Toward a Unifying Theory of Social Evolution: Testing Competing Models of Reproductive Skew in an Avian Cooperative Breeder

走向社会进化的统一理论：在鸟类合作的家庭中测试繁殖倾斜的竞争模式。施普芬·T·恩普罗杰摘要(外行术语)家庭(定义为遗传亲属的多代集合)是所有形式的社会组织中最不被理解的之一。然而，因为它是我们人类的基本社会组织，它可以说是我们理解的最重要的。只有大约3%的鸟类和哺乳动物生活在以家庭为基础的社会中，其中只有少数得到了详细的研究。家庭有不同的大小和形式。鸟类和哺乳动物中最常见的形式是核心家庭，当成年后与父母在一起时形成的核心家庭，但只有父母才能繁殖。大多数所谓的“合作饲养者”都属于这一类，成年的儿子和女儿仍然在父母的巢或窝里当帮手。不太常见，但更令人感兴趣的是大家庭，当许多家庭成员分享生殖时形成的大家庭。当一个家庭中有多对配对时，结果不仅是父母和后代的混合，而且还有祖父母、叔叔阿姨、侄女和侄子、堂兄弟姐妹以及无关的姻亲的混合。直到最近，我们人类主要生活在由这样的大家庭单位组成的群体中。大家庭和核心家庭之间的区别是共享和独占繁殖的区别。越来越多的进化模型，统称为生殖扭曲理论，试图解释自然界中发现的生殖抑制的可变性。偏斜模型结合了少量的因素(两个生态的，一个遗传的和一个社会的)来预测1)稳定的家庭群体何时形成，2)它们的稳定规模，以及3)家庭成员如何分享生殖。生殖偏斜模型引起了行为生态学家和进化生物学家的极大兴趣，因为它将动物社会的许多主要特征与它们的生态、遗传和社会基础联系在一起。由于这种广泛性，一些工作人员认为，歪曲理论可能会为观察大部分社会进化提供一个统一的框架。然而，该理论的发展速度远远超过了用该领域中的真实动物对其假设和预测进行测试的速度。迫切需要对生活在以家庭为基础的社会中的鸟类和哺乳动物的扭曲理论进行详细的观察和实验研究。拟议的研究将提供这样的测试。被研究的物种是灰帽交织鸟(Pseudonigrita Arnaudi)，是东非哨刺稀树草原上的一种常见居民。之所以选择这个物种，是因为它既生活在大家庭单位中，也生活在核心家庭单位中，关于它的行为和生态的背景知识已经广为人知，而且它拥有许多特征，使得收集数据和进行实验变得容易。已经捕获了一个超过50个家庭单位的研究种群，并对这些鸟进行了单独的标记。已经开发了分子标记(微卫星基因座)，它将能够从基因上确定家庭结构(例如，谁是谁的父亲或阿姨)。该研究项目将帮助培训众多肯尼亚专业人员掌握现代行为研究方法。它还将结合几名高级研究人员的人才，他们的专长范围从行为的实地研究，到社会组织的分子研究，再到社会进化的理论模型。因此，它构成了对最近的倾斜模型对复杂脊椎动物社会适用性的首批综合测试之一。结果将增强我们对1)有利于家庭群体进化的因素的理解，2)大家庭在进化时发展的原因，以及3)家庭成员在彼此之间的合作和竞争互动中使用的行为(所谓的家庭动力学)。反过来，这也应该为我们提供对有利于我们自己物种中大家族群体的进化和维持的条件的洞察。

TOWARD A UNIFYING THEORY OF SOCIAL EVOLUTION: TESTING COMPETING MODELS OF REPRODUCTIVE SKEW IN AN AVIAN COOPERATIVE BREEDER.STEPHEN T. EMLENPROJECT SUMMARY (IN LAY TERMS)The family (defined as a multi-generation assemblage of genetic relatives) is among the least understood of all forms of social organization. Yet, because it is the basic social organization of our own species, it is arguably the most important for us to understand. Only about 3% of birds and mammals live in family-based societies, and only a few of these have been studied in detail.Families come in various sizes and forms. The most common form in both birds and mammals is the nuclear family, formed when grown young remain with their parents, but only the parents reproduce. Most so-called 'cooperative breeders' fit this category, with grown sons and daughters remaining as helpers at the nest or den of their parents. Less common, but of greater interest, is the extended family, formed when reproduction is shared among many family members. When multiple pairs within a single family breed, the result is a mixture not only of parents and offspring, but also of grandparents, uncles and aunts, nieces and nephews, and cousins as well as unrelated in-laws. Until very recently, we humans lived predominantly in groups comprised of such extended family units. The difference between extended and nuclear families is one of shared versus monopolized breeding. A rapidly growing number of evolutionary models, known collectively as reproductive skew theory, attempt to explain the variability of reproductive suppression found in nature. Skew models incorporate a small number of factors (two ecological, one genetic, and one social) to predict 1) when stable family groups will form, 2) what their stable size will be, and 3) how reproduction will be shared among family members.Reproductive skew they is generating considerable interest among behavioral ecologists and evolutionary biologists because it links many major features of animal societies to their ecological, genetic, and social underpinnings. Because of this breadth, some workers believe that skew theory may provide a unifying framework for viewing much of social evolution. However, the development of the theory has far outpaced the testing of its assumptions and predictions with real animals in the field. There is an urgent need for detailed observational and experimental studies of skew theory on birds and mammals that live in family-based societies.The proposed research will provide such a test. The study species is the Grey capped social weaver (Pseudonigrita arnaudi), a common inhabitant of the whistling thorn savanna of East Africa. This species was chosen because it lives in both extended and nuclear family units, background knowledge of its behavior and ecology is already well-known, and it possesses many features that make it logistically easy to collect data and perform experiments. A study population of over 50 family units has been captured and the birds individually marked. Molecular markers (microsatellite loci) have been developed that will allow genetic determination of family structures (e.g. who is the father, or aunt, of whom). The research program will help to train numerous Kenyan professionals in modern methods of behavioral research. It will also combine the talents of several senior investigators whose expertise ranges from field studies of behavior, to molecular studies of social organization, to theoretical modeling of social evolution. As such, it constitutes one of the first integrated tests of the applicability of recent skew models to a complex vertebrate society.The results should enhance our understanding of 1) the factors that favor the evolution of family groups, 2) the reasons why extended families develop when they do, and 3) the behaviors that family members use in their cooperative and competitive interactions with one another (so-called 'family dynamics'). This, in turn, should provide insights into the conditions that favored the evolution and maintenance of extended family groupings in our own species as well.