A Study of the Geographical Differentiation and Conservation among Psolodesmus mandarinus Populations (Calopterygidae: Odonata)
Date Issued
2012
Date
2012
Author(s)
Lin, Sue-Cheng
Abstract
To investigate the phylogenetic relationship and geographical variation of wing color among the Psolodesmus mandarinus three subspecies, a combination of molecular, morphological, and behavioral approaches was used to guide this research and develop the conservation strategies. Firstly, the molecular phylogenetic analysis of nuclear and mitochondrial genes revealed considerable divergence between Yaeyama’s populations (subspecies kuroiwae) and Taiwanese populations (included subspecies mandarinus and dorothea). Furthermore, two mitochondrial lineages (east and west) existed in Taiwan. The eastern Taiwan lineage included these individuals belonging to dorothea, and the western Taiwan lineage included both dorothea and mandarinus. Because of the genetic diversity of mitochondrial gene was much lower in northwestern Taiwan region and two subspecies shared a common haplotype, it is probable the populations of manadrinus were derived from the northward expansion of dorothea populations. Secondarily, Yaeyama’s populations (kuroiwae) and Taiwanese populations (mandarinus and dorothea) could be exactly discriminated by the morphometrical analysis of wing pterostigma. Previous studies reported the wing color differences between mandarinus and dorothea, our results illustrated that the wing color traits gradually changed across the populations in northern Taiwan. It would be hard to discriminate two subspecies and determine the distribution limits. In contrast, the female wing size shifted dramatically at 24.19 degree (between central and northern Taiwan) which was close to the current criteria (24.33 degree) for dividing two subspecies. Because of both the wing color trait and female wing size changed across the populations of manadrinus in northern Taiwan, it is probable these traits may form co-adapted trait complexes and to cope with a different selection regime in northern Taiwan. Thirdly, the field observations of mating behavior in mandarinus and dorothea populations demonstrated that two subspecies possessed the same kind of female preference for exaggerated male coloration. Thus, the differentiation of wing color trait could not be interpreted only by using sexual selection. If the wing color trait and life history trait formed co-adapted trait complexes in northern Taiwan, the fitness of female preference would be difference between mandarinus and dorothea. Because of the positive fitness effect in female preference for mandarinus populations, wing color traits gradually changed across the northern Taiwan. On the contrary, the negative fitness effect in female preference for dorothea populations, the hyaline wing is maintained by a combination of sexual selection and natural selection. Finally, Psolodesmus is the only one endemic genus of damselflies in Taiwan and Yaeyama. The variety of wing color provided an ideal explanation case for biodiversity education. It also could be used as a biological indicator for monitoring stream ecosystem and global warming. Above all, we suggested developing an educational and recreational program for pursuing the goals of research, conservation and sustainable utilization.
Subjects
Psolodesmus mandarinus
subspecies
geographical differentiation
conservation
damselfly
Taiwan
Type
thesis
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