2.1 Field sampling
Frogs were sampled between the months of March and July in 2013, 2014, and 2015. We collected a total of 191 P. auritus from four sites in Cameroon (Campo Ma’an (CM), N = 29; Ebo forest (EF), N = 24; Ndikiniméki (ND), N = 13; and Takamanda (TM), N = 15), and five sites in Gabon (Gamba Complex (GC), N = 24; Kessala (KS), N = 21; Lopé (LP), N = 18; Monts de Cristal (MC), N = 22; and Minkébé (MK), N = 25) (Fig. 1a).These sites encompassed a range of forest types, namely: lowland rainforest (CM, MK), sub-montane rainforest (EF, TM), forest-savanna ecotone (KS, MC), coastal rainforest (GC), and mixed lowland-agricultural forest (ND). After frogs were euthanized with MS222 solution, muscle and kidney tissue was placed in 95% ethanol for DNA extraction. Male frogs were differentiated from female frogs by the presence of a developed vocal sac, indicated by a dark throat and vocal folds. Frogs that could not be sexed by these secondary sexual characteristics were dissected and sexed by either the type of reproductive organ or by the presence of eggs. All animal handling procedures were carried out according to an approved Institutional Animal Care and Use Committee protocol 12-008. Specimens were deposited at the Museum of Comparative Zoology, Harvard University.