Biologists have found more than 500 species of fruit flies on the various hawaiian islands, all apparently descended from a single ancestor species. when this ancestor colonized the island chain, it found few competitors: many insect and fly families present in other regions are absent from the isolated hawaiian islands.

this example illustrates

allopatric speciation
temporal isolation
adaptive radiation
sympatric speciation

The scenario given in the question illustrates ADAPTIVE RADIATION .

Adaptive radiation refers to the process by which living organisms diversify quickly from one ancestral species into several new forms. This usually occurs as a result of favorable conditions, such as availability of resources, absence of competition, absence of predator, new environment, new niche, etc.

Adaptive radiation is considered to be a divergent evolution, because the starting species diverge rapidly into numerous new forms. Thus, adaptive radiation typically results in emergency of new species, which have morphological and physiological traits that are quite different from those of the ancestor species.

i think that it is plants