ABSENCE OF STRONG HETEROSIS FOR LIFE-SPAN AND OTHER LIFE-HISTORY TRAITS IN CAENORHABDITIS-ELEGANS

We have examined crosses between wild-type strains of Caenorhabditis e legans for heterosis effects on life span and other life history trait s. Hermaphrodites of all wild strains had similar life expectancies bu t males of two strains had shorter life spans than hermaphrodites whil e males of two other strains lived longer than hermaphrodites. F1 herm aphrodite progeny showed no heterosis while some heterosis for longer life span was detected in F1 males. F1 hybrids of crosses between two widely studied wild-type strains, N2 (var. Bristol) and Berg BO (var. Bergerac), were examined for rate of development, hermaphrodite fertil ity, and behavior; there was no heterosis for these life history trait s. Both controlled variation of temperature and uncontrolled environme ntal variation affected the length of life of all genotypes. Significa nt G X E effects on life span were observed in comparisons of N2 and B erg BO hermaphrodites, or N2 hermaphrodites and males, or N2 and a Ts mutant strain (DH26). Nevertheless, within an experiment, environmenta l variation was minimal and life spans were quite replicable.