Quantitative Differentiation of Phenotypic Traits and Correlations between Achatina achatina and Achatina fulica Snails Based on Five Whorls

Three hundred (300) adult black-skinned snails, consisting of one hundred and fifty (150) snails each of A. achatina and A. fulica with 5 whorls were procured from a snail farm in Ogun state, Nigeria and used for this study. The body weights of the snails used ranged from 130.82 g to 268.70 g (average 136.89 g) for A. achatina species, and 48.70 g to 120.10 g (average 61.20 g) for A. fulica respectively. The results obtained in this study indicated that genetically, the A. achatina species are heavier and larger than the A. fulica counterpart with the same number of whorls (5). The results of the phenotypic correlation coefficient among the phenotypic traits of the two species of snails showed negative, weak, low significant (P<0.05) and mostly non-significant (P>0.05) differences between body weight and other phenotypic traits studied. The positive, low significant (P>0.05) phenotypic correlation coefficient (rp) obtained was r = 0.531 between body weight and aperture width, and r = 0.561between aperture width and spiral width respectively for A. achatina species of snails. The only positive and highly significant (P<0.01) phenotypic correlation coefficient of r = 0.610 was obtained between body shell width and aperture width for the same A. achatina species of snails. Species type, age and size differences of the snails used, number of whorls and body weight ranges have high effects on phenotypic trait differentiation and phenotypic correlation coefficient of estimation. Thus, the phenotypic traits of A. achatina and A. fulica species of snails studied could be selected for quantitative differentiation and characterization snails.