Allozymic relationships of Arceuthobium campylopodum and allies in California

Abstract

Allozyme electrophoresis was used to examine genetic variation among populations of the dwarf mistletoes parasitic on Pinus ponderosa ( Arceuthobium campylopodum) and P. sabiniana, P. muricata and P. radiata ( A. occidentale). Twenty-seven populations were sampled throughout California and genotypes at nine electrophoretic loci were determined. UPGMA cluster analysis from genetic distances and distance Wagner trees indicate the coastal taxon parasitic on bishop and Monterey pine is a distinct species ( A. littorum) from populations of A. campylopodum and A. occidentale. Cluster analysis does not, however, segregate the ponderosa and digger pine dwarf mistletoes into distinct groups. In populations where both host species were parasitized, no significant genetic differentiation was noted between the two putative mistletoe taxa. The results of this allozyme analysis support the concept of a single biological species for A. campylopodum and A. occidentale.