Variation among Cupressus species from the western hemisphere based on random amplified polymorphic DNAs

Abstract

Random amplified polymorphic DNAs (RAPDs) data were analyzed from all the taxa of Cupressus from the western hemisphere. Populations of Cupressus from Arizona and Texas, USA, were found to cluster in the two groups delimited by Wolf (1948): C. arizonica and C. glabra. These data suggest that these taxa might be better recognized at the specific level as per Wolf (1948), rather than at the varietal level ( Farjon, 1998) or not at all ( Bartel, 1994). A second analysis, which included Chamaecyparis nootkatensis (= Cupressus nootkatensis) and all the taxa of Cupressus from the western hemisphere, revealed four major groups: (1) C. benthamii and C. lindleyi from central Mexico; (2) C. macrocarpa, C. guadalupensis, C. nootkatensis, C. forbesii, and C. bakeri; (3) C. goveniana, C. pigmaea, C. sargentii, C. abramsiana, C. nevadensis, C. arizonica, and C. montana (= C. arizonica var. montana); and (4) C. glabra, C. stephensonii, and C. macnabiana. This analysis supports the placement of Ch. nootkatensis into Cupressus ( C. nootkatensis). Trees identified by Wolf (1948) as C. sargentii from Santa Barbara Co., proved to be quite distinct in their RAPDs from C. sargentii populations growing north of this county. Additional field studies are being conducted to resolve the specific status of these plants. Individuals of C. forbesii showed considerable variation within and among populations, suggesting possible hybridization or micro-differentiation.