Paternity, Cooperative Breeding, and Genetic Chimerism in Callitrichids

吉列尔莫·奥尔蒂、杰弗里·a·弗兰奇和科琳娜·罗斯是雀科猴的新品种，它们组成了大型的合作繁殖群体，其中许多个体照顾繁殖对的后代。为了解释这种基于帮助提供者的间接适合度利益的行为，有必要确定个体之间真正的遗传关系。这对狨猴来说并不容易，因为它们独特的生殖系统。狨猴产生异卵双胞胎，其胎盘在胚胎发育早期融合，通过双胞胎之间的血液流动导致基因交换。这种基因交换导致婴儿成为基因嵌合体，其组织中含有含有自己DNA的细胞和含有双胞胎DNA的细胞的混合物。人们对基因交换的程度和哪些组织受到影响知之甚少。这项拟议的研究将使用微卫星遗传标记来评估双胞胎在发育过程中基因交换的程度和分布。研究人员将使用从一个繁殖群体中保存下来的标本，从已知的两对库氏卡利思虫的雌雄配对中提取至少10种组织。进一步的研究将评估包含多个雄性的繁殖群体的遗传父权，以确定是否有可能多个雄性孕育一组双胞胎。由于个体间共享等位基因的增加，水平遗传交换的记录可能会极大地影响间接适合度的计算。对这一独特系统的研究将有助于深入了解影响异体亲代照料、亲缘识别和亲缘选择的机制，并可能改变目前对社会行为进化的看法。

Paternity, Cooperative Breeding, and Genetic Chimerism in CallitrichidsPI: Guillermo Orti, Jeffrey A. French and Corinna RossMarmosets are New World monkeys of the family Callitrichidae that form large cooperative breeding groups in which many individuals care for the offspring of the breeding pair. In order to explain this behavior based on indirect fitness benefits for the help providers, it is necessary to determine the true genetic relationship among individuals. This is not easy to do for marmosets because of their unique reproductive system. Marmosets produce fraternal twins, whose placentas fuse during early embryonic development, resulting in genetic exchange through the blood flowing between the twins. This genetic exchange causes the infants to be genetic chimeras, having tissues with mixtures of cells with their own DNA and cells with the DNA of their twin. Little is known about the extent of genetic exchange and what tissues are affected. The proposed study will use microsatellite genetic markers to assess the extent and distribution of genetic exchange between twins during development. At least ten types of tissues from twin sets of known female-male pairings of Callithrix kuhlii will be assayed, using specimens archived from a breeding colony. Further studies will assess genetic paternity in the breeding groups that contained multiple males, in order to determine whether it is possible that multiple males are siring a single set of twins. Documentation of horizontal genetic exchange may drastically affect calculations of indirect fitness due to an increase in shared alleles between individuals. The study of this unique system will provide insights into the mechanisms affecting alloparental care, kin recognition, and kin selection and may alter current views of the evolution of social behavior.