Final answer:
Organisms in isolation with unlimited resources often lead to adaptive radiation, where a single species diversifies into multiple new ones. An example is the Hawaiian honeycreeper, which evolved into distinct species due to reduced competition and absence of predators.
Step-by-step explanation:
When organisms live in isolation with unlimited resources and no predators, this phenomenon often leads to unique forms of adaptive radiation. This is because isolated environments, like islands, provide the perfect conditions for a single species to diversify into multiple new ones, as they adapt to fill different niches. An illustrative example of this is the Hawaiian honeycreeper, which evolved from one founder species into several distinct forms. Such isolated habitats with abundant resources minimize interspecific competition and predation pressures, which otherwise limit size and speciation rates. This creates an opportunity for species to undergo significant changes, sometimes resulting in island gigantism or a burst in speciation.
Therefore, when considering the provided options, the most accurate answer is 'reproductive success' as it reflects the increased possibility for an organism to have a high rate of survival and procreation under such ideal conditions, potentially leading to a diversification of species known as adaptive radiation.