Genetically distinct coelacanth population off the northern Tanzanian coast
Masato Nikaidoa,1, Takeshi Sasakia,1,2, J. J. Emersonb, Mitsuto Aibaraa, Semvua I. Mzighania,c, Yohana L. Budebac, Benjamin P. Ngatungac, Masamitsu Iwatad, Yoshitaka Abed, Wen-Hsiung Lie,f,3, and Norihiro Okadaa,3
Author Affiliations
aGraduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Midori-ku, Yokohama 226-8501, Japan;
bDepartment of Integrative Biology, University of California, Berkeley, CA 94720-3140;
cTanzania Fisheries Research Institute, P.O. Box 9750, Dar es Salaam, Tanzania;
dAquamarine Fukushima, Onahama, Iwaki, Fukushima 971-8101, Japan;
eDepartment of Ecology and Evolution, University of Chicago, Chicago, IL 60637; and
fBiodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
Contributed by Wen-Hsiung Li, September 26, 2011 (sent for review May 29, 2011)
Abstract
Since the sensational discovery of a living coelacanth off the east coast of South Africa, the geographic distribution of viable coelacanth populations has been a subject of debate. In the past, the coelacanths off the African mainland were thought to be strays from the Comoros because most coelacanths captured were caught in the waters surrounding the Comoros archipelagos. However, in recent years, a large number of coelacanths were captured off the coast of Tanzania, including nine living specimens observed in a remotely operated vehicles survey. Thus, it is possible that there is a reproducing population inhabiting waters off the Tanzania coast. We have sequenced the complete mitochondrial genomes of 21 Tanzanian and 2 Comoran coelacanths and analyzed these sequences together with two additional full mitochondrial genomes and 47 d-loop sequences from the literature. We found that the coelacanth population off the northern Tanzanian coast is genetically differentiated from those of the southern Tanzania coast and the Comoros, whereas no significant genetic differentiation occurs between the latter two localities. The differentiation between the northern and southern Tanzanian coast populations is consistent with the hypothesis that the existence of northward-flowing ocean current along the Tanzanian coast may reduce or prevent gene flow from the northern to the southern population. Finally, we estimated that the population localized to the southern Tanzanian coast and the Comoros diverged from other coelacanths at least 200,000 y ago. These results indicate that the coelacanths off the northern Tanzania coast are not strays but a genetically distinct group. Our study provides important information for the conservation of this threatened “living fossil.”
Footnotes
↵1M.N. and T.S. contributed to this work.
↵2Present address: Laboratory of Wild Animals, Department of Human and Animal-Plant Relationships, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi-shi, Kanagawa 243-0034, Japan.
↵3To whom correspondence may be addressed. E-mail:nokada@bio.titech.ac.jp or whli@uchicago.edu.
Author contributions: W.-H.L. and N.O. designed research; M.N., T.S., M.A., S.I.M., Y.L.B., B.P.N., M.I., and Y.A. performed research; M.N., T.S., J.J.E., and W.-H.L. analyzed data; and M.N., J.J.E., W.-H.L., and N.O. wrote the paper.
The authors declare no conflict of interest.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos.AP012177–AP012199).
This article contains supporting information online atwww.pnas.org/lookup/suppl/doi:10.1073/pnas.1115675108/-/DCSupplemental.
Freely available online through the PNAS open access option.
