Island Biogeography of the South Korean Coleoptera

Abstract

Since Island Biogeography that physical environment of islands such as island size or island distance affects biodiversity of them come to the fore, many biogeographers have tried to apply the Island Biogeographic rules to several isolated environments. Besides physical environment, however, human disturbance can also affect insular biota if island is not far from mainland and has undergone human disturbance, such as many South Korean islands. In this research, therefore, I comprehended distribution pattern of the South Korean insular Coleoptera and calculated the effect of the relationship between physical environment of islands and species diversity of Coleoptera. I also speculated the specific mechanism of distribution pattern of Coleoptera through collecting samples and testing the hypothesis. Nestedness analysis result showed high nestedness value of South Korean islands for Coleoptera species and the possibility of geographical region of Coleopetran type species. The west coast generally tends to show higher nestedness than the southeast coast so that the west coast seems that undergoes less outside disturbance (human disturbance) such as invasive species from Korean peninsula. Island size was directly proportional to species diversity. However, it was also inversely proportional in big inhabited islands. It is because the islands can support larger human population and undergo severe and continuous human disturbance. Island distance was not correlated with species diversity. However, island distance was directly proportional to the number of macropterous species in the high-nestedness regions. It suggests that macropterous species have advantage over brachypterous species in terms of reaching far islands and colonizing on their own in case of less outside disturbance. To test the difference of distribution of Coleoptera with different wing length, four islands around Boryeong city in Chungcheongnamdo province were surveyed. 755 samples were collected using pitfall-trap and sweeping and identified. Identification result showed the tendency that dominance index was inversely proportional to island distance and the rate of macropterous species. It may be originated from the characteristic of macropterous species such as slow colonization and fewer individuals in restricted area. Therefore, the difference of dispersal ability with wing length may affect species composition of islands. In this research, I calculated and speculated the effect size of classical Island Biogeographic theory and human disturbance in South Korean islands, and also found distribution pattern and the mechanism of the South Korean Coleoptera. This research can be used as base data when predicting species composition and species diversity of uninvestigated islands.