Phenotypic Correlations and Body Weights Prediction Using Morphometric Traits of Snails in Calabar, Nigeria

Abstract

Data on hatchling body weights and morphometric traits (hatchling body shell length and hatchling body shell width) pertaining to two breeds of snails (A. marginata and A. achatina) from hatch to fourth (4 th ) week of age were analyzed. This was used to obtain correlation coefficient of morphometric traits and to generate prediction equations for live body weight of the animals. Strong, positive and significant correlations between hatchling body weight and body shell width (r=0.82) and between hatchling body weight and body shell length (r=0.80) for A. marginata as well as between hatchling body weight and body shell length (r=0.81) and between hatchling body weight and body shell width (r=0.86) for A. achatina were obtained. Low coefficients of determination (R 2 ) were obtained with the range from 4.73% to 41.30% and from 2.12% to 50.20% for A. marginata and A. achatina respectively. Morphometric traits (Hatchling body shell length and body shell width) best predicted hatchling body weights of A. achatina and not of A. marginata snails. Strong, positive and significant correlations imply that selection for these morphometric traits will lead to improvement of hatchling body weights.

Prediction of body weight using morphometric indices in giant African land snail in three zones of Imo state

“…Most morphometric traits showed a positive regression coefficient ranging from 0.13 to 14.94 for the foot length and shell thickness respectively, although none, except the foot length showed a significantvalue. The mouth length had a negative coefficient value of -18.6.This value agrees 2 with the low R value (4.7%) by Okon and Ibom (2011) for hatching weight and morphometric traits The observed positive regression coefficient values for the shell length, shell thickness, weight of shell, weight of viscera, foot length and foot thickness indicates that a unit increase in any of the morphometric traits, would bring about an expected increase of the body weight by 10.17, 14.94, 5.87, 0.13, 0.88 and 0.24 respectively. The observed negative value of b for mouth length indicates that any unit decrease in the trait will lead to a concordance decrease of the body weight by a factor, 18.60.…”

“…More so, the negative intercept value obtained, signifies that in the absence of all studied morphometric traits, the body weight will decrease by 138.39±110.36. This agrees with the fact that snail weight can be p r e d i c t e d u s i n g q u a n t i t a t i v e o r morphometric trait as predicted by Okon and Ibom (2011). T-test showed that none of the morphometric traits was significant.…”

“…Positive correlation here denotes that the pairs of traits; body weight and morphometric traits have direct relationship or they are controlled by same gene in the same direction as earlier pointed out by Ibom (2009) and Okon et al (2009). However, the value disagrees with the low 2 R value (4.7%) by Okon and Ibom (2011) for hatching weight and morphometric traits. The observed positive regression coefficient values for the morphometric traits (shell length, shell width, shell thickness, shell mouth, weight of shell, weight of viscera, foot length and foot thickness reveals that, a unit increase in any of the traits, would amount to an expected increase of the body weight by a constant amount of 16.84, 11.06, 8.67, 9.02, 0.04, 0.04, 0.46 and 0.08 respectively.…”

Intraspecies variation in nutritive potentials of eggs from two ectotypes of giant African land snail (Archachatina marginata var. saturalis) in Calabar, Nigeria

“…The research was carried out in the Department of Animal Science Snailery and the Analytical Laboratory of the Department, University of Calabar, Calabar, Nigeria. The location and climate of Calabar is as prescribed in Okon and Ibom (2011). One hundred (100) adult A. marginata var.…”

Phenotypic Correlations and Body Weight Prediction of Two Ectotypes of Giant African Land Snails (Archachatina maginata, Swain.) Based on Number of Whorls in Calabar, Nigeria

“…These traits include body weight, shell length, shell width, shell "mouth" length and shell "mouth" width. The authors [13], using multiple regression equations noted that shell length and shell width are better predictors of hatching body weights of A. achtinata than A. marginata juvenile snails.…”