Influence of age on chiasma number in male Locusta migratoria.

The influence of age on chiasma formation in Locusta migratoria has been studied both in wild-type and irradiated males. Samples were obtained on the one hand from different individuals and on the other hand from the same individuals at different ages through repeated biopsies. It was observed that mean chiasmata per cell decreased in ageing animals. Chi-squared tests and correlation coefficients showed that the decrease of chiasmata with age is progressive but not continuous. Intermediate values coincide with the first mating. It seems that older individuals tend to transmit their genetic combinations unaltered, increasing the probability of transmitting gene combinations of adaptive value.