Demographic Analyses in the Japanese Captive Population of Japanese Crested Ibis (Nipponia nippon)

Abstract

Japanese crested ibis (Nipponia nippon) completely disappeared from the wild in 1981, and the last individual indigenous to Japan died in captivity in 2003. Then, as a national project, the Japanese captive population has been established by using 5 individuals derived from the Chinese captive population as founders. In this study, we estimated demographic parameters of the Japanese captive population in order to predict the carrying capacity and the number of newly introduced founders needed to retain the genetic diversity. While a significant population growth was observed, the generation length and the effective population size were found to be still short and small, respectively, suggesting the necessity of the efforts to increase and maintain the genetic diversity including increases of these parameters. Further, assuming that the 5 founders are non-inbred and unrelated, under the condition that the carrying capacity is 200 individuals, the gene diversity after 100 years was estimated to be about 60% with no supplements from China. Therefore, as long as the current results are concerned, continuous introductions of new founders are considered to be exclusively required, although future consecutive demographic analyses should be performed for the reasonable acquisition of the demographic parameter values.