Journal of Heredity Advance Access originally published online on February 21, 2008
Journal of Heredity 2008 99(2):202-207; doi:10.1093/jhered/esm129
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Brief Communications |
Estimation of the Time of Divergence between Japanese Mishima Island Cattle and Other Cattle Populations Using Microsatellite DNA Markers
From the National Institute of Livestock and Grassland Science, Tsukuba 305-0901, Japan (Nagamine, Nirasawa, Takahashi, Sasaki, and Ishii); the National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan (Minezawa); the Graduate school of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan (Oda); the Queensland Institute of Medical Research, Royal Brisbane Hospital, Queensland 4029, Australia (Visscher); and the Headquarters, National Agriculture and Food Research Organization, Tsukuba 305-8517, Japan (Furukawa). Yoshitaka Nagamine is now at the Roslin Institute, Roslin, Midlothian EH25 9PS, UK
Address correspondence to Y. Nagamine at the address above, or e-mail: yoshi.nagamine{at}bbsrc.ac.uk.
We applied the theory of random genetic drift to determine the divergence history of a closed cattle population over the relatively short timescale of several hundred years. The divergence history of the closed population of Mishima Island cattle, a national natural treasure of Japan, was examined, and the results were compared with historical documents. Inbreeding depression in the isolated population was investigated for body size and fertility. Twenty-one DNA microsatellite markers in Mishima Island cattle and 3 major breeds from the mainland were genotyped. For the mainland breeds, all 21 or 20 markers were segregating. However, nearly half the number of loci (9 of 21) was fixed in the Island cattle. The average number of alleles per locus of Island cattle was markedly lower than that in the mainland breeds. These results support the theory that Island cattle have been isolated for a considerable period of time. The number of generations of isolation was estimated as 14.1–22.6, and the year of divergence was calculated as 1778–1846. In view of these findings, we propose that Island cattle diverged from the mainland population at around 1800 and were isolated for about 200 years. These estimates are in agreement with historical documents showing that divergence occurred between 1672 and 1880. The total inbreeding coefficient of the present population was predicted to be in the range of 0.51–0.60. However, historical reports dated over 100 years do not support changes in fertility, so that there is no evidence for inbreeding depression.
Corresponding Editor: James Wornack
Received May 25, 2007
Accepted November 14, 2007