The phylogenetic position of a freshwater green alga, Aegagropila linnaei (Cladophorales, Ulvophyceae), was investigated using nuclear 18S rRNA gene sequences. This alga has usually been called Cladophora aegagropila (L.) Rabenhorst or Cladophora sauteri (Nees ex Kütz.) Kütz. Based on morphology, it was formerly classified into the section Aegagropila or into the subgenus Aegagropila, together with several marine species of the genus Cladophora. This classification is not supported by the present phylogenetic analyses in which two very distinct Cladophorales clades are recognized. Aegagropila linnaei groups together in a well‐supported clade with Cladophora sp., Pithophora sp., Chaetomorpha okamurae, Arnoldiella conchophila, Wittrockiella lyallii, and Cladophora conchopheria. Aegagropila linnaei and its closely related species share some ultrastructural and biochemical characteristics, like pyrenoid structure, carotenoid composition, and cell wall composition. Freshwater species, included in the analysis, were located in two distantly related lineages, indicating that adaptation from a marine to a freshwater habitat has happened at least twice independently in the Cladophorales.

Aim Mangroves are intertidal plants with sea-dispersed propagules, hence their population structure can offer valuable insights into the biogeographical processes driving population subdivision in coastal species. In this study, we used molecular markers and ocean circulation simulations to examine the effects of ocean currents and land masses on the genetic structure of the major mangrove species Rhizophora mucronata. Location Southeast Asia.Methods We assessed the genetic structure of 13 R. mucronata populations from continental Southeast Asia and Sumatra using 10 microsatellite loci. We first examined the relative effects of geographical distance and land mass (the Malay Peninsula) in shaping the genetic structure of R. mucronata in Southeast Asia. We then characterized the genetic structure of R. mucronata and compared it to the simulated ocean circulation patterns within our study region. ResultsDespite the low genetic diversity, significant genetic structuring was detected across R. mucronata populations. Contrary to observations on other mangrove species, genetic differentiation in R. mucronata was not found across the coasts of the Malay Peninsula, nor was it correlated with geographical distance. Instead, the most distinct genetic discontinuity was found at the boundary between the Andaman Sea and the Malacca Strait, and this can be explained by the prevailing ocean currents in this region.Main conclusions Our study presents novel evidence that the genetic structure of R. mucronata is maintained by ocean current-facilitated propagule dispersal.

In order to clarify evolutionary patterns and processes of intraspecific diversification of Primula cumifo/ia Ledeb. (Primulaceae), we analyzed intraspecific variation of the nucleotiie sequences of non-coding regions of chloroplast DNA the intergenic spacers between ImT (UGU) and the tml (UAA) B'exon, the ImL (UAA) 3'exon and ImF (GAA), and at@ and nbcL. In 20 populations of P. cumMb, 22 nucleotide substitutions and five insertions/deletions were inferred, and their genetic distances ranged from 0.001 to 0.008. Eight distinct haplotypes could be recognized and each haplotype was found to be geographically structured. Three major clades (the Northern, Hokkaido and Southern clades) were revealed in phylogenetic analyses of the haplotypes The haplotypes of the Northern clade had a wider distribution area in the populations of Mt. Rausu and Rishiri Island of eastern and northern Hokkaido in Japan, northward to Unalaska Hand in the Aleutians, and those of the Hokkaido clade were distributed in the populations of central Hokkaido and Mthvaki of the northern Honshu in Japan; in addition, those of the Southern clade were observed only in the populations of the central Honshu. It was shown that the genetic diversifications of the Southern clade were higher than those of the Northern and Hokkaido clades. Furthermore, it was shown that the topology within the Southern clade was hierarchical, and the haplotypes of the Southern populations in the clade were derivative. From these results, we concluded that the cpDNA hap lotypes of the three clades in P. cumifo/ia arose and assumed the present distribution areas through several cycles of glacial advance and retreat in the Pleistocene.

Species complexes consisting of ill-defined "species" are widely known among ferns, and their involvement with reticulate evolution is expected. Nevertheless approaches to reticulation history with DNA markers are not yet commonly adopted. We have successfully elucidated the biological status of the Vandenboschia radicans complex in East Asian islands by combining analyses of ploidy level, a cpDNA marker (rbcL), and a nuclear DNA marker (GapCp). The results based on 266 individuals collected from 174 localities throughout Japan and Taiwan suggest that complicated hybridizations have occurred involving at least three parental diploid species from within the V. radicans complex and Vandenboschia liukiuensis, which was formerly considered to be distinct from this complex. Triploids are the most common cytotype, but they show no evidence of apogamous reproduction, while all nonhybrid diploids are rare and have very limited distribution. Possible accounts of this phenomenon will be briefly discussed including the possibility of relict distribution and occasional apogamous reproduction.

Pinus species have three differently inherited genomes: paternal chloroplast, maternal mitochondrial, and biparental nuclear. Our previous study on the hybrid zones between alpine Pinus pumila and montane to subalpine P. parviflora var. pentaphylla demonstrated contrasting patterns of introgression of two cytoplasmic genomes, i.e., the paternal cpDNA flowed from P. parviflora var. pentaphylla to P. pumila, and the maternal mtDNA flowed in the reverse direction. In the present study, we developed codominant nuclear DNA markers diagnostic or mostly diagnostic for each parental species by single-strand conformation polymorphism (SSCP) of polymerase chain reaction (PCR) products, using expressed sequence tag (EST) primers of Pinus taeda. To describe the introgressive patterns of the nuclear genes, the molecular hybrid index (MHI) showing the overall proportion of alleles inferred to be derived from P. pumila was determined for each plant collected in hybrid zones on Mt. Asahidake and Mt. Higashiazuma, Japan. At Mt. Asahidake, the MHI values changed clinally according to the altitudes at which the plants were collected. However, at Mt. Higashiazuma, there was a gap in the MHI values between the plants above and below the Abies and Tsuga forest zone (alt. 1800-1900 m). This suggested that the zone plays a role in creating an effective barrier to gene flow in the hybrid zone.