Abstract # 221:

Scheduled for Saturday, August 19, 2006 10:45 AM-11:00 AM: Session 21 (Regency East #3) Oral Presentation

Allocation of Infant Care and Genetic Chimerism in Callitrichids

C. N. Ross1, J. A. French2 and G. Orti1
1University of Nebraska-Lincoln, 324 Manter Hall, Department of Biology, Lincoln, NE 68588-0118, USA, 2University of Nebraska at Omaha
     Genetic chimerism, the mingling of two or more genomic lineages within an individual, is rare in mammals, but prevalent in callitrichid primates. Fraternal twins exchange cell lines via chorionic fusion during early development. Chimerism has previously been demonstrated to extend to somatic tissues and the germ line and this has important implications for the evolution of extensive paternal care typical of Callitrichid primates. In order to investigate whether chimerism alters care giving behavior of Callithrix kuhlii (Wied’s black-tufted ear marmoset), carrying effort of mothers and fathers for the first two weeks of life were assessed for infants determined via microsatellite genotyping to be epithelial chimeras (n = 10) and those determined to be non-chimeric (n = 20). Females carried chimeric infants significantly less than did females with non-chimeric infants (F1, 28=7.61, p=0.01), but fathers carried chimeric infants significantly more than fathers with non-chimeric infants (F1, 28=12.08, p=0.002). No significant differences in carrying time by mothers or fathers were found between groups due to parity (F1, 28=2.124, n.s.), or when grouped by family (F8, 28=1.865, n.s). This study is the first to demonstrate changes in social behavior associated with genetic chimerism and suggests that chorionic fusion and the resulting exchange of cell lines between twins may represent a unique maternal adaptation promoting paternal care.