1.How do decrease distance between subjects and verbs in this sentence.
• Species of the genus Drosophila reproduce in a wide range of different resources, including fruits, sap, flowers, mushrooms and cacti. Drosophila species and their resources also exhibit considerable variability in geographic distribution.
Why do you want to decrease the distance between subjects and verbs?
Species . . . reproduce
species, resources . . . exhibit
Those sentences are fine the way they're written.