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About the Authors:
Peter H. Adler
* E-mail: [email protected]
Affiliation: School of Agricultural, Forest and Environmental Sciences, Clemson University, Clemson, South Carolina, United States of America
Yao-Te Huang
Affiliations School of Agricultural, Forest and Environmental Sciences, Clemson University, Clemson, South Carolina, United States of America, Department of Plant Medicine, National Chiayi University, Chiayi, Taiwan
Will K. Reeves
Affiliation: United States Air Force School of Aerospace Medicine, Wright-Patterson Air Force Base, Ohio, United States of America
Sam Kyu Kim
Affiliation: Department of Applied Biology, Kangwon National University, Chuncheon, Republic of Korea
Yasushi Otsuka
Affiliation: Department of Infectious Disease Control, Oita University, Oita, Japan
Hiroyuki Takaoka
Affiliation: Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia
Introduction
The biotas of oceanic islands typically owe their origins to dispersal of propagules across open water or land bridges [1]. A question of central interest regarding insular biotas is the source of the colonizers. Various genomic analyses, both chromosomal (macrogenomic) and molecular (microgenomic), have been used to reveal the relationships and geographical origins of island biotas, with varying levels of success [2], [3], [4], [5], [6]. Source-area resolution can be particularly challenging if the colonizing species or their nearest relatives are geographically widespread, with a large number of potential sources from which to colonize.
The Ryukyu ( = Nansei) Islands of Japan lie in an arc along the eastern edge of the East China Sea from the southern end of Japan toward the northern tip of Taiwan. The archipelago consists of about 140 small islands that fall geographically and faunistically into three groups: a northern cluster with a fauna similar to that of Japan, a central group (including Okinawa) with high endemism, and a southern group with faunal elements most similar to those of Taiwan [7]. The central and southern islands share a zoogeographical history separated by the Tokara Strait (Watase Line) from the northern Ryukyus and Japan proper [8].
The islands have a complex geological history of tectonic movements and volcanism, which has spawned conflicting paleogeographic hypotheses [9]. The larger islands originated from the continental shelf, whereas the smaller islands owe their origins to coral or volcanism [8]. Most geological models generally include establishment since the late Miocene, subsequent connections to the Asian mainland via land bridges in various combinations,...