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Although homoploid hybrid speciation in plants is probably more common
than previously realized, there are few well-documented cases of homoploid
hybrid origin in conifers. We examined genetic divergence between two
currently widespread pines in northeast China, Pinus sylvestris var.
mongolica and P. densiflora, and also whether two narrowly distributed
pines in the same region, P. funebris and P. takahasii, might have
originated from the two widespread species by homoploid hybrid speciation.
Our results, based on population genetic analysis of chloroplast (cp),
mitochondrial (mt) DNA, and nuclear gene sequence variation, showed that
the two widespread species were divergent for both cp- and mtDNA
variation, and also for haplotype variation at two of eight nuclear gene
loci surveyed. Our analysis further indicated that P. sylvestris var.
mongolica and P. densiflora remained allopatric during the most severe
Quaternary glacial period that occurred in northeast China, but
subsequently exhibited rapid range expansions. Pinus funebris and P.
takahasii, were found to contain a mixture of chlorotypes and nuclear
haplotypes that distinguish P. sylvestris var. mongolica and P.
densiflora, in support of the hypothesis that they possibly originated via
homoploid hybrid speciation following secondary contact and hybridization
between P. sylvestris var. mongolica and P. densiflora.
247 views reported since publication in 2011.