How does natural selection evolve organisms?自然选择怎么进化生物？

Natural selection is the main driving force of biological evolution, which promotes biological evolution through the following key steps:

**Struggle for survival**:
In an environment with limited survival resources, organisms will compete with each other for food, habitat, mates, etc. For example, in a grassland, herbivores will compete for limited grass resources.

**Genetic variation**:
There are genetic differences between individual organisms, which leads to their diversity in morphology, physiology and behavior. For example, birds of the same species may have different feather colors.

**Survival of the fittest**:
Individuals with characteristics that are more adapted to the environment have a better chance of surviving in the struggle for survival. For example, in a cold environment, animals with thicker hair can better maintain body temperature and are more likely to survive.

**Reproductive success**:
Surviving individuals can reproduce offspring and pass on their beneficial genes. For example, fast-running antelopes can avoid natural enemies, so they have more opportunities to reproduce offspring, and the genes for fast running gradually increase in the population.