What did Darwin mean by Fitness ?

Explanation

### Step-by-Step Text Solution:

1. **Definition of Fitness**: Darwin's concept of fitness refers to an organism's ability to survive and reproduce in its environment. It encompasses not just physical strength but also adaptability to environmental changes.

2. **Positive Selection**: Fitness is associated with positive selection, meaning that individuals with traits that enhance their survival and reproductive success are more likely to pass those traits to the next generation.

3. **Sexual Selection**: Fitness also involves sexual selection, where individuals with certain advantageous traits are more likely to attract mates, thus increasing their chances of reproducing.

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