Meeting Abstract

P1.37  Friday, Jan. 4  Ecological factors and the biogeography of two morphologically divergent species of African clawless otter (Aonyx) SHABEL, A; BRIM, M*; University of California, Berkeley; University of California, Berkeley shabel@berkeley.edu

The clawless otters of Africa (Aonyx) include two major types: a small-toothed type from the Congo region (A. congicus) and a large-toothed type that is more widespread (A. capensis). Here we relied on a combination of field and museum data to map the major morphological features of Aonyx in relation to vegetation and climate variables, and we generated a predictive model of otter population distribution to identify areas of critical conservation interest. More than 600 Aonyx individuals from 32 countries were identified in 34 museum collections, including 80 paleontological specimens from 31 fossil localities (Lower Pleistocene to present). Molar size in the large-toothed type (A. capensis) was positively correlated with latitude in both fossil and modern contexts, but it is not clear if this is related to diet, climate, or some other factor. The small-toothed type (A. congicus) was found across the lower Guineo-Congolian forest zone, from the Cross River on the Nigeria–Cameroon border to the western branch of the Rift Valley. Extralimital specimens of A. congicus from the Kaimosi/Kakamega region of Kenya were identified at sites with relictual patches of Guineo-Congolian habitat. Whereas the durophagous A. capensis relies heavily on hard-shelled invertebrate prey—including crustaceans—the microdont A. congicus relies on softer foods—including earthworms, eels, lungfish, frogs, and snails (the latter are opened by hand). The Congo clawless otter is apparently unique among the lutrines of the world in having a diet based on soft foods (malakophagy). Ecology, morphology, and biogeography are deeply intertwined in the evolution of the African clawless otters.