Hybridization and species boundaries in Japanese Tsuga

抄録

The genus Tsuga is an important component of the forests of Japan. There are two endemic, distantly related species which have contrasting habitat preferences. Tsuga diversifolia is a dominant of subalpine forests from northern Honshu to Shikoku island and Tsuga sieboldii is a temperate forest dominant from near sea level to below the subalpine zone from central Honshu to Yakushima Island. Discriminating the species by eye can be difficult, particularly where they come into close proximity at the edge of the subalpine zone. In addition, some authors have described 'rare intermediate' forms at contact zones but it is unknown whether these represent hybrids. This study uses species diagnostic genetic markers to discover if hybridisation occurs between the species and to reveal their stand level distribution at multiple contact zones. These results will improve understanding of the distribution and ecology of these important forest trees.