Final answer:
Recently diverged sympatric species might undergo speciation due to limited gene flow and ecological niche differentiation. Changes in the environment can affect species recognition and mating patterns, potentially leading to reinforcement of divergence or the undermining of speciation.
Step-by-step explanation:
Recently diverged sympatric species are likely to go through speciation if continued gene flow is hindered, and different environmental factors or ecological niches promote separate evolutionary paths. For example, if sympatric speciation occurs in two groups of fish in a lake due to adaptation to different food resources at varying depths, their interaction and breeding would be limited to similar-depth partners. Over time, genetic changes accumulate, leading to increased divergence.
In a scenario where two sympatric species are differentiated by visually distinguishable features, such as color, and a change in the environment (like increased water cloudiness due to pollution) hampers this visual recognition, there might be an increase in hybridization between the two species. If the hybrids are less fit than the parents, natural selection could reinforce divergence between the species, leading to reinforcement of divergence. Conversely, if hybrids are equally or more fit, it might lead to a blending of the species, undermining the speciation process.