Mutational changes of quantitative morphological traits in the convict cichlid ( Cichlasoma nigrofasciatum Guenther) after irradiation of parental spermatogonia and oogonia with different doses of X-rays

Abstract

10 continuous and 6 discrete variables of body dimensions as well as 16 proportions calculated from them were determined in postirradiation F 1 convict cichlid fish ( Cichlasoma nigrofasciatum) which were derived from spermatogonia and oogonia both exposed to either 0 (controls), 250, 500, 750, 1000, or 2000 R of X-rays. While no interactions with sex or radiation dose were found, clear dosage effects and some sex effects occurred. The highest response for almost all quantitative traits examined as well as for variants of coloration or of vertebral aberrations appeared after 250 R to both parental germ cells. The lowest effectiveness was observed for almost all characters under investigation after 0 and 500 R. Accordingly, the largest difference between the 6 different treatment groups was found between 250 and 500 R, followed by 250 and 0, 250 and 1000, and 250 and 750 R to parental gonia. The present finding on the alterations of quantitative morphological traits completely corresponds to the changes of intraspecific aggressiveness as found for the same individual fish in a previous study thus confirming the complete congruence of the mutational response of quantitative morphological characters with that of behavioral traits to ionizing radiation.