close kin, secondary helpers mainly through improving their chances of finding a mate and reproducing themselves. Result 6. In groups with two or three secondary helpers, each helper tends to provide the nestlings with more food than in groups with only one helper (Fig. 2). Explanation: Groups with two or three secondary helpers differ from groups with only one helper (a) in the breeders' average gain from each helper, and (b) in the extent of male-male competition for females as prospective mates. The helpers' higher food contribution to nestlings in bigger groups is interpreted (a) as a higher payment for being tolerated, and (b) as increased effort to signal their parental qualities to the females. It is concluded that all behavioral interactions and food contributions closely reflect the costs and benefits of giving and receiving help, which vary with the sex of the breeder, the relatedness between the group members, and the period of the reproductive cycle.