HYBRIDIZATION AND PARENTAGE OF DENDROCHILUM ACUIFERUM (Orchidaceae) INFERRED IN A PHYLOGENETIC CONTEXT USING NUCLEAR AND CHLOROPLAST DNA SEQUENCE DATA
BARKMAN, T.J., SIMPSON, B.B.
Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008 Tel #. (269) 387-5610; fax # (269) 387-5609 E-mail address email@example.com
In this paper, molecular phylogenetic analyses were used to investigate
a putative hybrid origin for Dendrochilum acuiferum, a species
endemic to Mount Kinabalu, Sabah, Malaysia. Phylogenetic analyses of
the plastid (pt) accD-psaI intergenic spacer region and a unique shared
117 bp indel indicate that D. grandiflorum and D. acuiferum
are closely related. Direct sequencing of PCR products from the ITS
1 and 2 of the nuclear ribosomal repeat region revealed single site
nucleotide polymorphisms in D. acuiferum that were additive between
two hypothesized parents in addition to other sampled species. Dendrochilum
acuiferum within-individual cloned ITS allelic sequence variants
were analyzed in a phylogenetic context to determine the relative support
for a hybrid (biphyletic) origin versus a nonhybrid (monophyletic) origin
of the alleles. Because there was a significantly higher level of support
for a hybrid origin of the alleles (P < 0.05), we subsequently compared
likelihood scores for multiple parent pairs that could have hybridized.
Although ptDNA evidence suggests Dendrochilum grandiflorum was
the most likely maternal parent of D. acuiferum, ITS results
are ambiguous about paternity because the phylogenetic results support
D. grandiflorum + D. stachyodes and D. grandiflorum
+ D. kamborangense as equally likely parents of D. acuiferum.
In addition, two other parent pairs could not be rejected (P > 0.05).
D. grandiflorum (Left), D. acuiferum (Center), D. stachyodes (Right)