The Chugoku Mountains-a Hotspot of Geographical Differentiation of Species(PROCEEDINGS, JSSZ SYMPOSIUM, 2006)

Abstract

Recent taxonomic and phylogeographic studies of various terrestrial organisms in the Chugoku Mountains, western Honshu, Japan, have revealed a number of remarkable geographic differentiations among populations in the mountainous regions. Interestingly, geographical boundaries of those differentiations tend to occur intensively in three areas: 1) Sendai River (eastern part of Tottori Prefecture), 2) Asahi River (Okayama Pref.) and Hino River (western part of Tottori Pref.), 3) Ota River (western part of Hiroshima Pref.) and Takatsu River (western part of Shimane Pref.). Each of these river systems has worked as a geographical barrier that facilitates genetic differentiation among the populations or as a barrier to block dispersal of populations that had already differentiated elsewhere. The current paper reviews various examples of geographic differentiations of terrestrial animals, especially harvestmen and other arthropods, in the Chugoku Mountains and discusses possible factors inducing these population differentiations.