In order to elucidate the state of diseases, especially viral diseases, and to prevent viral diseases from occurring in olive flounder hatcheries, a range of studies, including epidemiological study, were performed fr...In order to elucidate the state of diseases, especially viral diseases, and to prevent viral diseases from occurring in olive flounder hatcheries, a range of studies, including epidemiological study, were performed from 1997 to 2003. The location of the hatcheries investigated includes several representative sites in the east （Kangnung, Uljin, Pohang, Yangsan, Ulsan, Pusan）, south （Wando, Changheung, Goheung, Yeosu, Namhae, Tongyeong, Geoje, Jeju） and west （Seosan, Kunsan, Gochang, Yeongkwang, Mokpo, Chindo） costal areas of the Korea Peninsula. A total of 2000 cases have been examined in 7 years, in which mortality caused by viral agents accounts for 22%, or 446 cases. Mortalities associated with viral infection considerably increased from 14% in 1997 to 27% in 2003. A variety of viral diseases were observed, and the occurrences of viral epidermal hyperplasia, viral ascites and viral deformity, viral nervous necrosis, and hirame rhabdoviral disease are 14%, 51%, 25%, and 8% respectively. By investigating the viral infection of broodstock flounder, the infection rate of marine birnavirus （MABV） in hatcheries was identified to be approximately 30%, therefore, it is highly necessary to acquire and keep non-infected broodstock fishes.展开更多
Understanding the occurrence of multiple distinct phenotypes in a population of a species,i.e.,polymorphism,is one of the challenges encountered in evolutionary biology.Egg color polymorphism in birds is one example o...Understanding the occurrence of multiple distinct phenotypes in a population of a species,i.e.,polymorphism,is one of the challenges encountered in evolutionary biology.Egg color polymorphism in birds is one example of morphological polymorphism and disruptive selection has been proposed as a hypothetical mechanism to explain its occurrence.We studied how polymorphic egg colors(immaculate blue and white) occur in Korean populations of the Vinous-throated Parrotbill(Paradoxornis webbianus).Egg color ratios(the proportion of nests with blue eggs in a population) were monitored over a large spatial scale and egg colors were quanti ed using a spectrophotometer.We found egg color ratios to vary spatially among populations.Interestingly,there was a latitudinal morph-ratio cline in egg color ratios.e proportion of nests with blue eggs increased considerably with the latitude declined towards the southern part of the Korean peninsula.ere were some quantitative variations in egg colors among populations.However,the pattern of variations was not consistent with those of the population egg color ratios.Based on these results,we discuss a potential scenario for the evolution of egg color polymorphism in the Vinous-throated Parrotbill.展开更多
文摘In order to elucidate the state of diseases, especially viral diseases, and to prevent viral diseases from occurring in olive flounder hatcheries, a range of studies, including epidemiological study, were performed from 1997 to 2003. The location of the hatcheries investigated includes several representative sites in the east （Kangnung, Uljin, Pohang, Yangsan, Ulsan, Pusan）, south （Wando, Changheung, Goheung, Yeosu, Namhae, Tongyeong, Geoje, Jeju） and west （Seosan, Kunsan, Gochang, Yeongkwang, Mokpo, Chindo） costal areas of the Korea Peninsula. A total of 2000 cases have been examined in 7 years, in which mortality caused by viral agents accounts for 22%, or 446 cases. Mortalities associated with viral infection considerably increased from 14% in 1997 to 27% in 2003. A variety of viral diseases were observed, and the occurrences of viral epidermal hyperplasia, viral ascites and viral deformity, viral nervous necrosis, and hirame rhabdoviral disease are 14%, 51%, 25%, and 8% respectively. By investigating the viral infection of broodstock flounder, the infection rate of marine birnavirus （MABV） in hatcheries was identified to be approximately 30%, therefore, it is highly necessary to acquire and keep non-infected broodstock fishes.
文摘Understanding the occurrence of multiple distinct phenotypes in a population of a species,i.e.,polymorphism,is one of the challenges encountered in evolutionary biology.Egg color polymorphism in birds is one example of morphological polymorphism and disruptive selection has been proposed as a hypothetical mechanism to explain its occurrence.We studied how polymorphic egg colors(immaculate blue and white) occur in Korean populations of the Vinous-throated Parrotbill(Paradoxornis webbianus).Egg color ratios(the proportion of nests with blue eggs in a population) were monitored over a large spatial scale and egg colors were quanti ed using a spectrophotometer.We found egg color ratios to vary spatially among populations.Interestingly,there was a latitudinal morph-ratio cline in egg color ratios.e proportion of nests with blue eggs increased considerably with the latitude declined towards the southern part of the Korean peninsula.ere were some quantitative variations in egg colors among populations.However,the pattern of variations was not consistent with those of the population egg color ratios.Based on these results,we discuss a potential scenario for the evolution of egg color polymorphism in the Vinous-throated Parrotbill.
