Asymptotic weight and maturing rate in mice selected for body conformation

Growth patterns of four lines of mice selected for body conformation were a nalyzed with the logistic function, in order to provide baseline informatio n about the relationship between asymptotic weight and maturing rate of bod y weight. Two lines were divergently selected favoring the phenotypic corre lation between body weight and tail length (agonistic selection: CBi+, high body weight and long tail; CBi-, low body weight and short tail), whereas the other two lines were generated by a disruptive selection performed agai nst the correlation between the aforementioned traits (antagonistic selecti on: CBi/C, high body weight and short tail; CBi/L, low body weight and long tail). The logistic parameters A (asymptotic weight) and k (maturing rate) behaved in CBi/C and CBi- mice and in CBi+ females as expected in terms of the negative genetic relationship between mature size and earliness of mat uring. An altered growth pattern was found in CBi/L mice and in CBi+ males, because in the former genotype, selected far low body weight, the time tak en to mature increased, whereas in the latter, selected for high body weigh t, there was a non-significant increase in the same trait. In accordance wi th the selective criterion, different sources of genetic variation for body weight could be exploited: one inversely associated with earliness of matu ring (agonistic selection), and the other independent of maturing rate (ant agonistic selection), showing that genetic variation of Ais partly independ ent of k.