For spider monkeys, several of these hypotheses have been
proffered as possible explanations for diversification and speciation.
For example, Froehlich et al. (1991) suggested that a combination
of the river barrier and refugia hypotheses might explain
patterns of speciation in spider monkeys, while Medeiros et al.
(1997) suggested that the contraction and expansion of tropical
forest refugia during the Pleistocene is the most plausible scenario
for explaining spider monkey diversity generally and the origins of
A. paniscus in particular.