This article is a broad review focused on dragon trees—one of the most famous groups of trees in the world, well known from ancient times. These tertiary relicts are severely endangered in most of the area where they grow. The characteristic features of the dragon tree group are described and the species belonging to this group are listed. This review gathers together current knowledge regarding the taxonomy, evolution, anatomy and morphology, physiology, and ontogeny of arborescent dragon tree species. Attention is also paid to the composition, harvesting, medicinal, and ethnobotanical use of the resin (dragons’ blood). An evaluation of population structure, distribution, ecology, threats, and nature conservation forms the final part of the review. In the conclusions we recommend further avenues of research that will be needed to effectively protect all dragon tree species.
The Soqotra archipelago is one of the most isolated landmasses in the world, situated at the mouth of the Gulf of Aden between the Horn of Africa and southern Arabia. The main island of Soqotra lies not far from the proposed southern migration route of anatomically modern humans out of Africa approximately 60,000 years ago (kya), suggesting the island may harbor traces of that first dispersal. Nothing is known about the timing and origin of the first Soqotri settlers. The oldest historical visitors to the island in the 15th century reported only the presence of an ancient population. We collected samples throughout the island and analyzed mitochondrial DNA and Y-chromosomal variation. We found little African influence among the indigenous people of the island. Although the island population likely experienced founder effects, links to the Arabian Peninsula or southwestern Asia can still be found. In comparison with datasets from neighboring regions, the Soqotri population shows evidence of long-term isolation and autochthonous evolution of several mitochondrial haplogroups. Specifically, we identified two high-frequency founder lineages that have not been detected in any other populations and classified them as a new R0a1a1 subclade. Recent expansion of the novel lineages is consistent with a Holocene settlement of the island approximately 6 kya.
Dragonflies are important bioindicators of aquatic ecosystem health. We discuss the distribution and richness of the 22 dragon- and damselfly species known from the Socotra Archipelago UNESCO World Heritage Site (Yemen) in the western Indian Ocean. We compiled 841 records from literature, field data and museum collections, covering a surveying period of 123 years (1896–2019). Distribution of the only endemic, the Socotra Bluet Azuragrion granti (McLachlan, 1903), an indicator of pristine lotic waters, is updated. Relatively higher dragonfly species richness occurs in eastern Socotra where suitable aquatic habitats are present all year. We observed a significant drop of the number of taxa over several decades in areas in the Hadiboh Plain where human development impacts are strongest. We discuss the indigenous people’s perception of dragonflies to assess the potential of these invertebrates as local flagships for aquatic biodiversity conservation. Our knowledge of the Socotran Odonata remains incomplete, yet they are now among the best studied animal groups in the archipelago. A new record of an Oriental Anax indicates that the island’s dragonfly fauna may yet harbour surprises. Our compilation of odonate records is the first for Socotra and serves as a baseline for future monitoring of the archipelago’s vital aquatic habitats. We converted all records into a geodatabase which we uploaded to an online, freely available web mapping server and mobile application to facilitate research and conservation of the Socotran dragonflies (www.dragonfliesofsocotra.com).
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