Tracking the boundary between the Palaearctic and the Oriental region: new insights from dragonflies and damselflies (Odonata)
We aim to define the hotspots, faunal regions and faunal elements of Odonata in Eurasia. We describe the location and the extent of the transition zone between the Palaearctic and Oriental realms.
Odonata are suitable for this study because the number of species in the group is sufficient for the required analyses, their distributions are mostly known, and they are split into the highly dispersive Anisoptera and the weakly dispersive Zygoptera. For our analyses, Eurasia was classified into 63 regions, within which we determined the presence or absence of each of the 1765 Odonata species. We calculated species richness maps and performed cluster analysis and principal components analysis to extract faunal regions and elements.
Occurrence records of Eurasian Odonata were partitioned among three major biogeographical entities: (1) Europe, North Africa and North Asia; (2) India, Indochina and southern China; and (3) northern China, Korea and Japan. Each of these entities has further notable substructures and faunal elements, especially in Southeast Asia. The tropical rain forest region of Southeast Asia is the species diversity hotspot of odonates and has the highest number of (often localized) faunal elements. The northern border of the Oriental region reaches southernmost China and the southern slopes of the Himalayas, but the transitional zone between the Oriental and the Palaearctic region extends much farther north, and includes northern China, Japan and Manchuria. The lower dispersal ability of Zygoptera compared with that of Anisoptera is mirrored in various biogeographical patterns: (1) the Western Palaearctic influence on the Eastern Palaearctic is stronger in Anisoptera than in Zygoptera; (2) Zygoptera have more faunal elements on islands than do Anisoptera; and (3) Zygoptera are isolated by the Strait of Gibraltar, but do not show a finer‐grained structure of their faunal elements on the mainland.
The less severe impact of the ice ages in Southeast Asia resulted in the evolution and survival of Odonata species in many regional refugia. These faunal elements have had a greater impact on the post‐glacial colonization than previously thought and strongly influence the composition of Odonata in East Asia.
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Document Type: Research Article
Publication date: 2013-11-01