Scientists have long known that sex produces greater genetic diversity.  Now, they've shown that sex is the weapon of choice for inter-species genetic arms race.

A University of Indiana study performed the following illustrative experiments on roundworms.

The scientists prepared three groups of roundworms:

1) could reproduce sexually or asexually

2) genetically modified to only reproduce sexually

3) genetically modified to only reproduce asexually

They then introduced an evolving parasite into the three populations. Roundworms in the first population switched from favoring asexual reproduction to sexual reproduction.  In doing so, they increased their genetic diversity and were able to combat the evolving parasite.

The second group coped with the parasite.

The third group, which reproduced asexually and thus lacked genetic diversity, got slaughtered by the parasite.

Genetic superiority is all about diversity, which sexual reproduction enhances.

When species produce diverse offspring, chances are that some of them will have traits that give them advantages over the environment.  These advantaged offspring will thrive and reproduce more, thereby adapting the gene pool of the entire species to the environment.

This well-known process is called natural selection.

Scientists generally thought of it as species adapting to the broad environment.  The University of Indiana research highlighted that it's also intimately involved in the direct competition between species, in this case a parasite evolving to exploit the weakness of the host and the host counter-evolving to defend against new attacks of the parasite.