Abstract:
:The geographic distribution of diploid and tetraploid cytotypes and cpDNA haplotypes throughout the entire range of Aucuba japonica was investigated. We measured relative genome size using flow cytometry and sequenced two cpDNA intergenic regions, atpB-rbcL and psbA-trnH (GUG). Two haplotypes include both diploids and tetraploids; four others are all tetraploids. Based on the combination of these haplotypes and cytotypes, eight "haplo-cytotypes" can be defined, which show a distinct geographic structure. Two diploid haplo-cytotypes are distributed in the southwestern part and six tetraploid ones in the northeastern part of the Japanese archipelago. Diploid and tetraploid haplo-cytotypes with the same haplotype are, in one case, disjunctively distributed, and in another case, in contact. The phylogenetic relationships of haplo-cytotypes indicate that the traditional circumscription of A. japonica is paraphyletic. One lineage consists of four tetraploid haplo-cytotypes and another of diploid and tetraploid haplo-cytotypes plus A. chinensis. Tetraploidization occurred independently at least three times, once at the base of the former lineage and twice in the latter. Taking the geographic, cytological, and phylogenetic evidence into account, the formation of the present geographic differentiation pattern of haplo-cytotypes through postglacial expansion from glacial refugia is discussed.
journal_name
Am J Botjournal_title
American journal of botanyauthors
Ohi T,Kajita T,Murata Jdoi
10.3732/ajb.90.11.1645subject
Has Abstractpub_date
2003-11-01 00:00:00pages
1645-52issue
11eissn
0002-9122issn
1537-2197pii
90/11/1645journal_volume
90pub_type
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journal_title:American journal of botany
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journal_title:American journal of botany
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journal_title:American journal of botany
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