Selection and Inbreeding Depression in Maintenance of a Stock Population of the Apple Snail Pomacea canaliculata

Abstract

A stock population of the apple snail has been maintained for artificial selection without human interference and has become inbred. Hatchability fluctuated significantly among the egg lumps, and average hatchability decreased with the decrease in number of mature snails in the stock population. Heritability of hatchability was estimated from the regression line of hatchabilities of offspring to that of their parents; the value was 0.461. The realized heritability was calculated from the first selection for high and low hatchability, and the values were 0.398 for high hatchability and 1.427 for low hatchability. High heritability probably involved heterotic effects, because of decreased hatchability observed in full-sib mating.