Distribution, genetic diversity and population genetic structure of Cerasus shikokuensis, an endemic species in Shikoku Island

Abstract

Abstract: Cerasus shikokuensis is a flowering cherry that is endemic to Shikoku Island, Japan. As C. shikokuensis grows in a limited area of harsh mountainous landscape in the prefectures of Ehime and Kochi, it has been designated as endangered. To accumulate basic knowledges to conserve this species effectively, we investigated its distribution area, inter- and intra-specific genetic diversity and determined conservation unit. The horizonal distribution of this species ranged between Mt. Ninomori and Mt. Ebira in the mountainous regions of Ishizuchi and Akaishi, respectively. In sites excluding those with serpentine soil, the vertical distribution of this species ranged from 1,700 m to 1,980 m. However, in sites with serpentine soil it ranged from 1,400 m to 1,700 m. Individuals of C. shikokuensis grew in the edges and gaps of Abies veitchii forests, and the shrub on rocky areas. STRUCTURE analysis of nine and one Cerasus species and variety, respectively, including C. shikokuensis showed that C. shikokuensis has distinct genetic cluster from the other species. At the lower altitudinal sites, a putative hybrid individual between C. shikokuensis and C. jamasakura was found. C. shikokuensis were differentiated six populations within a species. Among-population differentiation observed may be due to the isolation of geographical barriers. These six populations should be designated as conservation units and in-situ conservation plan should be constructed based on it.