Abstract Detail

Systematics Section / ASPT

Lang, Ping [1], Dane, Fenny [1].

Phylogeny and biogeography of Castanea (Fagaceae) based o­n chloroplast sequence data.

Sequencing analysis of five chloroplast DNA regions (trnT-L-F, rpl16 intron, partial ndhF gene and 3’ flanking region, intergenic spacer ycf6-psbM and orf62-trnGM) were conducted to infer phylogeny and biogeographical history of the genus Castanea (Fagaceae). The length of the total sequenced cpDNA regions comprises over 7.5kb per taxon, which represents 4.8% of the chloroplast genome of 155kb. The genus Castanea is supported as a monophyletic clade, and section Eucastanon is a paraphyletic group. C. crenata, the Japanese chestnut, was shown to represent an early divergence in the genus, forming a sister group to remaining members of the genus. Three Chinese species formed a well-supported, sister clade to the North American and European clade. The North America species are supported as a clade with C. pumila var. ozarkensis as the basal lineage, which is sister to the group of C. pumila var. pumila and C. dentata. Allegheny (var. pumila) and Ozark chinkapin (var. ozarkensis) have been considered as two varieties of o­ne species C. pumila. However, considering all the sequence data, the two varieties of C. pumila should be raised to species level. The cpDNA pattern was geographically structured. A total of 13 haplotypes were detected in all species of Castanea. Higher levels of cpDNA diversity were found in Asia as compared to North America and Europe. It is hypothesized that Castanea originated in Eastern Asia and speciation is assumed to be by vicariance separating the Japanese species, followed by dispersal from eastern Asia to Europe and o­nto North America and vicariance through separation of land masses. Morphological evolution of o­ne nut per bur might have occurred independently o­n two continents and possibly at least 3 times in the genus.

1 - Auburn University, Horticulture, 101 Funchess Hall, Auburn, Alabama, 36849

Keywords:
Castanea
chestnut
biogeography
chloroplast DNA
phylogeny.

Presentation Type: Poster
Session: 32-101
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:574