Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, 30-387 Kraków, Poland.
Zoology and Animal Ecology Department, School of Biology, V. N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine.
Dis Aquat Organ. 2024 Aug 1;159:15-27. doi: 10.3354/dao03802.
The chytrid Batrachochytrium dendrobatidis (Bd) is a widespread fungus causing amphibian declines across the globe. Although data on Bd occurrence in Eastern Europe are scarce, a recent species distribution model (SDM) for Bd reported that western and north-western parts of Ukraine are highly suitable to the pathogen. We verified the SDM-predicted range of Bd in Ukraine by sampling amphibians across the country and screening for Bd using qPCR. A total of 446 amphibian samples (tissue and skin swabs) from 11 species were collected from 36 localities. We obtained qPCR-positive results for 33 samples including waterfrogs (Pelophylax esculentus complex) and fire- and yellow-bellied toads (Bombina spp.) from 8 localities. We found that Bd-positive localities had significantly higher predicted Bd habitat suitability than sites that were pathogen-free. Amplification and sequencing of the internal transcribed spacer (ITS) region of samples with the highest Bd load revealed matches with ITS haplotypes of the globally distributed BdGPL strain, and a single case of the BdASIA-2/BdBRAZIL haplotype. We found that Bd was non-randomly distributed across Ukraine, with infections present in the western and north-central forested peripheries of the country with a relatively cool, moist climate. On the other hand, our results suggest that Bd is absent or present in low abundance in the more continental central, southern and eastern regions of Ukraine, corroborating the model-predicted distribution of chytrid fungus. These areas could potentially serve as climatic refugia for Bd-susceptible amphibian hosts.
蛙壶菌（Batrachochytrium dendrobatidis，Bd）是一种广泛分布的真菌，在全球范围内导致了两栖动物的衰落。尽管东欧有关 Bd 发生的数据稀缺，但最近的一项 Bd 物种分布模型（SDM）报告称，乌克兰的西部和西北部是高度适合该病原体的地区。我们通过在全国范围内采集两栖动物样本并使用 qPCR 对 Bd 进行筛查，验证了 SDM 预测的乌克兰 Bd 范围。从 36 个地点采集了来自 11 种的 446 个两栖动物样本（组织和皮肤拭子）。我们从 8 个地点的 33 个样本中获得了 qPCR 阳性结果，这些样本包括青蛙（Pelophylax esculentus 复合体）和火蛙和黄腹蟾蜍（Bombina spp.）。我们发现，Bd 阳性地点的 Bd 栖息地适宜性预测值明显高于无病原体的地点。对 Bd 负荷最高的样本的内部转录间隔区（ITS）区域进行扩增和测序，揭示了与全球分布的 BdGPL 菌株的 ITS 单倍型以及 BdASIA-2/BdBRAZIL 单倍型的匹配。我们发现，Bd 在乌克兰的分布是非随机的，在该国西部和中北部森林边缘的气候较凉爽、潮湿的地区存在感染。另一方面，我们的结果表明，Bd 在乌克兰的中部、南部和东部大陆性更强、更干燥的地区不存在或存在低丰度，这与模型预测的蛙壶菌分布相吻合。这些地区可能是 Bd 易感两栖动物宿主的气候避难所。
