Lack of spatial and temporal genetic structure of Japanese eel (Anguilla japonica) populations
Japanese eel (Anguilla japonica) is an important food source in East Asia whose population has dramatically declined since the 1970s. Despite past analysis with DNA sequencing, microsatellite and isozyme methods, management decisions remain hampered by contradictory findings. For example, it remains unresolved whether Japanese eels are a single panmictic population or whether they harbor significant substructure. Accurate assessment of population genetic substructure, both spatial and temporal, is essential for determining the relevant number of distinct management units appropriate for this species. In the present study, we assayed genetic variation genome-wide using Restriction Site Associated DNA Sequencing (RAD-seq) technology to analyze the population genetic structure of Japanese eels. For analysis of temporal isolation, five “cohort” samples were collected yearly from 2005 to 2009 in the Yangtze River Estuary. For analysis of spatial structure, five “arrival wave” samples were collected in China in 2009, and two arrival wave samples were collected in Japan in 2001. In each cohort of each arrival wave, five individuals were collected for a total of 55 eels sampled. In total, 214,210 loci were identified from these individuals, 106,652 of which satisfied quality checks and were retained for further analysis. There was relatively little population differentiation between arrival waves and cohorts collected either at different locations during the same year (Fst = 0.077) or at the same location collected over subsequent years (Fst = 0.082), and locations displayed no consistent isolation-by-distance.
KeywordsAnguilla japonica Japanese eel Population genetic structure RAD-seq Temporal and spatial
We sincerely thank Dr. Minhui Wang for assistance with data analysis. Research supported by the Cornell China Faculty Development Program,the National Natural Science Foundation of China (31201995), the China-ASEAN Maritime Cooperation Fund from Shanghai University, the Shanghai Municipal Agricultural Commission (No. 2013 2–2), the Shanghai Municipal Science and Technology Commission of Chongming (Grant No. 13231203504) and the Open Foundation of Engineering Research Centre of Modern Industrial Technology for Eels (No. RE201501), Ministry of Education. ERD is supported by NIH F32 DK109595.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Baltazar-Soares M, Biastoch A, Harrod C, Hanel R, Marohn L, Prigge E, Evans D, Bodles K, Behrens E, Böning CW, Eizaguirre C (2014) Recruitment collapse and population structure of the european eel shaped by local ocean current dynamics. Curr Biol 24:104–108. https://doi.org/10.1016/j.cub.2013.11.031 CrossRefGoogle Scholar
- Chan I, Chan D, Lee S, Tsukamoto K (1997) Genetic variability of the Japanese eel Anguilla japonica (Temminck & Schlegel) related to latitude. Ecol Freshw Fish 6:45–49. https://doi.org/10.1111/j.1600-0633.1997.tb00141.x CrossRefGoogle Scholar
- Chang K, Han Y, Tzeng W (2007) Population genetic structure among intra-annual arrival waves of the Japanese Eel. Zool Stud 46:583–590Google Scholar
- Han Y, Iizuka Y, Tzeng W (2010b) Does variable habitat usage by the Japanese eel lead to population genetic differentiation? Zool Stud 49:392–397Google Scholar
- Hedgecock D (1994) Does variance in reproductive success limit effective population sizes of marine organisms? Genet Evol Aquat Org 122–134Google Scholar
- Hellberg ME, Burton RS, Neigel JE, Palumbi SR (2002) Genetic assesment of connectivity among marine populations. Bull Mar Sci 70:273–290Google Scholar
- Helyar SJ, Hemmer-Hansen J, Bekkevold D, Taylor MI, Ogden R, Limborg MT, Cariani A, Maes GE, Diopere E, Carvalho GR, NielEE (2011) Application of SNPs for population genetics of nonmodel organisms: New opportunities and challenges. Mol Ecol Resour 11:123–136. https://doi.org/10.1111/j.1755-0998.2010.02943.x CrossRefGoogle Scholar
- Henkel CV, Dirks RP, de Wijze DL, Minegishi Y, Aoyama J, Turner B, Knudsen BJ, Bundgaard M, Hvam K, Boetzer M, Pirovano W, Weltzien F, Dufour S, Tsukamoto K, Spaink HP, van den Thillart GE (2012) First draft genome sequence of the Japanese eel, Anguilla japonica. Gene 511:195–201. https://doi.org/10.1016/j.gene.2012.09.064 CrossRefGoogle Scholar
- Mantel N (1967) The detection of disease clutersing and a generalized regression approach. Cancer Res 27:209–220Google Scholar
- Pujolar JM, Jacobsen MW, Frydenberg J, Als TD, Larsen PE, Maes GE, Zane L, Jian JB, Cheng L, Hansen MM (2013) A resource of genome-wide single-nucleotide polymorphisms generated by RAD tag sequencing in the critically endangered European eel. Mol Ecol Resour 13:706–714. https://doi.org/10.1111/1755-0998.12117 CrossRefGoogle Scholar
- Pujolar JM, Jacobsen MW, Als TD, Frydenberg J, Magnussen E, Jónsson B, Jiang X, Cheng L, Bekkevold D, Maes GE, Bernatchez L, Hansen MM (2014) Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms. Heredity 112:627–637. https://doi.org/10.1038/hdy.2013.145 CrossRefGoogle Scholar
- Ragauskas A, Butkauskas D (2013) The formation of the population genetic structure of the European eel Anguilla anguilla (L.): a short review. Ekologija 59:143–154Google Scholar
- Rousset F (1997) Genetic differentiation and estimation of gene flow from F-statistics under isolation by distance. Genetics 145:1219–1228Google Scholar
- Sang T, Chang H, Chen C, Hui C (1994) Population structure of the Japanese eel, Anguilla japonica. Mol Biol Evol 11:250–260Google Scholar
- Tseng M, Tzeng W, Lee S (2008) Genetic differentiation of the Japanese Eel. Am Fish Soc Symp 58:59–69Google Scholar
- Tsukamoto K, Umezawa A (1990) Early life history and oceanic migration of the eel Anguilla japonica. La mer 188–198Google Scholar
- Weir BS (1996) Genetic data analysis II: methods for discrete population genetic data. Sinauer Assoc Sunderl MA 150–156. https://doi.org/10.1136/jmg.29.3.216