English

Abstract

Data from the snail farm of the University of Calabar, Nigeria were collected and utilized to investigate the distribution and gene frequencies of egg shell colour of two ectotypes of Giant African Land Snails (Archachatina marginata var. saturalis), black skinned (BS) × black skinned mating group, and white skinned (WS) × white skinned mating group. The eggs collected were scored for the presence of yellow (Yp), light yellow (Lp) and milky white (Mp) egg shell colour. The egg shell colour distributions between the two ectotypes (BS × BS and WS × WS) were 46.50 vs. 3.77%, 42.68 vs. 48.11% and 10.83 vs. 48.11% for yellow, light yellow and milky white, respectively. In both ectotypes, the dominant gene for yellow, light yellow and milky white egg shell colour segregated at low frequencies (0.26 vs. 0.02, 0.24 vs. 0.31 and 0.06 vs. 0.31). The lowest value being yellow shell of the white skinned × white skinned mating group with frequency of 0.02, followed by milky white shell of the black skinned × black skinned mating group with frequency of 0.06. These values were much lower than the Mendelian value of 0.75. This is an indication that snails have not been purified through artificial breeding. Estimate of genetic distance between the two ectotypes were 0.060, 0.005 and 0.063 at yellow, light yellow and milky white loci, respectively. This shows that the ectotypes are closely related at the egg shell colour loci. Key words: Genotype, phenotype, snail egg, shell colour, variations.