M ferrites (M = Ni and Cu) were prepared for the CO2 decomposition reaction. The mechanisms of reduction and oxidation of M ferrites were investigated by thermogravimetric analysis and X-ray diffraction experiments. Cu ferrite showed excellent redox properties compared to those of Ni ferrite. Cu ferrite lost its oxygen atoms from the lattice by the H2 reduction at 473 K, which was 150 K lower than the temperature at which Ni ferrite did. The reduction of Cu ferrite at 1073 K formed the mixture of metallic Cu, FeO, and α-Fe, while Ni ferrite gave a Ni−Fe alloy at the same temperature. Reaction of the reduced ferrites with CO2 oxidized the ferrites by suppling oxygen atoms from CO2. The oxidation temperature of the reduced Cu ferrite was 200 K lower, and the weight recovery was faster than that of Ni ferrite. The oxidation with CO2 at 1073 K could not regenerate their original states and produced the mixture of Fe3O4 and metallic Cu and Ni. On the basis of the understanding of the Cu ferrite redox behaviors, a new mechanism for the CO2 decomposition reaction was proposed.

Polyploidy plays an important role in the speciation of Isoëtes. Increasing our knowledge about the specific origin of each polyploid or phylogenetic relationship among species has been hampered because of conserved morphological variation and scarce habitats. We present several hypotheses concerning the speciation pathways of Isoëtes species distributed in East Asia. Our hypotheses are inferred from phylogenetic relationships that were elucidated using sequences of the internal transcribed spacer regions of nuclear ribosomal DNA, a second intron of LEAFY, and chloroplast DNA trnS-psbC spacer regions. These inferred phylogenetic relationships indicated that (1) the Chinese tetraploid, I. sinensis, is closely related to I. yunguiensis; (2) the Korean endemic species, I. hallasanensis, is an autotetraploid derived from I. taiwanensis or closely related taxa; (3) the hexaploid I. coreana forms a clade and has its closest evolutionary relationships with I. taiwanensis or I. hallasanensis; and (4) the Japanese hexaploid I. japonica is closely related to I. taiwanensis-I. coreana and I. sinensis-I. yunguiensis. These results suggest that interspecific hybridization and polyploidization have played central roles in speciation of East Asian Isoëtes. Furthermore, I. taiwanensis, an endemic species in Taiwan, has been involved in at least three cases of autopolyploid or allopolyploid speciation in East Asia.

Genetic variation of nuclear ribosomal ITS (nrITS) and chloroplast DNA (cpDNA) regions was investigated in Brasenia schreberi (Cabombaceae) to assess the population structure and to infer the evolutionary relationship among 12 populations distributed in South Korea. The combined sequence of the two regions was aligned to 2,069 bp, of which 28 sites were variable. In total, 20 genotypes were identified from 240 individuals of B. schreberi. Genotype diversity (Gd) and nucleotide diversity (Pi) on Jeju Island (Gd=0.2511, Pi=0.00012) were higher than those of the mainland of South Korea (Gd=0.1358, Pi=0.00005). The relatively low level of genetic variation of the mainland populations is associated with its higher genetic differentiation (G ST =0.095 on mainland and 0.039 on Jeju Island) and human activities. Minimum spanning network analysis demonstrated that the investigated populations of B. schreberi were subdivided into two geographical groups: the mainland of South Korea and Jeju Island. In addition, analysis of molecular variation showed that a large proportion (73.55%) of genetic differentiation existed between the two regions. These results strongly suggest the presence of significant barriers to gene flow between regions. Thus, the management unit for B. schreberi should be carefully designed to avoid the potential risk that can results from the admixture of individuals from the mainland and Jeju Island regions.

No abstract

As part of an on-going effort to conserve endangered and endemic Scrophularia takesimensis (Scrophulariaceae), we analyzed its spatial distribution patterns by applying an index of dispersion, plant-to-all-plant distances, and the varying quadrat size method. Three indices --Dispersion, Morisita, and Standardized Morisita --all revealed clumping with small aggregates, and distances between aggregates were more or less regular. The asymptote level occurred at a distance of 20 to 30 m; the distance showing 90% of cumulative frequency coincided with 20 to 21 m; 95%, 24 to 25 m; and 99%, 31 to 32 m. The 20 m• 20 m and 40 rex40 m quadrats contained 25 and 40 plants, respectively. We conclude that this number of individuals and size of area are the minimum required for the conservation of this species.

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Ulleung Island is a biodiversity hot spot harboring approximately 700 species of vascular plants with high number of endemic taxa. Physocarpus insularis, one of the 41 endemic species, has an extremely restricted distribution range on the very small, geologically young oceanic island. Phylogenetic relationship of P. insularis, however, remained highly controversial whether it is conspecific with Spiraea chamaedryfolia or a distinct species in Physocarpus, making it difficult to establish necessary conservation programs. We examined comparative morphology of Physocarpus and Spiraea and reconstructed the phylogeny of the rbcL, matK, ndhF, and trnL-trnF regions from the exemplars of Rosaceae. The results strongly supported the placement of P. insularis within Spiraea. Further phylogenetic analyses of tribe Spiraeeae based on the trnL-trnF and internal transcribed spacer data showed that P. insularis is closely related to S. chamaedryfolia. Morphological analysis revealed that P. insularis differs from S. chamaedryfolia by having larger leaf blades that are subcordate or truncate at base. Results of this study suggest that P. insularis should be recognized as a distinct taxon in Spiraea and that conservation efforts on Ulleung Island should focus on protecting its natural environment to conserve evolutionary patterns and processes in addition to specific conservation programs for species in peril.

As part of the on-going effort to conserve endangered Zostera japonica Ascher. & Graebn. in Korea, we have used RAPD band patterns to analyze its genetic structure and diversity. Out of 50 primers tested, 45 formed amplified bands with its genome, including 814 polymorphic and 28 monomorphic bands. The highest number (120) was found in the population of Geoje-do; the smallest (58), in Anmyeon-do. An examination of its genetic structure with AMOVA revealed that about 50% of all variations could equally be assigned to within and between populations. The statistical value GST (index of genetic differences) was 0.49, and the average number of individuals exchanged between populations per generation (N~n) was calculated as 0.26. Although the habitats of Z. japonica in Korea are disappearing at an alarming rate, significant levels of genetic variation still exist, especially in the Geoje.do population. Therefore, any recovery strategy for this endangered species should be planned on the basis of this genetic diversity among populations.