Role of sex as evolutionary factor from genotype to phenotype

We know different forms of reproduction adopted by living beings, from the simple division of the protozoa, to the complex and modalities of the vertebrates that contemplate codified rituals and preliminary preparations before arriving at the mating.
In nature there is a wide range of reproductive modalities, which is as numerous as the living species. Every reproductive system has a specific procedure and a sexual dimorphism finalized to favor the coupling and strictly suitable for the ecosystem where the union of the sexes takes place.
Such a close relationship between living and environment is a consequence of the evolutionary process in which both share. But the ability to respond to random environmental variations for adapting and evolving with them is an exclusive characteristic of the living, thanks to the reproductive process mediated by sex.
So sexual reproduction is the real engine that promotes evolution.
The infinitely complex way in which sex acts is a subject that always has attracted biologists, and Darwin, with his work on the evolution of the living, was the first to investigate this phenomenon, inaugurating research, which still today has many obscure points.
By this manuscript we are going to try to contribute to the solution of this intriguing mystery.