At this embryonic stage, tiny genetic differences, changes that might only affect one in a billion traits, make the difference between a hatchling that survives and one that's chomped, stepped on, or even starves to death.
在胚胎期,基因的微小差异可能只会
十亿分之一的性状,但却使有的幼崽能活下来而有的则被吃掉,被踩死甚至活活饿死。