Bull. Plankton Soc. Japan 56(1): 47-51, 2009

Size: px

Start display at page:

Download "Bull. Plankton Soc. Japan 56(1): 47-51, 2009"

大借聪雷
5 years ago
Views:

1 マイクロサテライトによる Cochlodinium polykrikoides の個体群構造解析誌名日本プランクトン学会報 ISSN 著者巻 / 号長井, 敏西谷, 豪 56 巻 1 号掲載ページ p 発行年月 2009 年 2 月農林水産省農林水産技術会議事務局筑波産学連携支援センター Tsukuba Business-Academia Cooperation Support Center, Agriculture, Forestry and Fisheries Research Council Secretariat

2 Cochlodinium polykrikoides 47 Cochlodinium polykrikoides Genetic structure of Cochlodinium polykrikoides populations revealed by microsatellite polymorphism S6IDH=> N6<6> 6C9 GD= N>H=>I6C> Fisheries Research Agency of Japan. National Research Institute of Fisheries and Environment of Inland Sea, Maruishi, Hatsukaichi, Hiroshima , Japan Corresponding author: snagai@a#rc.go.jp Abstract To reveal the process of population expansion and ascertain the origin of the Sea of Japan population of the noxious red tide forming dinoflagellate Cochlodinium polykrikoides, 13samples, isolated from 11 di#erent localities along the Japanese and Korean coasts, were analyzed using ten polymorphic microsatellites. Population genetic analyses such as population di#erentiation and assignment tests identified three clusters, i.e. 1) the Sea of Japan samples, 2) Yatsushiro Sea (Kumamoto Pref.) samples and 3) the Seto Inland Sea with pacific samples, indicating the genetic structuring of 13 C. polykrikoides samples into three distinct populations. The proportion of shared alleles in paired individuals (P SAxy )between samples from the Sea of Japan and other samples was very low, indicating that a large genetic barrier has occurred between these two populations. No significant relationship between genetic distance versus geographical distance and almost no genetic distance was detected between paired samples within the Sea of Japan, although there is a distance of 600 km at maximum. In addition, the P SAxy data values for samples within the Sea of Japan, samples were much higher than for those in other areas clearly showing a strong gene flow from west to east along the Japanese coast, i.e. a large scale transfer of Cochlodinium, has occurred by the Tushima Warm Current. For the P SAxy data for the Seto Inland Sea and Pacific samples, individuals showing relatively high P SAxy were concentrated in the three areas of Nagasaki (NAG), Hyogo (HYO) and Mie (MIE) Prefecture, suggesting that frequent gene flow by human-assisted dispersal through the translocation of pearl oyster spats may have occurred between these locations, despite NAG being separated from MIE by a long distance (ca. 700 km). In this study, significant population di#erences suggested that genetically distinct populations of C. polykrikoides have been locally established in the Seto Inland Sea from the pacific populations. No significant di#erences and a markedly low genetic distance within Yatsushiro Sea samples collected at the same location but in di#erent years, indicated the stability of the genetic structures. Considering these data, C. polykrikoides has over wintered and survived as vegetative populations in the water columns of each local water mass, where the lowest water temperature is perhaps 10, implying possible settlement in these coastal areas after new introductions. This scenario may point to one of the processes of population expansion and globalization in C. polykrikoides in temperate regions. In addition, rising water temperatures by global warming e#ects would also help their survival during cold winters and further population expansions. Key words: Cochlodinium polykrikoides, gene flow, genetic structuring, dinoflagellate, microsatellites Cochlodinium polykrikoides 1) 2) ) 4) (1.3 divisions day 1 ) Kim et al. 2004, 2006 hyaline cyst (Kim et al. 2002). hyaline cyst

48 56 1 (2009) 1975 1980 2000 C. polykrikoides 15 (Nishitani et al. 2007). C. polykrikoides (1) DNA 11 421 (Fig. 1, Table 1).

3 (2009) C. polykrikoides 15 (Nishitani et al. 2007). C. polykrikoides (1) DNA (Fig. 1, Table 1) DNeasy Plant Mini Kit (QIAGEN) DNA (2) 15 PCR 10 DNA PCR PCR 10 PCR PCR 1 N Haploid RNA (LSU) (Ki & Han 2008). 3 (Iwataki et al. 2008). PCR-RFLP LSU , (Nei 1973) ( ) UPGMA (Fig. 2) 11 Table 1. Sampling collection information for Cochlodinium polykrikoides. Abbreviation Area Sampling year sample size Fig. 1. Sampling locations, where seawater sampled containing C. polykrikoides were obtained. In Korea (KOR) and Kumamoto (KUM), samples were taken from the same points but in di#erent years. Detailed information for the sample collection and the abbreviation for the sampling sites are given in Table 1. OIT Inokushi Bay NAG Kujukushima HAR Harima-nada KOR05 Yeosu TSU Asou Bay TOT Nagawase MIE Gokasyo Bay KUM06 Yatsushiro Sea KYO Kurita Bay KAG Yamagawa Bay KOC Nomi Bay KUM07 Yatsushiro Sea KOR07 Korea, Yeosu

Cochlodinium polykrikoides 49 Fig. 2. Fig. 4. Fig. 3. Fig. 2. UPGMA tree of 13 populations of Cochlodinium polykrikoides based on Nei s genetic distance (Nei 1972).

a, Assignment of 421 individuals into K genetically distinguishable groups. Each individual is represented by a vertical bar colored according to the assigned groups.

polykrikoides, numbered as in Fig. 3a and color-coded following Bayesian clustering results for three groups in the lower band of Fig. 3a. Fig. 4.

4 Cochlodinium polykrikoides 49 Fig. 2. Fig. 4. Fig. 3. Fig. 2. UPGMA tree of 13 populations of Cochlodinium polykrikoides based on Nei s genetic distance (Nei 1972). Bootstrap values ( 50 ) are placed close to each node. Fig. 3. Population structure based on 10 microsatellite loci of Cochlodinium polykrikoides as estimated by genotypic clustering in STRUCTURE. a, Assignment of 421 individuals into K genetically distinguishable groups. Each individual is represented by a vertical bar colored according to the assigned groups. The upper and lower bands show the most stable and likely assignments estimated by STRUCTURE (at K 2 andk 3) (see text). b, geographical location of sampled populations of C. polykrikoides, numbered as in Fig. 3a and color-coded following Bayesian clustering results for three groups in the lower band of Fig. 3a. Fig. 4. Gene flow inferred from proportion of shared alleles between the individuals (P SAxy ). The pairwise genetic relatedness between individuals were examined based on the proportion of shared alleles between the individuals (P SAxy ) according to Chakraborty and Jin (1993). Bidirectional arrows show the percentage of individuals shared greater than 7 alleles between pairwise populations. In the location of Korea and Kumamoto, the symbols of two populations collected in the same point were separately drawn in this figure for convenience of reference. Circles are shown the locations of NAG and MIE, where are the major centers of aqua cultures of Japanese pearl oysters in Japan.

5 (2009) 3 1) 2) 3) STRUC- TURE (Pritchard et al. 2000) 2 3 UPGMA (Fig. 3) , (Chakraborty & Jin 1993) ( ) (Fig. 4). 1) 2) 3) C. polykrikoides a 2005 C. polykrikoides C. polykrikoides C. polykrikoides (Fig. 2, Fig. 3), 2008 C. polykrikoides

6 Cochlodinium polykrikoides 51 Chang-Hoon Kim Chang Kyu Lee Chakraborty, R. & L. Jin Determination of relatedness between individuals by DNA fingerprinting. Hum. Biol. 65: Iwataki, M., H. Kawami, K. Mizushima, C. M. Mikulski, G. J. Doucette, J. R. Relox Jr., A. Anton, Y. Fukuyo & K. Matsuoka Phylogenetic relationships in the harmful dinoflagellate Cochlodinium polykrikoides (Gymnodiniales, Dinophyceae) inferred from LSU rdna sequences. Harmful Algae 7: Ki, J. S. & M. S. Han Implications of complete nuclear large subunit ribosomal RNA molecules from the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) and relatives. Biochem. Syst. Ecol. 36: Kim C. H., H. J. Cho, J. B. Shin, C. H. Moon & K. Matsuoka Regeneration from hyaline cysts of Cochlodinium polykrikoides (Gymnodiniales, Dinophyceae), a red tide organism along the Korean coast. Phycologia 41: Kim D. I., Y. Matsuyama, S. Nagasoe, M. Yamaguchi, Y. H. Yoon, Y. Oshima, N. Imada & T. Honjo E#ects of temperature, salinity and irradiance on the growth of the harmful red tide dinoflagellate Cochlodinium polykrikoides Margalef (Dinophyceae). J. Plankton Res. 26: (2) pp Cochlodinium polykrikoides Margalef 52: Nei, M Genetic distance between populations. Amer. Natur. 16: Nei, M Analysis of gene diversity in subdivided populations. Proc. Natl. Acad. Sci. USA 70: Nishitani, G., S. Nagai, S. Sakamoto, C. L. Lian, T. Nishikawa, C. K. Lee, R. Uji, S. Itakura & M. Yamaguchi Development of microsatellite markers in the noxious red tide-causing algae Cochlodinium polykrikoides (Dinophyceae), Mol. Ecol. Notes 7: Pritchard, J. K., S. M. Matthew & P. Donnelly Inference of population structure using multilocus genotype data. Genetics 155: Cochlodinium polykrikoides 32:

Bull. Plankton Soc. Japan 56(2): , 2009

Bull. Plankton Soc. Japan 56(2): , 2009 自然史系博物館の GBIF への貢献誌名日本プランクトン学会報 ISSN 03878961 著者巻 / 号松浦, 啓一 56 巻 2 号掲載ページ p. 169-173 発行年月 2009 年 8 月農林水産省農林水産技術会議事務局筑波産学連携支援センター Tsukuba Business-Academia Cooperation Support Center, Agriculture,