Sandelia bainsii is a range-restricted and highly threatened freshwater fish endemic to South Africa. Recent genetic evidence suggests that this species comprises three allopatrically distributed lineages that have been informally designated as Sandelia sp. 'Kowie', Sandelia sp. 'Keiskamma' and Sandelia sp. 'Buffalo'. As these lineages have only been recently identified, and are likely to face a high risk of extinction due to restricted distributions, there is critical need for generating ecological information to guide conservation prioritisation. The present study compared the historical and current distribution patterns, together with the habitat associations of Sandelia sp. 'Kowie' in the Koonap and Kat rivers, tributaries of the Great Fish River. Our study indicated that this lineage has been extirpated from one of the three localities in the Koonap River where it was historically abundant. In the Kat River, the current distribution of Sandelia sp. 'Kowie' was comparable to its historical range, but its future persistence is threatened by the presence of non-native piscivores, instream physical barriers, and potential future exploration for shale gas and infrastructure development in the Karoo Basin. A generalised hurdle negative binomial model revealed that although this lineage's probability of occurrence was high in habitats with boulder and sand substrates, and low conductivity, habitat characteristics were poor predictors of its abundance. It was, thus, postulated that the current range of this lineage probably represent the only available habitats for the persistence of different life stages for this taxon. Alternatively, the observed patterns may suggest the possibility of a shift in habitat associations, possibly for optimum utilisation of the remaining refugia within this river system. Immediate conservation measures should focus on preventing the spread on non-native invasive fishes, whereas future studies should evaluate the impacts of population fragmentation and identifying appropriate intervention measures to maintain this lineage's long-term adaptive potential.

中文翻译：

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Sandelia bainsii (Teleostei: Anabantidae) 的分布模式和栖息地关联，一种高度受威胁的窄范围特有淡水鱼

Sandelia bainsii 是南非特有的一种范围受限且高度受威胁的淡水鱼。最近的遗传证据表明，该物种包括三个异域分布的谱系，这些谱系被非正式地命名为 Sandelia sp。'Kowie'，Sandelia sp。'Keiskamma' 和 Sandelia sp。'水牛'。由于这些谱系最近才被确定，并且可能因分布受限而面临灭绝的高风险，因此迫切需要生成生态信息来指导保护优先级。本研究比较了历史和当前的分布模式，以及 Sandelia sp. 的栖息地关联。大鱼河的支流库纳普河和吉河中的“Kowie”。我们的研究表明，该谱系已从历史上丰富的 Koonap 河三个地点之一中灭绝。在吉河，目前分布 Sandelia sp。'Kowie' 与其历史范围相当，但其未来的持久性受到非本地食鱼动物的存在、河内物理障碍以及未来对卡鲁盆地页岩气和基础设施开发的潜在勘探的威胁。广义障碍负二项式模型显示，尽管该谱系在具有巨石和沙质基质且电导率低的栖息地中发生的概率很高，但栖息地特征对其丰度的预测较差。原来如此，假设该谱系的当前范围可能代表该分类群不同生命阶段持续存在的唯一可用栖息地。或者，观察到的模式可能表明栖息地关联发生变化的可能性，可能是为了优化利用该河流系统内剩余的避难所。即时保护措施应侧重于防止非本地入侵鱼类的传播，而未来的研究应评估种群分散的影响并确定适当的干预措施以保持该谱系的长期适应潜力。