Sexual selection favors individuals with traits that increase their ability to obtain mates, such as mating calls in crickets. using this example, propose a scenario where sexual selection could contribute to divergence in sympatric speciation.

The crickets that are able to make mating calls will mate selectively within each other while those that cannot mate among themselves. If this selective mating continues over time – tens to thousands of years, then the two population could reach a point where they become reproductively isolated to form distinct species.  

Sympatric speciation is the evolution of species from an ancestral population occupying the same geographical location.

just go with your heart buddy

that is wrong, its not thymus.