An animal species becomes extinct when it fails to produce enough young is each generation to keep pace with the death-rate.
An animal species becomes extinct when it fails to produce enough young is each generation to keep pace with the death-rate.
不论何种动物，只要每一代不能繁殖出足够的后代，不能与这种动物的死亡数字相平衡，那么这种动物就会逐渐灭绝。