Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different...Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different feeding rates of 2%,3%and 4%had no significant effects on the growth of M.salmoides.Therefore,before the individual weight of 50 g,the fish could be fed with a feeding rate of 4%,which could be gradually decreased to 2%in the later period.Under the condition of relatively fixed feeding rate,different feeding frequencies had an impact on the growth of M.salmoides.Under the conditions of suitable water temperature,it is reasonable to feed twice daily.The experimental fish fed for 5 d and then deprived of feed for 1 d showed fully compensatory growth,and there were no significant differences in weight gain rate,daily weight gain and specific growth rate compared with the continuous feeding group(P>0.05).Therefore,according to the feeding conditions of fish in the breeding process,stopping feeding for 1 d every 5 d could save feed and labor and improve breeding efficiency.展开更多
Urbanization brings new selection pressures to wildlife living in cities,and changes in the life-history traits of urban species can reflect their responses to such pressures.To date,most of the studies investigating ...Urbanization brings new selection pressures to wildlife living in cities,and changes in the life-history traits of urban species can reflect their responses to such pressures.To date,most of the studies investigating the impacts of urbanization on avian life-history traits are conducted in Europe and North America,while such studies are often lacking in quickly developing countries in Asia(e.g.,China).In this study,we examined the variations in reproductive life-history traits of Chinese Bulbuls(Pycnonotus sinensis)along the urbanization gradient in Hangzhou,China.We detected 234 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013.We collected data on seven life-history traits(laying date,incubation period,nestling period,clutch size,egg volume,hatching success rate,and fledging success rate).We used infrared cameras to record the number of feedings per hour as the measure of food resources for the nestlings.We measured nest predation pressure by monitoring 148 natural breeding nests during breeding seasons and 54 artificial nests immediately after breeding seasons.We then calculated the urbanization synthetic index(USI)as a measure of the level of urbanization and examined its relationship with the seven life-history traits.We found that Chinese Bulbuls laid eggs significantly earlier with increasing USI.However,the other six life-history traits did not vary significantly with the USI.Moreover,the feeding frequency of chicks increased significantly with the USI,but the nest predation pressure of Chinese Bulbuls decreased significantly with the USI.Increased food resources and reduced nest predation pressure in cities may lead to earlier laying date of Chinese Bulbuls.Further study should test whether the earlier laying date of Chinese Bulbuls is the result of phenotypic plasticity or genetic change.展开更多
基金Supported by Key R&D Program of Hubei Province(2022BBA0058)。
文摘Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different feeding rates of 2%,3%and 4%had no significant effects on the growth of M.salmoides.Therefore,before the individual weight of 50 g,the fish could be fed with a feeding rate of 4%,which could be gradually decreased to 2%in the later period.Under the condition of relatively fixed feeding rate,different feeding frequencies had an impact on the growth of M.salmoides.Under the conditions of suitable water temperature,it is reasonable to feed twice daily.The experimental fish fed for 5 d and then deprived of feed for 1 d showed fully compensatory growth,and there were no significant differences in weight gain rate,daily weight gain and specific growth rate compared with the continuous feeding group(P>0.05).Therefore,according to the feeding conditions of fish in the breeding process,stopping feeding for 1 d every 5 d could save feed and labor and improve breeding efficiency.
基金supported by the National Natural Science Foundation of China(32271743,31971545,31071908)。
文摘Urbanization brings new selection pressures to wildlife living in cities,and changes in the life-history traits of urban species can reflect their responses to such pressures.To date,most of the studies investigating the impacts of urbanization on avian life-history traits are conducted in Europe and North America,while such studies are often lacking in quickly developing countries in Asia(e.g.,China).In this study,we examined the variations in reproductive life-history traits of Chinese Bulbuls(Pycnonotus sinensis)along the urbanization gradient in Hangzhou,China.We detected 234 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013.We collected data on seven life-history traits(laying date,incubation period,nestling period,clutch size,egg volume,hatching success rate,and fledging success rate).We used infrared cameras to record the number of feedings per hour as the measure of food resources for the nestlings.We measured nest predation pressure by monitoring 148 natural breeding nests during breeding seasons and 54 artificial nests immediately after breeding seasons.We then calculated the urbanization synthetic index(USI)as a measure of the level of urbanization and examined its relationship with the seven life-history traits.We found that Chinese Bulbuls laid eggs significantly earlier with increasing USI.However,the other six life-history traits did not vary significantly with the USI.Moreover,the feeding frequency of chicks increased significantly with the USI,but the nest predation pressure of Chinese Bulbuls decreased significantly with the USI.Increased food resources and reduced nest predation pressure in cities may lead to earlier laying date of Chinese Bulbuls.Further study should test whether the earlier laying date of Chinese Bulbuls is the result of phenotypic plasticity or genetic change.
