How is evolutionary fitness defined?

Evolutionary fitness is defined as the success of an organism's ability to survive and reproduce in its environment. This concept encompasses not just the survival of an individual but also how well it can pass its genes to the next generation. Fitness is often measured in terms of the number of offspring an organism produces that survive to reproduce themselves, which directly relates to the propagation of its genetic material in future generations.

The emphasis on survival and reproductive success highlights that it's not merely about surviving in a given environment; it's about contributing to the gene pool. Consequently, organisms that are more fit are those whose traits allow them to not only survive but also reproduce effectively, ensuring their genetic legacy continues. This measure of fitness is foundational in understanding natural selection, where advantageous traits become more common in a population because they enhance reproductive success.

In contrast, options that focus solely on adaptability to climate, genetic diversity, or the influence of environmental changes, while relevant to evolution as a whole, do not capture the essence of evolutionary fitness as clearly as the definition centered on survival and reproductive success does.