PRIMARY RESEARCH PAPER Genetic variation, demographic history and phylogeography of tire track eel, Mastacembelus favus (Synbranchiformes: Mastacembelidae) in Southeast Asia Jamsari Amirul Firdaus Jamaluddin . Nam So . Bui Minh Tam . Amirrudin Ahmad . Chaiwut Grudpan . Lawrence M. Page . Md. Zain Khaironizam . Siti Azizah Mohd Nor Received: 13 June 2018 / Revised: 16 May 2019 / Accepted: 28 May 2019 Ó Springer Nature Switzerland AG 2019 Abstract The complex climatic and geological history of Southeast Asia has been hypothesised to determine the most important aspects of the current phylogeographical structure and distribution of living organisms throughout the region. To test existing hypotheses, the genetic structure of the tire track eel, Mastacembelus favus, was investigated using 823 bp of mitochondrial DNA cytochrome b from 469 individuals from 51 localities encompassing its native range. The results classified all haplotypes into two major lineages, Lineage 1, which was further divided into Lineages 1a (lower Mekong, eastern Gulf of Thailand and Malay—Thai Peninsula), 1b (Ban- pakong River), 1c (Chao Phraya, Gulf of Thailand and Malay—Thai Peninsula) and 1d (Khlang Yai River), and Lineage 2, the upper reaches of the lower Mekong and the middle Mekong. Strong genetic discontinuities dated approximately 5 MYA were discovered in the Mekong with limited geographical overlap, suggesting a historically dissected drainage between two sections and species colonisation via different routes. The widespread Lineage 1 showed a strong signature of population expansion during the Pleistocene climate oscillation. Haplotype character- istics in the Malay—Thai Peninsula are hypothesised to result from postglacial dispersal from the Mekong Handling editor: Cecile Fauvelot Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10750-019-03987-3) con- tains supplementary material, which is available to authorized users. J. A. F. Jamaluddin (&) Á Md. Z. Khaironizam Á S. A. Mohd Nor School of Biological Sciences, Universiti Sains Malaysia, Minden, 11800 Pulau Pinang, Malaysia e-mail: jamsariafj@gmail.com N. So Inland Fisheries Research and Development Institute (IFReDI), Fisheries Administration (FiA), #186 Norodom Blvd, PO Box 582, Phnom Penh, Cambodia N. So Mekong River Commision, P.O. Box 623, 576 National Road # 2, Sangkat Chak Angre Krom, Khan Menachey, Phnom Penh, Cambodia B. M. Tam Department of Freshwater Aquaculture, College of Aquaculture and Fisheries, Can Tho University, 2/3 street, Can Tho City, Vietnam A. Ahmad School of Marine and Enviromental Sciences, Universiti Malaysia Terengganu, Kuala Nerus, 21030 Terengganu, Malaysia A. Ahmad Institute of Tropical Biodiversity and Sustainable Development, Universiti Malaysia Terengganu, Kuala Nerus, 21030 Terengganu, Malaysia 123 Hydrobiologia https://doi.org/10.1007/s10750-019-03987-3