Phylogeography of the genus <Emphasis Type="Italic">Ulva</Emphasis> (Ulvophyceae,Chlorophyta), with special reference to the Japanese freshwater and brackish taxa |
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Authors: | Satoshi Shimada Naoko Yokoyama Shogo Arai Masanori Hiraoka |
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Institution: | (1) Creative Research Initiative Sousei, Hokkaido University, Sapporo 060-0810, Japan;(2) Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan;(3) Marine Algal Research Co., Ltd., Shinguu-cho, Kasuya-gun, Fukuoka 811-0114, Japan;(4) Usa Marine Biological Institute, Kochi University, Usa-cho, Tosa, Kochi 785-0167, Japan |
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Abstract: | The nuclear-encoded ITS and associated 5.8S rDNA regions were sequenced for 72 specimens of Ulva collected from 44 rivers across Japan, including U. prolifera Müller from the Shimanto River, Kochi Prefecture, as well as 26 samples originally identified as U. linza L. from 20 coastal marine areas. Sequence data revealed that the samples fall into six distinct clades: the U. flexuosa Wulfen clade (2 samples), the Ulva linza-procera-prolifera (LPP) complex clade (75 samples), Ulva sp. 1 clade (3 samples), Ulva sp. 2 clade (7 samples), Ulva sp. 3 clade (4 samples) and Ulva sp. 4 clade (7 samples). The LPP complex contained a mixture of 26 samples collected from seashores and 49 samples obtained
from rivers, including U. prolifera from the Shimanto River, and GenBank data for U. linza and U. procera Ahlner. The samples of the LPP complex differed by only 0–7 substitutions (0–1.149%). Subsequent phylogeographic analyses
of the LPP complex based on the 5S rDNA spacer region revealed the presence of two further groupings: a group including 22
strictly marine littoral U. linza samples and a U. prolifera group composed of a mixture of 4 marine samples and all 49 river samples. The monophyly of all river samples indicates that
adaptation to low salinity might have occurred only once in the evolutionary history of the LPP complex. |
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Keywords: | Taxonomy River Freshwater Japan Phylogeography Ulva |
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