Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, UK.
Oman Botanic Garden, Muscat, Oman.
Ann Bot. 2019 Oct 18;124(3):411-422. doi: 10.1093/aob/mcz085.
Southern Arabia is a global biodiversity hotspot with a high proportion of endemic desert-adapted plants. Here we examine evidence for a Pleistocene climate refugium in the southern Central Desert of Oman, and its role in driving biogeographical patterns of endemism.
Distribution data for seven narrow-range endemic plants were collected systematically across 195 quadrats, together with incidental and historic records. Important environmental variables relevant to arid coastal areas, including night-time fog and cloud cover, were developed for the study area. Environmental niche models using presence/absence data were built and tuned for each species, and spatial overlap was examined.
A region of the Jiddat Al Arkad reported independent high model suitability for all species. Examination of environmental data across southern Oman indicates that the Jiddat Al Arkad displays a regionally unique climate with higher intra-annual stability, due in part to the influence of the southern monsoon. Despite this, the relative importance of environmental variables was highly differentiated among species, suggesting that characteristic variables such as coastal fog are not major cross-species predictors at this scale.
The co-occurrence of a high number of endemic study species within a narrow monsoon-influenced region is indicative of a refugium with low climate change velocity. Combined with climate analysis, our findings provide strong evidence for a southern Arabian Pleistocene refugium in Oman's Central Desert. We suggest that this refugium has acted as an isolated temperate and mesic island in the desert, resulting in the evolution of these narrow-range endemic flora. Based on the composition of species, this system may represent the northernmost remnant of a continuous belt of mesic vegetation formerly ranging from Africa to Asia, with close links to the flora of East Africa. This has significant implications for future conservation of endemic plants in an arid biodiversity hotspot.
阿拉伯半岛南部是全球生物多样性热点地区，拥有大量适应沙漠环境的特有植物。本研究旨在探讨阿曼中部沙漠南部是否存在更新世气候避难所，并分析其对特有现象形成的影响。
在阿曼南部的 195 个样方中，我们系统地收集了七种分布范围狭窄的特有植物的分布数据，同时收集了偶发和历史记录。为研究区域开发了与干旱沿海地区相关的重要环境变量，包括夜间雾和云量。使用存在/缺失数据的环境生态位模型为每个物种进行构建和调整，并检查空间重叠。
报告称，Jiddat Al Arkad 地区独立高适合度的物种模型数量较多。对阿曼南部的环境数据进行研究表明，Jiddat Al Arkad 气候具有独特的区域特征，年内稳定性较高，部分原因是受到南部季风的影响。尽管如此，物种之间的环境变量相对重要性差异很大，表明在这种规模下，沿海雾等特征变量并不是跨物种的主要预测因子。
在一个受季风影响的狭窄区域内共同出现大量特有研究物种，表明存在一个气候变化速度较慢的避难所。结合气候分析，我们的研究结果为阿曼中部沙漠的阿拉伯半岛更新世避难所提供了有力证据。我们认为，这个避难所是一个孤立的温带和湿润岛屿，导致了这些狭窄分布的特有植物的进化。根据物种组成，该系统可能代表了从前从非洲延伸到亚洲的湿润植被连续带的最北残余部分，与东非的植物区系密切相关。这对保护干旱生物多样性热点地区的特有植物具有重要意义。
