• Journal of Elementary Mathematics Education in Korea
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• 제16권3호
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• pp.321-336
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• 2012

Cognitive subject imposes structures on an object to shape it into a structured thing. Structures that the subject imposes on an object in a given problem context can be diverse horizontally and vertically. In view of the horizontal diversity of structure, problem-solving activities focusing on various structures may enrich the present problem-solving education which emphasizes applying and comparing a couple of problem-solving strategies. Finding an algebraic formula for a figural pattern should be regarded as a new starting point of searching for more various structures. In view of the vertical diversity of structure, it should be aware that students may see different structures from the structure that their teacher expect them to see. The vertical diversity of structure enables us to provide students with experience of progress.

• Journal of Life Science
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• 제12권1호
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• pp.27-32
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• 2002

Enzyme electrophoresis was used to estimate genetic diversity and population structure of maize, Zea mays L. (Graminales) in Korea. In nine populations, fourteen of the 24 loci (58.3 %) showed detectable polymorphism. Genetic diversity (0.205) was higher than average values for species with similar life history traits. Although our data are relatively small and the landraces not direct ancestors of cultivar, apparently the domestication process has eroded the levels of genetic variation of maize. The recent cultivars were found to have fewer alleles per locus (1.42 vs. 1.56), fewer alleles per polymorphic locus (2.27 vs. 2.33), lower percent polymorphic locus (33.3% vs. 41.7%), and lower diversity (0.159 vs. 0.185) than landraces. These genetic diversity parameters indicated that the cultivar populations were genetically depauperate relative to landlaces. The GST value of nine populations was 0.239. Nearly 76% of the total genetic diversity in Zea mays was apportioned within populations. The indirect estimate of gene new based on mean GST was moderate (Nm=0.80).

• Korean Journal of Environmental Biology
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• 제29권4호
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• pp.345-352
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• 2011

We investigated 12 plots using Herles' diversity of structure feature calculation method, which is based on the Shannon-Weaver-Index for estimation of species diversity. This study sought to facilitate a more systematic understanding of the structure of the forest stands in the Korean fir natural forest in Naeseorak. Although the change in the forest structure is dependent on the change in phase, factors of the natural forest were confirmed by associating individual structure features. As shown in the results of diversity of structure features, the diversity of the structure of the fir tree natural forest in Naeseorak was relatively low. The association between species diversity and overall factors (diversity) related with the change in the structure was found to be weak. The association between the number of trees and the diversity of forest structure stands was moderate, showing that the higher the number of trees, the less diverse the forest structure is. In most of the investigated plots, stem volume and volume of dead tree were associated with the height of natural regeneration, but these were not associated with other factors. Height of natural regeneration was found to be correlated to stand density, crown area and crown class, whereas tree height and BHD did not have any association with other factors. Overall, the results of the investigation are helpful in understanding the change in the structure of Korean fir natural forest. Further investigation with more plots is required.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제58권4호
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• pp.336-346
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• 2013

Amaranth (Amaranthus sp. L.) is an important group of plants that includes grain, vegetable, and ornamental types. Centers of diversity for Amaranths are Central and South America, India, and South East Asia, with secondary centers of diversity in West and East Africa. The present study was performed to determine the genetic diversity and population structure of 75 amaranth accessions: 65 from South America and 10 from South Asia as controls using 14 SSR markers. Ninety-nine alleles were detected at an average of seven alleles per SSR locus. Model-based structure analysis revealed the presence of two subpopulations and 3 admixtures, which was consistent with clustering based on the genetic distance. The average major allele frequency and polymorphic information content (PIC) were 0.42 and 0.39, respectively. According to the model-based structure analysis based on genetic distance, 75 accessions (96%) were classified into two clusters, and only three accessions (4%) were admixtures. Cluster 1 had a higher allele number and PIC values than Cluster 2. Model-based structure analysis revealed the presence of two subpopulations and three admixtures in the 75 accessions. The results of this study provide effective information for future germplasm conservation and improvement programs in Amaranthus.

• Journal of Korean Society of Forest Science
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• 제86권2호
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• pp.158-166
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• 1997

This study presents the method to quantify the stand structure diversity or homogeneity. Gadow's dbh differentiation(Durchmesserdifferenzierung) is introduced which quantifies the horizontal stand structure by the ratio of the dbh between subject tree and neighbour trees. And new stand structure diversity index based on Lorenz curve, which is made by ratio of tree number and basal area or volume by dbh class, is presented. The horizontal stand structure index based on Lorenz curve has a value from 0 to 1 as Gadow's index, and approximates to 1 if the stand structure has high diversity. In the comparative analysis for performance, the new stand structure index based on Lorenz curve is considered to compare with the Gadow's index for describing the stand structure.

• Journal of Life Science
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• 제18권2호
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• pp.175-179
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• 2008

Cornus controversa is a long-lived woody species mostly distributed in East Asia. Random amplified polymorphic DNA (RAPD) markers were used to investigate the genetic diversity and population structure of Korean populations of this species. A high level of genetic variation was found in seven populations of C. controversa. The mean genetic diversity (H) was 0.222 across populations, varying from 0.200 to 0.238. Eighty of the 93 loci (86.0%) showed detectable polymorphism in at least one population. Total genetic diversity values ($H_T$) varied between 0.192 and 0.231, giving an average overall polymorphic loci of 0.212. The interlocus variation of genetic diversity within populations ($H_S$) was high (0.167). Mean of genetic diversity in C. controversa was higher than average values for species with similar life history traits. The sexual reproduction, perennial habitat, and longevity are proposed as possible factors contributing to high genetic diversity. On a per locus basis, the proportion of total genetic variation due to differences among populations ($G_{ST}$) ranged from 0.169 to 0.278 with a mean of 0.216, indicating that about 21.6% of the total genetic variation was among populations. An indirect estimate of the number of migrants per generation (Nm=1.893) indicated that gene flow was extensive among Korean populations of C. controversa.

• Journal of Forest and Environmental Science
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• 제39권1호
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• pp.1-12
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• 2023

To understand the health conditions and growth patterns of forest estate for environmental resilience and climate change mitigation, assessment of structure and species diversity is paramount. This study aimed at assessing the structure, alpha, and beta diversities of tree species in three ecological zones in Taraba, Nigeria for management purposes. In recent time, no research has been reported on the structure and beta diversity of the study areas. A systematic sampling design was used for data collection. Five sample plots of 50×50 m were laid in each of the six natural forest areas. The result showed a mean DBH (42.5 cm) and a tree height (15.0 m) from the forests. The forests have a structure of an inverse "J-shape," which is typical of natural forests in the tropics. The southern Guinea savanna zone had the highest mean Shannon-Weiner diversity index (2.8). The least beta diversity index (0.02) was between Baissa and Jen Gininya forest areas. Baissa and Bakin Dutse Protected Forest Areas (PFAs) contained 76.5% of the tree species. There is a high chance of all tree species to be found in these 2 forest areas. Proximity to a location influences how similar two tree species are, according to the least beta diversity index (0.02) recorded. The Federal Government's method of management for the forest, known as Gashaka Gumti National Park, may be responsible for the high beta diversity index in the Montane ecozone. Therefore, it should be strongly encouraged to practice strict oversight of natural areas, as their contributions to reducing climate change in Taraba State, Nigeria, cannot be overstated.

• Journal of Microbiology and Biotechnology
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• 제31권7호
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• pp.978-989
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• 2021

Allyl isothiocyanate (AITC), as a fumigant, plays an important role in soil control of nematodes, soil-borne pathogens, and weeds, but its effects on soil microorganisms are unclear. In this study, the effects of AITC on microbial diversity and community composition of Capsicum annuum L. soil were investigated through Illumina high-throughput sequencing. The results showed that microbial diversity and community structure were significantly influenced by AITC. AITC reduced the diversity of soil bacteria, stimulated the diversity of the soil fungal community, and significantly changed the structure of fungal community. AITC decreased the relative abundance of dominant bacteria Planctomycetes, Acinetobacter, Pseudodeganella, and RB41, but increased that of Lysobacter, Sphingomonas, Pseudomonas, Luteimonas, Pseudoxanthomonas, and Bacillus at the genera level, while for fungi, Trichoderma, Neurospora, and Lasiodiplodia decreased significantly and Aspergillus, Cladosporium, Fusarium, Penicillium, and Saccharomyces were higher than the control. The correlation analysis suggested cellulase had a significant correlation with fungal operational taxonomic units and there was a significant correlation between cellulase and fungal diversity, while catalase, cellulose, sucrase, and urease were the major contributors in the shift of the community structure. Our results will provide useful information for the use of AITC in the assessment of environmental and ecological security.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제2권2호
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• pp.120-128
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• 2021

The objective of this study was to analyze the genotype of black-spotted pond frog (Pelophylax nigromaculatus) using seven microsatellite loci to quantify its genetic diversity and population structure throughout the spatial scale of basins of Han, Geum, Yeongsan, and Nakdong Rivers in South Korea. Genetic diversities in these four areas were compared using diversity index and inbreeding coefficient obtained from the number and frequency of alleles as well as heterozygosity. Additionally, the population structure was confirmed with population differentiation, Nei's genetic distance, multivariate analysis, and Bayesian clustering analysis. Interestingly, a negative genetic diversity pattern was observed in the Han River basin, indicating possible recent habitat disturbances or population declines. In contrast, a positive genetic diversity pattern was found for the population in the Nakdong River basin that had remained the most stable. Results of population structure suggested that populations of black-spotted pond frogs distributed in these four river basins were genetically independent. In particular, the population of the Nakdong River basin had the greatest genetic distance, indicating that it might have originated from an independent population. These results support the use of genetics in addition to designations strictly based on geographic stream areas to define the spatial scale of populations for management and conservation practices.

• Journal of Species Research
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• 제7권4호
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• pp.354-362
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• 2018

Population genetic assessment is essential for the conservation and management of endangered and rare plants. Neofinetia falcata is endangered epiphyte orchid and protected by law in Korea. In Korea, this species is only found on islands in the South Sea of Korea (including Jeju-do) and the southern coast of the Korean Peninsula. We developed nine microsatellite makers to assess the genetic diversity and population genetic structure of three populations of N. falcata. The genetic diversity at the species level was low, which can be attributed to inbreeding or fragmentation into small, isolated populations. A recent bottleneck was detected in one population, likely due to overcollection. N. falcata exhibited moderated levels of differentiation among populations, with the three populations were divided into two clusters based on genetic structure. The genetic diversity and structure of N. falcata are affected by restricted gene flow by pollen or seeds due to isolation and geographic distance. Strategies for in situ and ex situ conservation of this species are been proposed based on the results of our study.