Demographic Change and Reproductive Skew in Cooperative Breeding Primates (resubmit)

虽然与其他社会制度相比很少见，但合作繁殖物种提供了独特的机会来检验解释以亲属为基础的社会中合作和竞争的演变的假说。早期的研究集中在异位护理的适应性意义上。具体地说，为什么成熟的成年人留在他们的出生群体中帮助抚养后代，而不是他们自己的后代？对于不同种类的鸟类和少数哺乳动物，在解决最初的问题--为什么帮助者会提供帮助--方面取得了实质性进展。通过呆在家里，异种人通常会增加他们找到繁殖机会的机会，并在间接健康中获得收益。对圈养的卡利氏灵长类动物(绒猴、罗望子和狮子罗望子)的早期研究表明，社会和基因一夫一妻制是该家庭的常态，但最近来自野外和圈养环境的报告表明，卡利特里德的社会组织具有高度的灵活性，无论是在种群内还是在不同的分类群中。这种可变性为检验有关生殖扭曲和延迟扩散基础的假说提供了肥沃的土壤。Dietz、Baker和他的同事们提议对巴西Poco das Antas保护区的金狮金丝猴进行为期3年的行为和人口统计学研究。这项历时17年的研究在解决人口层面和范围问题方面是独一无二的，维持了一套完整的数据库，包括行为、人口学、亲属关系、形态、生殖、空间利用、群体动态、食物习惯和血液、头发和粪便样本。在本研究的前13年中，狮子的领地占据了保护区内所有合适的栖息地，大多数种群都有几个帮手，种群的增长受到出生种群扩散过程中高死亡率的限制。在过去的三年里，一种新的捕食形式，即在洞穴中屠杀整个群体，导致在研究种群中生存的个体的社会、经验和人口背景发生了深刻的变化。人口密度、群体规模和帮助者数量减少，群体灭绝/重新定居的比率增加。实际上，这种捕食增加的脉冲导致了一次独特的自然实验。与捕食加剧之前的条件相比，Poco das Antas现在包含了更多的繁殖机会，为分散的个体提供了更多的繁殖机会，减少了填补这些空位的竞争，减少了照顾群体后代的异种。通过比较捕食增加前后的扩散和生殖共享的模式，以及通过将分子遗传学和内分泌技术与野外数据相结合，这些研究人员建议确定罗望子鱼是否正在评估出生群体外繁殖机会的可用性和质量，生态限制对扩散和生殖共享的影响程度，遗传亲缘关系对从属繁殖的影响，近亲交配和年龄对生殖倾斜的相对影响，以及蚂蚁控制从属繁殖的环境和机制。最后，这个由NSF赞助的项目的存在为管理保护区的巴西政府机构提供了资源、声望和激励，并成为培训巴西和美国所有专业水平的生物学家的平台。这项研究的结果构成了管理所有四个狮子罗望鱼分类群的科学基础，并被用来证明建立一个新的生物保护区是合理的，并为当地项目提供信息和执行，包括重新造林、种植森林走廊、保护教育、重新引入和转移。

Although rare relative to other social systems, cooperative breeding species present unique opportunities to examine hypotheses explaining the evolution of cooperation and competition in kin-based societies. Early studies focused on the adaptive significance of alloparental care. Specifically, why did mature adults remain in their natal groups helping to raise offspring not their own? For various species of birds and a few mammals, substantial progress has been made in addressing the original question of why helpers help. By staying at home, alloparents often improve their chances of finding a breeding opportunity and receive gains in indirect fitness. Early research on callitrichid primates (marmosets, tamarins and lion tamarins) in captivity suggested that social and genetic monogamy was the norm for the family but recent reports from the wild and in captive settings suggested that callitrichid social organization is highly flexible, both within populations and across taxa. This variability provides fertile ground for testing hypotheses concerning the basis of reproductive skew and delayed dispersal. Dietz, Baker and colleagues propose a 3-year continuation of behavioral and demographic research on golden lion tamarin monkeys in Poco das Antas Reserve, Brazil. This 17-year study is unique in terms of its ability to address questions at the population level and in its scope, maintaining an integrated set of databases including behavior, demography, kinship, morphology, reproduction, use of space, group dynamics, food habits and samples of blood, hair and feces. During the first 13 years of this research, lion tamarin territories occupied all suitable habitat in the reserve, most groups contained several helpers and population growth was limited by high mortality during dispersal from natal groups. In the past three years a novel form of predation, decimation of complete groups while in den sites, resulted in profound changes in the social, experiential and demographic context of individuals surviving in the study population. Population density, group size and number of helpers decreased, and the rate of group extinction/recolonization increased. In effect, this pulse of increased predation resulted in a unique natural experiment. Relative to conditions before increased predation, Poco das Antas now contains more breeding opportunities for dispersing individuals, less competition to fill those slots and fewer alloparents to care for group offspring.By comparing patterns of dispersal and reproductive sharing before and after increased predation, and by integrating molecular genetic and endocrine techniques with field data, these investigators propose to determine if tamarins are assessing the availability and quality of reproductive opportunities outside the natal group, the extent to which ecological constraints affect dispersal and reproductive sharing, the effects of genetic relatedness on subordinate breeding, the relative effects of inbreeding avoidance and age on reproductive skew, and the circumstances and mechanisms by which dominants control reproduction of subordinates. Finally, the presence of this NSF-sponsored project provides resources, prestige and incentive to the Brazilian government agency managing the reserve and serves as a platform for training Brazilian and American biologists at all professional levels. Results of this research form the scientific basis for management of all four taxa of lion tamarins and were used to justify the creation of a new biological reserve and to inform and implement local projects including reforestation, planting of forest corridors, conservation education, reintroduction and translocation.