Fitness: Darwinian Survival & Reproduction

In evolutionary biology, specifically within the context described by Darwin, Fitness refers to the ability of an organism to thrive and pass on its genes to the next generation.

This involves two key components:

• Survival: The organism must be able to survive environmental challenges.
• Reproduction: The organism must produce a significant number of fertile offspring.

Therefore, the term that specifically describes the ability of an organism to survive and produce a large number of fertile offspring in the Darwinian sense is Fitness.

Why Other Options Are Incorrect

• Selection: This is the process by which organisms with traits better suited to their environment tend to survive and reproduce more offspring. It's related to fitness but isn't the measure itself.
• Intersexual competition: This is a specific type of competition (often mate choice) that can influence reproductive success, but it's only one aspect contributing to overall fitness.
• Evolution: This is the broader outcome of changes in heritable traits within populations over generations, driven partly by fitness differences.