4. DISCUSSION
The relative roles of rivers and refugia in shaping the high levels of species diversity in tropical rainforests has been widely debated for decades (e.g. Amorim, 1991; Colinvaux, Irion, Räsänen, Bush, & De Mello, 2001; DeMenocal, 2004; Haffer, 1969, 1997; Mayr & O’Hara, 1986; Vitorino, Lima-Ribeiro, Terribile, & Collevatti, 2016). Only recently has it become possible to take an integrative approach to answering these questions with genomic sequencing and paleo-species distribution modeling (Portik et al., 2017; Leaché et al., 2019). Here we tested alternate predictions of the classic river, refuge, and river-refuge hypotheses for terrestrial faunal diversification using a novel study system: the arboreal African snake genus Toxicodryas . We found strong support for the river hypothesis over the refuge and river-refuge hypotheses based on the ages and locations of the populations as well as a lack of support for suitable habitat contraction during the last glacial maximum.