Environmental determinants of Batrachochytrium dendrobatidis and the likelihood of further dispersion in the face of climate change in Texas, USA

Abstract

One of the major drivers of amphibian population declines is Batrachochytrium dendrobatidis (Bd). We sought to identify the major environmental drivers of Bd prevalence in Texas, USA, by drawing results from museum specimens. We sampled one of the largest museum collections in Texas, the Biodiversity Research and Teaching Collections at Texas A&M University. Our sampling focused on the 9 amphibian species with the widest geographical distribution within the state, where we sub-sampled 30% of each species per decade from 1930 to present via skin swabs, totaling 1501 independent sampling events, and used quantitative real-time PCR (qPCR) to detect pathogen presence. We analyzed several geo-referenced variables describing climatic conditions to identify potential factors influencing the likelihood of presence of Bd using boosted regression trees. Our final model suggests the most influential variables are mean temperature of driest quarter, annual mean temperature, temperature annual range, and mean diurnal range. The most likely suitable range for Bd is currently found in the Blackland Prairie and Cross Timbers ecoregions. Results of our future (to the year 2040) projections suggest that Bd could expand its current distribution. Our model could play an important role when developing an integrated conservation plan through (1) focusing future field work on locations with a high likelihood of presence, (2) assisting in the choice of locations for restoration, and (3) developing future research plans including those necessary for projecting reactions to climate change. Our model also could integrate new presence data of Bd when they become available to enhance prediction precision.

Importance of Anthropogenic Determinants of Tubastraea coccinea Invasion in the Northern Gulf of Mexico

“…The selection of specific independent variables may have markedly changed the model development and likelihood estimates [41], which is a general problem related to structural uncertainty in the quantitative representation of natural systems [50,51]. In our study, the possibility always remains that we failed to include some important independent variables, and that the relative importance of those variables we included depends on the current state of the system [35,40]. The availability of additional data on the biological process (e.g., coexistence and competition) and environmental variables (e.g., suspended sediments and current direction), as well as the functional relationships between the variables and the stage of invasion, would likely enhance the prediction precision [52][53][54].…”

“…Species distribution models and ecological niche models have been increasingly used to address a variety of ecological issues involving endangered species, invasive species, and emergent infectious diseases [35][36][37]. Many approaches, ranging from statistical methods to machine learning methods, have been developed and applied.…”

Mites as a Potential Path for Ce-Ti Exposure of Amphibians

“…Together with freshwater fish, amphibians are the most endangered class among the vertebrate groups, with a functional loss of 27% (Toussaint et al, 2021). Causes for these declines are diverse including habitat destruction (Calderón et al, 2019;Borzée et al, 2021), disease (Kriger and Hero, 2009;Herczeg et al, 2021), exposure to pesticides and chemicals (Pinto-Vidal et al, 2021;Goessens et al, 2022), and climate change (Velasco et al, 2021;Villamizar-Gomez et al, 2021). Even in natural protected areas, the steady decline of amphibian populations calls for more studies to be undertaken in pristine or rural areas to assess the extent of the threats worldwide (Green et al, 2020).…”