Abstract # 881 Event # 203:

Scheduled for Saturday, August 20, 2005 08:00 AM-08:15 AM: Session 15 (Parliament Room) Oral Presentation

Cooperative Breeding and Genetic Chimerism in Callitrichids

C. N. Ross1, G. Orti1 and J. A. French2
1University of Nebraska, 345 Manter Hall, Department of Biology, Lincoln, NE 68588-0118, USA, 2University of Nebraska - Omaha
     Kin selection theory proposes that selection should favor individuals who care for closely related kin because they gain indirect fitness benefits through the successful reproduction of relatives. Marmosets and tamarins are cooperative breeders that produce fraternal twins whose placentas fuse during embryonic development allowing genetic exchange via blood flow between the twins. This genetic exchange causes infants to be chimeras, having tissues made up of their own DNA as well as the DNA of their twin. For this study we used seven microsatellite markers to assess the extent and distribution of genetic exchange in Callithrix kuhlii between forty sets of twins with known parentage. Tissues derived from blood products have the highest rate of chimerism (blood 58.8%, liver 40%, and spleen 47.4%). However, all tissues sampled have been found to be chimeric: heart 12.5%, hair 37.5%, brain 10.5%, and gonad 18.7%. The use of microsatellites allows us to track alleles through generations, in three families we found that parents are transmitting their chimeric alleles as well as their own alleles to their offspring. Using this data we will now be able to estimate degrees of relatedness between family members, and model predicted behavior of group members. The study of this unique system provides insights into mechanisms affecting alloparental care and kin selection, and may alter our views of the evolution of social behavior.