EVIDENCE OF HYBRID VIGOR IN SUBSPECIFIC HYBRIDS OF THE SADDLE-BACK TAMARIN (SAGUINUS-FUSCICOLLIS)

The effect of hybridization on infant survival was investigated in sub specific crosses of the saddle-back tamarin (Saguinus fuscicollis) at the Oak Ridge Associated Universities (ORAU) Marmoset Research Center (Oak Ridge, TN). Cox Proportional Hazards Regression was used to compa re infant survival between 1) pure subspecies, 2) F1, F2, and backcros sed hybrids, and 3) hybrids and their parental subspecies. Also, effec ts of management changes, sex, and litter size on infant survival were investigated. There were no significant differences in infant surviva l between the pure subspecies. Also, degree of hybridization (Pi, F2, or backcross) did not have a significant effect on infant survival. Pr ogeny of hybrid crosses between S. f. lagonotus and S. f. illigeri was found to have significantly (P < 0.05) higher infant survival than bo th of their parental subspecies. Individuals born after diet and manag ement changes in the colony had significantly (P < 0.05) higher surviv al than those born before. There were no significant sex differences i n infant survival. Individuals born into triplet litters had significa ntly (P < 0.05) lower survival than those born into twin litters. Thes e results show heterosis (hybrid vigor) for infant survival in one sub specific S. fuscicollis cross (S. f. lagonotus x S. f. illigeri). The results suggest genetic divergence between the subspecies populations and possible reproductive isolation in the wild. (C) 1994 Wiley-Liss, Inc,