Bibliometric analysis of research trends, themes and global collaborations in Nigerian amphibian studies from 1933–2025

Abstract

Nigeria harbours a remarkable diversity of amphibian species. This richness has spurred growing research efforts to advance understanding of its biodiversity. However, despite this long-standing research history, no comprehensive synthesis has yet evaluated the progress achieved or identified existing knowledge gaps to guide future research priorities. This study addresses this gap by analysing publication trends, thematic developments and research patterns in Nigerian amphibian studies from 1933 to August 2025, providing insights to inform and strengthen future research efforts. Published papers were retrieved from multiple bibliographic databases and harmonised into a unified dataset comprising 254 records. Annual publication trends were modelled using binomial regression to evaluate patterns of research growth over time. Species-level research effort, thematic evolution and keyword co-occurrence networks were analysed to trace shifts in research focus and emerging topics. Collaboration structures were assessed through country-based co-authorship networks, while citation performance was examined using age-adjusted models that accounted for collaboration type. The results indicate that amphibian research in Nigeria remained sparse until the early 2000s, after which publication output increased sharply, with 89% of all papers published since 2000 and a peak in 2010. Research activity was heavily concentrated on a few widespread taxa, while more than half of the recorded species appeared in only a single publication. The thematic focus evolved from early studies on parasitology and disease to more recent work on species distribution, biodiversity, phylogeny and genetics. However, conservation-oriented research remained limited and was comparatively undercited. Collaboration networks were dominated by partnerships with institutions in the Global North, with few South–South collaborations or locally led studies. International journals accounted for 89% of publications, whereas a single national outlet anchored domestic scholarly output. Amphibian research in Nigeria has expanded substantially since 2000, but remains uneven across species, research themes and collaborations. Strengthening intra-African co-leadership, supporting open-access publication, improving regional research infrastructure and fostering integrative biodiversity assessments are critical to advancing amphibian science in Nigeria.