Harnessing the microbiome for turtle conservation: investigating the protective effects of the eggshell microbiome against the emerging fungal disease Fusariosis using the yellow-spotted Amazon river turtle as a model system

威胁野生动物的真菌病原体的出现呈指数级增加，部分原因是新出现的传染病，栖息地退化、污染和野生动物贸易加剧了这些疾病。虽然由于新出现的真菌病原体导致的两栖动物和蝙蝠数量的灾难性下降已经有了很好的记录，但由于新出现的真菌疾病镰刀菌病而导致的海龟的高死亡率却没有得到太多的关注。这种新出现的疾病是由茄病镰刀菌复合体中的一组相关病原体引起的，在孵化过程中感染龟卵，导致孵化失败，导致所有7种海龟的大量死亡。令人震惊的是，最近在厄瓜多尔亚马逊地区的黄斑亚马逊河龟(Podocnemis Unifilis)中发现了这种病原体，这表明这种病原体可能也会对357种淡水龟和龟构成威胁，其中许多已经濒临灭绝。然而，尽管这种新出现的病原体对海龟的生物多样性构成了迫在眉睫的威胁，但我们对这种真菌疾病的了解很少，包括它的传播动态、致病性以及对海龟宿主的长期健康影响。为了解决这一差距，我们建议使用P.unifilis作为模型系统来研究镰刀菌病害的动态。该物种是自2002年以来由Tipuni生物多样性站/亚马逊实施的保护计划的一部分，根据该计划，蛋在产卵时收集，孵化后在放生前圈养，以避免过度捕捞鸡蛋以供消费和非法宠物交易。沿着这条线，我们将在产蛋点调查镰刀菌感染的环境和母体来源，并监测圈养的卵，以确定致病性和感染发展的特征。此外，我们将研究棕榈油农业导致的栖息地退化如何改变镰刀菌的流行和致病性。最后，我们将测试蛋壳微生物群在调节感染结果和孵化成功方面的作用，目的是确定可以利用的蛋壳微生物来保护海龟。我们对蛋微生物组的发育和组装的了解仅限于鸟类，由于鸟类和海龟之间父母照顾策略的不同，这些机制不适用于海龟。关于卵细菌和真菌微生物群在没有父母照顾的爬行动物(如海龟)中的传播和发育，以及它们在介导病原菌抗性中的功能，目前还缺乏研究。总之，这些研究将极大地扩大我们对镰刀菌作为一种新出现的传染病的理解，以及宿主-微生物群相互作用对海龟健康的作用，从而有助于制定有效的海龟保护策略，以应对正在出现的潜在破坏性威胁。

The emergence of fungal pathogens threatening wildlife has increased exponentially, in part driven by emerging infectious diseases that are exacerbated by habitat degradation, pollution, and wildlife trade. Whilst catastrophic declines in amphibians and bats due to emerging fungal pathogens has been well documented, high mortality in sea turtles due to the emerging fungal disease Fusariosis has received less attention. This emerging disease is caused by the group of related pathogens in the Fusarium solani species complex (FSSC), involved in mass mortality of all seven sea turtle species by infecting turtle eggs during incubation and causing hatching failure. Alarmingly, this pathogen was recently detected in the Yellow-spotted Amazonian river turtle (Podocnemis unifilis) in the Ecuadorian Amazon, suggesting that this pathogen may also pose a threat to the 357 species of freshwater turtles and tortoises, many of which are already endangered. However, despite the imminent threat this emerging pathogen poses towards turtle biodiversity, we have very little understanding of this fungal disease, including its transmission dynamics, pathogenicity, and long-term fitness effects on turtle hosts. To address this gap, we propose to investigate Fusarium disease dynamics using P. unifilis as a model system. This species is part of a conservation program run by the Tipuni Biodiversity Station/Amazon since 2002, whereby eggs are collected at the point of laying and hatchlings are reared in captivity before being released, to avoid overharvesting of eggs for consumption and the illegal pet trade. Along this line, we will investigate the environmental and maternal sources of Fusarium infection at the point of laying and monitor eggs in captivity to characterise pathogenicity and infection development. Moreover, we will examine how habitat degradation due to palm oil agriculture alters Fusarium prevalence and pathogenicity. Lastly, we will test the role of the eggshell microbiome, which has recently been linked to Fusarium resistance, in mediating infection outcome and hatching success, with an aim of identifying eggshell microbes that can be harnessed for turtle conservation. Our knowledge about the development and assembly of the egg microbiome is limited to avian species and these mechanisms do not apply to turtles due to differences in parental care strategies between birds and turtles. Studies about the transmission and development of the egg bacterial and fungal microbiome in oviparous reptiles without parental care like turtles and their functional role in mediating pathogen resistance are missing. Together, these lines of research will considerably expand our understanding of Fusarium as an emerging infectious disease and the role of host-microbiome interactions for turtle health, thereby contributing to the development of effective turtle conservation strategies in the face of an emerging and potentially devastating threat.