| Summary: | 碩士 === 東海大學 === 生命科學系 === 96 === We used an endemic Formosan damselfly, Euphaea formosa (Insecta: Odonata: Euphaeidae) in Taiwan to investigate the pattern of contemporary population genetic structure using both mitochondrial cytochrome oxidase II (COII) and nuclear internal transcribed spacer (ITS) genes, and to discuss geohistorical events and life history characteristics that may have contributed to the observed patterns. Our results suggested that there was substantial gene flow among populations. Two distinct haplotype clades, one western restricted and one widespread clade, were identified based on COII phylogeny. The COII western clade, which showed a significant isolation by distance pattern, may colonize Taiwan due greatly to recent glacial events. Historical demography estimated using Bayesian skyline plot (BSP) and mismatch distribution showed a pattern of recent population expansion. Significant negative Tajima’s D and Fu’s FS values coupled with star-like networks of COII widespread clade and ITS also indicate population expansion. We conclude that the colonization and demographic expansion of damselfly populations were likely the result of increased available habitats during late Pleistocene.
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