Frugivorous primates require a climate that meets very specific conditions. Lowland nonseasonal tropics. Any disruption in those climate conditions could compromise the viability of fruit specialization in their ecological niche.
Spider monkeys in costa ricas corcovado national park have been found emaciated, near death due to starvation because of too much rain, compromising forest fruit production, and their ability to forage.
A question that i'd appreciate opinion on. To my knowledege, south america lacks forest fig tree that produce large figs, whereas africa has several. Could a large frugivore like a chimp or an oranguatan sustain itself in south americ's forests considering the lack of said large wild figs? Are south america's lowland forests less able to support fruit specialists than africas and maybe even asias lowland forests.