Advance Publication by J-STAGE Genes & Genetic Systems Received for publication: April 2, 2017 Accepted for publication: February 5, 2018 Published online: April 10, 2018 1 Original paper 2 Signature of positive selection in mitochondrial DNA 3 in Cetartiodactyla 4 5 Satoko Mori1 and Masatoshi Matsunami1,2* 6 7 8 1Laboratory of Ecology and Genetics, Graduate School of Environmental Science, 9 Hokkaido University, N10W5, Kita-ku, Sapporo, Hokkaido 060-0810, Japan 10 2Graduate School of Medicine, University of the Ryukyus, 207, Nishihara-cho, 11 Okinawa 903-0215, Japan 12 13 *Corresponding author. 14 Masatoshi Matsunami 15 207, Nishihara-cho, Okinawa 903-0215, Japan 16 TEL/FAX +81-98-895-1766, Email:
[email protected] 17 18 Running head: Positive selection in mtDNA of Cetartiodactyla 19 20 21 1 22 Abstract 23 Acceleration of the amino acid substitution rate is a good indicator of positive 24 selection in adaptive evolutionary changes of functional genes. Genomic information 25 about mammals has become readily available in recent years, as many researchers have 26 attempted to clarify the adaptive evolution of mammals by examining evolutionary rate 27 change based on multiple loci. The order Cetartiodactyla (Artiodactyla and Cetacea) is 28 one of the most diverse orders of mammals. Species in this order are found throughout 29 all continents and seas, except Antarctica, and they exhibit wide variation in 30 morphology and habitat. Here, we focused on the metabolism-related genes of 31 mitochondrial DNA (mtDNA) in species of the order Cetartiodactyla using 191 mtDNA 32 sequences available in databases. Based on comparisons of the dN/dS ratio (ω) in 12 33 protein-coding genes, ATP8 was shown to have a higher ω value (ω = 0.247) throughout 34 Cetartiodactyla than the other 11 genes (ω < 0.05).