A numerical analysis of karyotypes in the genus Pseudotsuga

Abstract

Numerical data were collected from the karyotypes of seven species in the Pseudotsuga genus. These included two North American species, P. macrocarpa and P. menziesii, the latter with two varieties (P. menzeisii var. menziesii and P. menziesii var. glauca) and five Asiatic species, P. japonica from Japan, P. wilsoniana from Taiwan, and P. forrestii, P. sinensis, and P. gaussenii from China. A stepwise discriminant function analysis was employed to test the validity of using karyotype data for characterizing the cytogenetical and the geographical differences of each species. Good discrimination was shown among P. macrocarpa and the Asiatic species. The discrimination among the Asiatic species was further improved when the well-separated P. macrocarpa was omitted. A high level of discrimination was observed between the two P. menziesii varieties. This statistical technique was particularly helpful in selecting variables that best separated the taxa. To our knowledge, these results provide the first reported karyotype numerical analysis for the Pseudotsuga genus as well as the first reported karyotype analysis for P. gaussenii.