Isozyme variation in Pinusmonticola

Abstract

Listen

Translate article

Seeds from 28 stands representing most of the range of Pinusmonticola Dougl. were analyzed for electrophoretically demonstrable variation in 10 proteins encoded by 12 genetic loci. On the average, 65% of the loci per stand were polymorphic, and expected heterozygosity of offspring was 18%. The populations could be assigned to two geographic groups, a broad northern one and a rather restricted southern one. The southern group consisted of populations from the Sierra Nevada and southern Cascade Mountains in northern California and from the Warner Mountains in south-central Oregon. These southern populations were similar to each other but all differed from those of the northern group in allelic frequency patterns for several isoenzymes. Across the northern part of the species' distribution (British Columbia, Washington, northern Oregon, Idaho, and Montana) differences among stands were minor and essentially random. Collections from stands in the central and southern Oregon Cascades and the Siskiyou Mountains of northwestern California were more nearly like the northern stands but exhibited some characteristics indicative of a transition area between the Sierra and northern types.