• Journal of Environmental Science International
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• v.3 no.4
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• pp.297-304
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• 1994

The genetic variabilities of second chromosomes concealed Sasang natural and experimental populations of Drosophila melanogaster have been analyzed. The experimental population was composed of D. melanognter which had the lethal-free second chromosome collected from Sasang natural population in 1982. The results were as follow; The mean frequencies of deleterious genes were estimated % be 33.33% in Sasang natural population and 31.72% in experimental population. The allelism rates in lethal genes isolated from the natural and experimental populations were calculated to be about 0.95% and 12.28%, respectively. The allelism rates between lethal genes isolated from the natural population and those of the experimental population were calculated to be about 0.01%. The mean values of elimination by frequencies of deleterious genes and allelism rates were 0.0011 in the natural population and 0.0124 in the experimental population. The frequencies of phenotypic sterility of males in the natural and experimental populations were estimated to be 1.49% and 1.36%, respectively. The frequencies of genotypic sterility of females and males were estimated to be 0.90% and 1.80% in the natural population, and that of males was 2.38% in the experimental population.

• Journal of Korean Society of Rural Planning
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• v.14 no.4
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• pp.1-9
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• 2008

Many urban people are attracted to the recreational opportunities and attractions of rural areas, such as beautiful scenery, lakes, mountains, forests, and resorts. Furthermore, rural development planning increasingly emphasizes the integration of resource extractive industries with non-market-based recreational and amenity values. This article outlines a method to estimate an amenity level of rural areas such as natural amenities index and shows the relation of the natural amenity and population growth. The results revealed that natural amenity classifying each region can be explained with geographical characteristics, temperature-humidity, and sunshine duration time. In analysis with population, natural amenity does not exactly explain that but can be one of the important factor of population change.

• Journal of Korean Society of Rural Planning
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• v.29 no.3
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• pp.15-24
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• 2023

The sense of crisis regarding regional extinction due to low birth rates and an aging population is expanding. Generally, the local extinction index is used to analyze local extinction. However, it is challenging to diagnose the actual situation of village extinction risk in rural areas, even though the regional extinction index can be analyzed in units such as Si-Gun-Gu and Eup-Myeon-Dong. This difficulty arises because the regional extinction index solely relies on natural population growth indicators (elderly population and female population aged 20-39). Therefore, the purpose of this study is to develop a village extinction index that can identify the disappearance of rural villages. Additionally, the aim is to apply the developed indicators to the village (administrative ri) spatial unit. The existing regional extinction index used only mortality-related indicators as factors for natural population decline and fertility-related indicators as factors for natural population growth. However, the developed village extinction index included not only the factors of natural population change but also incorporated social population growth factors and factors related to the pace of village extinction. This is the key difference between the developed village extinction index and the existing regional extinction index. In this study, the indicators of "total population," "number of young women aged 20-44," "number of elderly population aged 70 or older," and "number of incoming population" were selected to develop a village extinction index. The village extinction index was developed by incorporating both natural population growth indicators and social population growth indicators. The developed village extinction index was applied to administrative villages. This research is expected to provide a more accurate understanding of the current state of rural villages facing extinction.

• Journal of Aquaculture
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• v.16 no.2
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• pp.69-75
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• 2003

Genetic variability and population structure of 11 natural ayu, Plecoglossus altivelis populations and one hatchery stock were assessed by starch gel electrophoretic analysis with 10 enzyme coding loci. Three loci were polymorphic (lower than 0.95 in major allele frequency) in natural populations,2 loci in hatchery stock. The average number of alleles per locus was 1.38. Observed heterozygosities ranged from 0.0235 to 0.088 (0.055 on the average) in natural population while 0.0925 in hatchery stock. The genetic distance among natural populations measured 0.000047-0.005407 and no significant differentiation was observed among them. On the other hand, a signifcant genetic distance was found between natural populations and the hatchery stock with measuring 0.002032-0.O08605. The results in this study suggest that the hatchery stock has diverged from natural populations, and also that careful to maintain sustainable and effective population size (parents number) should be made.

• Development and Reproduction
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• v.24 no.4
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• pp.327-335
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• 2020

Genomic DNA (gDNA) extracted from two populations of natural and cultured river pufferfish (Takifugu obscurus) was amplified by polymerase chain reaction (PCR). The complexity of the fragments derived from the two locations varied dramatically. The genetic distances (GDs) between individuals numbered 15 and 12 in the cultured population was 0.053, which was the lowest acknowledged. The oligonucleotide primer OPC-11 identified 88 unique loci shared within each population reflecting the natural population. The OPC-05 primer identified 44 loci shared by the two populations. The average band-sharing (BS) values of individuals in the natural population (0.683±0.014) were lower than in those derived from the cultured population (0.759±0.009) (p<0.05). The shortest GD demonstrating a significant molecular difference was found between the cultured individuals # 15 and # 12 (GD=0.053). Individual # 02 of the natural population was most distantly related to cultured individual # 22 (GD=0.827). A cluster tree was built using the unweighted pair group method with arithmetic mean (UPGMA) Euclidean GD analysis based on a total of 578 various fragments derived from five primers in the two populations. Obvious markers identified in this study represent the genetic structure, species security, and proliferation of river pufferfish in the rivers of the Korean peninsula.

• Journal of Environmental Science International
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• v.8 no.5
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• pp.587-592
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• 1999

The purpose of this study was to identify the controlling factors to construct tidal flat ecosystems having similar characteristics as natural ones. We transplanted the soil in a constructed tidal flat to a natural one and vice versa. Parameters monitored after these transplantations were silt content, organic matter, bacterial population and oxidation-reduction potential. Moreover, the relationship among silt content, organic matter and bacterial population was investigated by laboratory column experiment. The silt content, organic matter, bacterial population and vertical profile of oxidation-reduction potential in the soil transplanted from the constructed tidal flat to the natural one changed to similar values to those in the natural one. On the contrary, all the parameters for the soil transplanted from the natural tidal flat to the constructed one changed to similar values as those in the constructed one. The silt contents in thses two transplanted solis were in proportion to the organic carbon contents and bacterial population. Similarly, the bacterial population in laboratory column experiment increased with the increase in silt and organic matter contents. It seemed to be important to select a place to enhance accumulative of silt and/or to maintain the silt content by hydrodynamic control of seawater in order to construct a tidal flat having similar characteristics as natural one.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.8 no.1
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• pp.1-13
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• 1972

Yellow croacker, Tseudociaena manchurica Jordan et Thompson in the Yellow Sea and East China Sea are subjected to be caught by trawl nets throughout the year. First indices of population size in every period 8re calculated. Considering present status of the yellow croacker fishery and ecology of the fish, mathematical models must have been established in order to determine catchability coefficient, natural m ortali ty, fishing mortality, recrui ting coefficient of the fish ing ground, and dispersion coefficienl from the fishing ground. The results an, summmarized as follows: Catchabil i ty coefficient $(C) = 2. 2628 {\times} 10^{-5}$ Natural mortality (M)=0.3293 Population for lhe first half season(July 1st to the following January 3lst) Initial population = 14, 621 $/\frac{M}{T}$ Recruitment =45, 597 $/\frac{M}{T}$ Natural mortality = 8, 660 $/\frac{M}{T}$ Final population =42, 970 $/\frac{M}{T}$ Population for the latter 1131f scason(February 1st to June 30th) Initial population = 69, 170 $/\frac{M}{T}$ Dispersion =51, 688 $/\frac{M}{T}$ Natural mortality = 6, 082 $/\frac{M}{T}$ Final population = 1, 802 $/\frac{M}{T}$.

• Journal of Life Science
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• v.13 no.3
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• pp.252-257
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• 2003

The genetic variabilities of second chromosomes of Drosophila melanogaster concealed in Busan natural and experimental populations have been analyzed by the Cy//Pm method. The experimental population was composed of D. melanogaster which had the lethal-free second chromosome, collected Sasang natural population in 1982. The frequencies of deleterious genes were estimated to be 14.3∼25.4% in Busan natural population and 26.5∼27.2% in experimental population. The allelism rates in lethal genes isolated from the natural and experimental populations were calculated to be about 0.76% and 9.76∼14.17%, respectively. The value of elimination by the frequencies of deleterious genes and allelism rate was 0.0106and the effective population size estimated to be about 430 flies at the 6570 days population.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.745-751
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• 2015

The ecological characteristics of Silvetia siliquosa, an endangered brown alga, were investigated from January to December 2013 in Jindo, South Korea. The S. siliquosa population formed widespread patches on natural rock. Receptacles were observed from March to August when seawater temperatures ranged from 8-26℃. A maturation peak was detected in June, when seawater temperatures were 23.4℃. After embryo release, the alga bleached and only the discoidal holdfast remained after August. Developmental initiation of the thallus occurred at temperatures above 8℃, and receptacle formation required approximately 196 degree-days. This is the first study to examine a S. siliquosa population throughout the entire year in a natural habitat.

• Journal of Environmental Science International
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• v.5 no.1
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• pp.1-6
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• 1996

The genetic variabilities of second chromosomes of Drosophila melanogaster concealed in On-yang natural Population have been analyzed by the Cy/Pm method and an allelism test during two years(1993-1994). The mean frequencies of deleterious(lethal and semilethal) genes in On-yang natural population were estimated to be 23.97% in 1993 and 27.15% in 1994, respectively. The allelism rates between lethal genes in the population were 0.654%(1993) and 1.429%(1994). The mean values of elimination by frequencies of deleterious genes and allelism rates were 0.0004(1993) and 0.0010(1994), respectively. The frequencies of phenotypic sterility of males in 1994 were estimated to be 1.95%, and thoses of genotypic sterility of females and males were estimated to be 1.54% and 2.31%, respectively.