Investigating diversity patterns and community dynamics of herpetofauna communities in a small Afrotropical wetland, Uganda

Recent research has increasingly focused on the biodiversity patterns (community structure and diversity metrics) of amphibians and reptiles in tropical African wetlands. In this regard, Uganda is particularly interesting as, despite its relatively small size, it boasts the greatest biodiversity per unit area in Africa and a significant number of endemic vertebrates. The present study aims to analyse the herpetofauna communities of smaller Ugandan wetlands, using the Kaku-Kiyanja wetland (a 20 km² area) as a study case. In order to study the amphibian and reptile communities, we employed a suite of field methods, including visual surveys, dip-netting and audio-call identification, and we evaluated species richness, evenness and diversity patterns in a suite of different habitats. We also used multivariate statistical techniques (Detrended Correspondence Analysis) for spacing the various species in relation to the six type of areas, and a Poisson Generalised Linear Model with a log link to assess the effects of habitat type and taxonomic family on species abundance. A total of 28 sympatric species were identified, comprising 17 amphibian species and 11 reptile species. However, the estimated species richness for reptiles was substantially higher, as indicated by the Chao-1 estimator and species accumulation (saturation) curve analyses. Our GLM results demonstrate that species abundance was strongly shaped by habitat type, with a particular habitat type (IV, i.e. permanent wetland with open water, with scattered Typha and Cyperus papyrus stands) supporting markedly higher counts and Ptychadenidae disproportionately contributing to overall richness patterns across the landscape. GLMs also revealed significant variation in amphibian community diversity metrics—including Shannon diversity, Simpson index, evenness and species richness—across habitats, with some habitats showing lower diversity and higher dominance by a few species. Overall, these results underscore the ecological richness of the studied wetland despite its limited spatial extent. The species diversity observed in Kaku-Kiyanja is comparable to that documented in significantly larger wetland systems. Its ecological connectivity to surrounding water bodies may explain the relatively high species richness. However, we should acknowledge limitations such as suboptimal sampling, particularly for reptiles. Despite no threatened species being found, agricultural activities pose significant threats to the wetland's biodiversity, warranting future conservation efforts. Keywords: community ecology, Amphibia, Reptilia, diversity metrics, Kaku-Kiyanja wetland, East Africa