On the Origin of Species By Means of Natural Selection Or, the Preservation of Favoured Races in the Struggle for Life

Competition universal.

竞争无处不在。

Struggle for life most severe between individuals and varieties of the same species; often severe between species of the same genus.

同种个体和变种之间的生存斗争最为激烈；同一属的不同物种之间也常常如此。