The Challenge of Conserving Amphibian Megadiversity in Madagascar

Frogs from Madagascar constitute one of the richest groups of amphibian fauna in the world, with currently 238 described species; caecilians and salamanders are absent [1]. Several frog radiations of the island are species-rich and parallel lemurs and tenrecs in their astonishing morphological and ecological diversity. According to the Global Amphibian Assessment (GAA), Madagascar ranks as the country with the 12th highest amphibian species richness [2,3] (see also http://www.globalamphibians.org), but this is likely an underestimate, because an additional 182 candidate species have been identifi ed since [1]. Diversity is concentrated in rainforests and can locally reach over 100 species. Impressively, 100% of the autochthonous species and 88% of the genera are strictly endemic to Madagascar and its inshore islands [1]. Most of these species belong to two radiations of astonishing ecomorphological and reproductive diversity, the mantellids and the scaphiophrynine plus cophyline microhylids [4,5] (Figure 1). So far, no extinctions of amphibian species have been reported from Madagascar, and chytridiomycosis, a threat for amphibians globally [6,7], has not been detected [8]. Of 220 species assessed by the World Conservation Union (IUCN), nine are listed as Critically Endangered, 21 Endangered, and 25 Vulnerable [3]. This proportion of 25% threatened species is higher than the per-country average of 12%, but lower than that detected globally (32%) and those in various other amphibian hot spots such as Sri Lanka (63%), Mexico (54%), Ecuador (37%), or Colombia (30%) [2]. At fi rst glance, it might seem paradoxical to advocate amphibian conservation actions for a place where catastrophic declines have not yet been detected. However, we argue here that the unique combination of three factors qualifi es Madagascar as a top priority for amphibian conservation: (a) an endemic, diverse amphibian fauna, as yet unaffected by emergent diseases, exists; (b) heavy anthropogenic pressures are put on the remaining primary vegetation and amphibian populations; and (c) a strong commitment of the national government to improve conserving biodiversity is present. In other words, Madagascar represents a tractable opportunity to apply what has been learned from the devastated amphibian faunas of areas such as the Neotropics and Australia. In Madagascar, amphibian conservation efforts have the possibility of being pro-active, rather than reactive, or simply postmortem. Extinctions of Malagasy amphibians have not yet been detected: in fact, all historically described species have been observed during the past 15 years [3], most in the past 5 years. New populations of rare species are discovered at a constant pace, even if some of them are in small forest fragments. Over 500 frog specimens of almost 80 species sampled from most of Madagascar’s biogeographic regions and elevational zones tested negative for amphibian chytrid infection using both histological and molecular techniques [8]. So far, no amphibian The Challenge of Conserving Amphibian Megadiversity in Madagascar