REU: Energetics of Competitive Behavior

在许多生物体中，兄弟姐妹会积极争夺有限的父母资源，这往往会给一些幼崽带来致命的结果。有时，这种竞争会因公开的攻击性和统治等级的建立而加剧。牺牲近亲的自我促进行为的演变被认为受到两个主要因素的制约：(1)幸存者和受害者之间的遗传联系；(2)与激烈的竞争性乞讨和/或打斗相关的能量成本。在这项研究中，这些能量成本将在牛鹭(BuBulcus Ibis)的三个雏鸟中进行测量，牛鹭是一种丰富的集群鸟类，采用杀虫药物，使用“双标记水”(一种稳定同位素的混合物)。在两天的时间里，注射少量这种化合物的雏鸟将在所有清醒时间内受到密切监测，之后对微量血液样本的分析将揭示总能量消耗。这种方法将应用于不同活动水平的雏鸟，从而可以确定每个重点活动(乞讨和打架)的单位成本。这项工作将检验和修改目前的家庭内部冲突理论，因为它直接涉及乞讨和打架代价高昂这一前提。它还将提供有关父母照顾效率的信息，通过显示父母提供的食物能量中有多少用于生长，而不是自我保护。在更实际的层面上，这一知识和方法本身很可能适用于各种稀有和濒危物种(例如，尖叫鹤、各种鹰、褐鹈鹕)，它们的雏鸟竞争致命。

In many organisms, siblings compete actively for limited parental resources, often with fatal results for some brood members. Sometimes this rivalry is accentuated by overt aggression and the establishment of dominance hierarchies. The evolution of self-promoting behavior that sacrifices close kin is believed to be constrained by two main factors: (i) the genetic relatedness between survivor and victim and (ii) the energetic costs associated with vigorous competitive begging and/or fighting. In this study, these energetic costs will be measured in three-chick broods of cattle egrets (Bubulcus ibis), an abundant colonial bird that practices siblicide, using "doubly labelled water" (a mixture of stable isotopes). The behavior of chicks injected with small amounts of this compound will be monitored closely during all waking hours over a two-day period, after which analysis of a tiny blood sample will reveal the total energy spent. This method will be applied to chicks of various activity levels, so that the unit costs of each focal activity (begging and fighting) can be determined. This exercise will allow testing and modification of current intra-family conflict theory, as it directly addresses the premise that begging and fighting are expensive. It will also provide information about the efficiency of parental care, by showing how much of parentally supplied food energy is used for growth, as opposed to self-protection. On a more practical level, this knowledge, and the approach itself, is likely to be applicable to various rare and endangered species (e.g., whooping cranes, various eagles, brown pelicans) whose nestlings compete fatally.