Major knowledge shortfalls for Colombian Amazonian anurans: Implications for conservation

Abstract

The Amazon boasts the highest anuran species diversity in the world. The Colombian Amazon has the highest rates of illegal deforestation, leading to accelerated species loss. The objective of this review was to identify knowledge shortfalls in anuran research to effectively address conservation efforts. We conducted a systematic literature search from different databases. To this end, we evaluated knowledge gaps in the published literature to pinpoint areas where information is lacking, aiming to address critical topics essential for advancing scientific understanding and informing effective conservation and management strategies. We read the Abstract, Methods, Study Area, Results and supplementary material for each document following the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) protocol. We found 161 documents, with the earliest publications dating back to the 1940s, and the highest productivity occurring since 2000. The diversity of research topics has increased over time. The most studied topics were systematics and taxonomy, natural history, geographic distributions, while the least studied topics (with less than six documents) were cell biology and microbiology, genetics, toxicology, ethnobiology, diet, infectious diseases, biogeography and macroecology. There remains a need for further research in these underrepresented areas. Only 10 species were represented in more than 17 papers and 165 species were represented in less than three publications. Only three species (Allobates femoralis, Dendropsophus parviceps and Phyllomedusa bicolor) were studied from more than 10 topics and, in general, the studies concentrated on adult life stages, maintaining a gap in the knowledge of larval stages (Haeckelian shortfall). We found 296 anuran species reported in the published documents; and the departments of Amazonas, Caquetá and Putumayo had the highest number of studies with great knowledge gaps in Meta, Vichada, Nariño and Cauca. There was an important increase in the collection of primary field data, and the use of biological collections for specimen studies, with 30.6% and 40% of total studies in these periods, respectively, relying on these data sources. However, in the entire 76-year span, there has been only one publication that conducted experiments on anurans, highlighting the considerable lack of eco-physiological studies. Our review did not find a population ecology paper with detailed demographic data or life tables (Prestonian shortfall), although we did uncover six papers reporting abundance data of seven species that could be applied to conservation efforts. We found two papers that reported on functional traits such as reproductive modes and morphological traits (Raunkiæran shortfall); but we did not find a paper on biotic interactions (Eltonian shortfall), species'abiotic tolerances (Hutchinsonian shortfall), or explicit evolutionary patterns (Darwinian shortfall). Only five anuran species were listed in the “Catálogo de Anfibios y Reptiles de Colombia” and only two species have distribution models available on the BioModelos online platform to map Colombian species distribution (Wallacean shortfall). Of the 296 anuran species, 32 are classified under various IUCN threat categories, although these assessments were based solely on geographical distribution data (AOO and EOO) due to the lack of population trend information, resulting in 218 species categorized as of least conservation concern, due to their wide distribution. This study highlights the limited focus on anuran population ecology in the Colombian Amazon, despite its critical role in understanding demographic processes and species conservation. Herpetological research in the Amazon must focus on providing the following critical information for species conservation: (a) long-term participatory population assessments in mature native forests, (b) detection of changes in the abundance and value of species' functional traits in response to landscape anthropogenic transformation and (c) the development and validation of species distribution maps for the Amazonian region. Sharing raw anuran species population and distribution data through open-access platforms are crucial steps for the development of informed conservation strategies for the region. Such data enable early detection of habitat degradation and loss effects and establishes a research agenda for long-term participatory monitoring of anuran species and their habitats.