Prevalence and genetic diversity of Batrachochytrium dendrobatidis in Central African island and continental amphibian communities

Abstract

The fungal pathogen Batrachochytrium dendrobatidis (Bd) infects hundreds of amphibian species and is implicated in global amphibian declines. Bd is comprised of several lineages that differ in pathogenicity, thus, identifying which Bd strains are present in a given amphibian community is essential for understanding host–pathogen dynamics. The presence of Bd has been confirmed in Central Africa, yet vast expanses of this region have not yet been surveyed for Bd prevalence, and the genetic diversity of Bd is largely unknown in this part of the world. Using retrospective surveys of museum specimens and contemporary field surveys, we estimated the prevalence of Bd in Central African island and continental amphibian assemblages, and genotyped strains of Bd present in each community. Our sampling of museum specimens included just a few individuals collected in the Gulf of Guinea archipelago prior to 1998, yet one of these individuals was Bd‐positive indicating that the pathogen has been on Bioko Island since 1966. We detected Bd across all subsequent sample years in our study and found modest support for a relationship between host life history and Bd prevalence, a positive relationship between prevalence and host community species richness, and no significant relationship between elevation and prevalence. The Global Panzootic Lineage (Bd GPL) was present in all the island and continental amphibian communities we surveyed. Our results are consistent with a long‐term and widespread distribution of Bd in amphibian communities of Gabon and the Gulf of Guinea archipelago.

Community‐level prevalence of a forest pathogen, not individual‐level disease risk, declines with tree diversity

“…When depauperate communities are dominated by disease‐prone species—which is more often the case than not (Gibb et al, 2020; Joseph et al, 2013), even in the absence of dilution mechanisms, less susceptible species added to higher diversity communities would increase the likelihood of observing a decline in overall prevalence. Diversity often negatively covaries with community‐level prevalence (Bradley et al, 2008; Liu et al, 2018; Moore & Borer, 2012), but not always (Hydeman et al, 2017; Milholland et al, 2017; Vaz et al, 2007). Community‐wide disease risk is not uncommon under the dilution effect purview (e.g.…”

Distribution modeling and lineage diversity of the chytrid fungus Batrachochytrium dendrobatidis (Bd) in a central African amphibian hotspot

“…Korea has been recently confirmed as the geographic origin of Bd and its distribution linked to the global commercial trade of amphibian [ 36 ]. Several Bd samples from Gabon and the islands Bioko, São Tomé, and Príncipe were recently characterized as Bd -GPL [ 38 ]. However, our knowledge of the distribution of Bd -GPL elsewhere in the rainforests of Equatorial Africa is poor.…”

The Evolution of Comparative Phylogeography: Putting the Geography (and More) into Comparative Population Genomics

“…Although only three African countries (Madagascar, Côte d'Ivoire, and South Africa) contributed to the pre-2008 literature on comparative phylogeography, 21 countries in Africa published at least one paper in comparative phylogeography after 2008, with an average of 4.85 publications per country in the latter period. There has been growth in Africa as a focus of comparative phylogeography in general ( Hydeman et al 2017 ; Beddek et al 2018 ; van Asch et al 2019 ; Helmstetter et al 2020 ), although the extent to which in-country researchers participate in this increase is variable ( Lorenzen et al 2012 ; Freilich et al 2016 ). Although we record only five comparative phylogeography publications from two countries (Indonesia and Malaysia) in SE Asia before 2008, in the later period ten SE Asian countries (not including Singapore, a Global North country) produced a total of 73 publications, with greater than 7 coming from authors in each of Vietnam, India, Thailand, Cambodia, Philippines, and Indonesia ( fig.…”