Poor Summary Of Natural Selection

What do the authors mean when they say “survival of the fittest is a poor summary of natural selection?
The statement misrepresents Darwin’s concept of natural selection because, reproduction, not survival, is what makes evolution possible. If a specific specie survived for millions of years, but doesn’t reproduce, the traits will die when that specie eventually dies. The concern on the meaning of the fittest is also flawed- fittest cannot merely mean “those that reproduce,” it must refer to the fit between the organism and the environment.
What is reproduction of the fittest ?
This simple means that only those individuals that can manage the environment will survive and therefore be able to reproduce, thereby carrying on their traits for future generation.
What are adaptations and why do they occur?

Adaptations occurs because it allows an organism to adapt to its environment/habitat, to be able to survive climatic conditions, predators and other organisms who compete for the same food and space. Adaptations, for an organism, can be bigger wings, bigger beaks, bigger eyes, a protein that enhances body temperature, a certain toxin that can be emitted to keep predators or competitors away from food and other resources.
Why do adaptations often fail in novel environment?
According to the text, adaptations fails in novel environment because selection cannot create adaptations to very rare or non existent environments. Instead, it preserves traits that address real-world challenges; if the challenge does not exist, natural selection cannot design an adaptation to meet it. In novel environments adaptations will often fail to reproduce an adaptive response.
What is sexual selection and what causes