Geographic variation in chloroplast haplotypes in the California red fir-noble fir species complex and the status of Shasta red fir

Abstract

I present the results of a molecular investigation into taxonomically unresolved issues of the California red fir – noble fir species complex. Samples were collected throughout the range of California red fir ( Abies magnifica A. Murray), from the southern Sierra Nevada to the region in northern California and southern Oregon where morphological variation has suggested it hybridizes with noble fir ( Abies procera Rehder). Two rbcL sequences were found within A. magnifica and showed perfect linkage with variation at the chloroplast trnD locus. Only populations in the region of hypothesized hybridization were polymorphic for rbcL. One haplotype is unique to A. magnifica in the southern part of its range, and the other is identical to that found in A. procera to the north, supporting a broad zone of hybridization. There was no evidence for a cryptic geographic barrier between the two species. A single A. procera tree from southwestern Washington also had the A. magnifica haplotype, suggesting that introgression from A. magnifica may be widespread. The type locality of Abies magnifica var. shastensis Lemmon was polymorphic, whereas the disjuct southern A. magnifica var. shastensis was monomorphic for rbcL. I also present corrections, based on replication, to two rbcL sequences for A. magnifica previously deposited in GenBank.