Darwin held that many more individuals are produced 句子分析

Darwin held that many more individuals are produced than can find food and survive into adulthood.
句子可以这样改写
Darwin maintained that nature produces more individuals than there is food for them to survive into adulthood
达尔文认为,大自然生下个体远比可以让他们生存到成年的食物更多
换句话说
struggle for survival的个体是比can find food and survive into adulthood的更多,
而那些找不到 food 的不能 survive into adulthood .

A struggle for survival follows
跟随而来的是为生存而争斗。
这种“争斗”，是个体之间的争斗，不是指某个个体的争斗。所以不存在个体的数量问题。

更多。 struggle for survival的是挣扎的动物。 can find food and survive into adulthood.那是挣扎成功活下来的动物。 是包含与被包含的关系。