Based on molecular phylogenetic evidence, phylogenetic analyses of both cpDNA and nrDNA sequences based on 76 (cp) and 77 (nr) samples representing 64 species, two subspecies, and three (cp) and two (nr) varieties of Lilium and six (cp) and five (nr) samples from Cardiocrinum, Fritillaria, and Notholirion as outgroups were used to better understand relationships within Lilium and to revise its infrageneric classification. The same individuals were used for both cpDNA and nrDNA analyses to avoid confusion caused by genetic polymorphism within a species. Nine thousand eight hundred thirty seven bp from 10 cpDNA regions and 1069 bp from the nuclear (ITS + ETS) regions were analyzed. The same twelve clades were formed in Lilium in both the chloroplast and nuclear trees (one clade of the former tree and one clade of the latter tree were not strictly formed because of low resolution). In light of the cpDNA and nrDNA trees obtained, 13 morphological characters, including a pair of marginal ridges along a central groove on the adaxial surface of the tepals were examined with attention given for the first time to the use of this character as having diagnostic value. The morphological evidence supported the twelve clades. Based on molecular and morphological evidence, a revised infrageneric classification of Lilium recognizing twelve clades as twelve sections is proposed.
Shota Sakaguchi, Atsushi Abe, Koki Nagasawa, Daiki Takahashi, Hiroaki Setoguchi, Masayuki Maki, Ryuta Kyan, Takako Nishino, Naoko Ishikawa, Shun K. Hirota, Yoshihisa Suyama, Motomi Ito
Repeated adaptation to similar environments can lead to divergence of phenotypes in different populations. Such evolutionary changes sometimes result in incongruence between morphology and molecular phylogeny, for which careful biological investigation is required. Natural phenotypic variation in rheophytic populations of the Solidago virgaurea L. complex (Asteraceae), which evolved multiple times from ancestral dryland forms in Japan, are here reported. Common garden experiments and population genetic analysis were used to evaluate the extent to which parallelly evolved rheophytes diverged in morphological, phenological and genotypic features to understand their complex evolutionary history. Significant divergence among rheophytic populations was detected in multiple traits, even in leaf morphological traits, which are similarly subjected to purifying selection by water pressure in riparian habitats. Whereas most of the variation were attributed to differences between specific pairs of populations, flowering phenology showed latitudinal variation, which likely evolved along a large-scale environmental cline. Multivariate analysis revealed that at least the population on Okinawa Isl., at the edge of the range of the species, is phenotypically distinguishable from rheophytic populations on the main islands. Phylogenetic analysis also suggested that the Okinawan rheophytes are genetically isolated from parapatric dryland populations. Based on the evidence, the Okinawan rheophytic plants are recognized as specifically distinct and are described as Solidago yambaruensis S. Sakaguchi & Mot. Ito.
Hiroshi Noda, Jun Yamashita, Shizuka Fuse, Rachun Pooma, Manop Poopath, Hiroshi Tobe, Minoru N. Tamura
Dioscorea (Dioscoreaceae) is a diverse genus of more than 600 species. To understand relationships and character evolution within the genus, 273 samples from 183 species (including 28 newly sequenced species) based on four cpDNA regions were analyzed phylogenetically. The phylogenetic tree obtained comprised eleven well-supported major clades, most of which further consisted of more than two subclades. Comparisons with previously proposed infrageneric taxa (23 to 58 sections and associated ‘genera’) showed that some sections/‘genera’ are monophyletic and others polyphyletic. As in previous studies, ‘D. sect. Stenophora’ was sister to the rest of the genus. The present analyses of character state distribution on the tree confirmed that ‘D. sect. Stenophora’ is characterized by having rhizomes, monosulcate pollen and a diploid chromosome number based on x = 10 (plesiomorphies), whereas the rest of the genus has tubers and bisulcate pollen (apomorphies), but is diverse in regard to chromosome number, stem twining direction, fruit types and seed wing morphology. Based on molecular and morphological evidence, two subgenera, Dioscorea (= ‘D. sect. Stenophora’) and Helmia, are proposed. For subgenus Helmia, a revision of the infrageneric classification, especially for the species in the Old World, is needed.
Based on new collections of Machilus from three locations in Cambodia, six species including four new species are recognized: Machilus angustifolia sp. nov., M. bokorensis Yahara & Tagane, M. brevipaniculata Yahara & Tagane, M. cambodiana sp. nov., M. elephanti sp. nov., and M. seimensis sp. nov. Those species are characterized by DNA sequences of rbcL, matK and ITS and vegetative traits of leaves, young twigs and terminal buds. Among four species collected from the same locality, M. angustifolia and M. brevipaniculata have naked terminal buds, but are distinguished by leaf shape and are not close in the ITS tree; M. bokorensis and M. elephanti have scaly terminal buds but are distinguished by the size and morphology of their terminal buds and are not clustered together in the ITS tree. Two additional species differ in their terminal buds, naked in M. cambodiana and scaly in M. seimensis, and are not clustered together in the ITS tree. Four new species are described by comparison with related species and their conservation status is qualified. A new name M. kerrii comb. nov., based on Phoebe kerrii Gamble, is made.