Background： Understanding the changes in population dynamics, including demographics, distribution and threats is essential for species status assessing.The endangered Green Peafowl （Povo muticus） has experienced s...Background： Understanding the changes in population dynamics, including demographics, distribution and threats is essential for species status assessing.The endangered Green Peafowl （Povo muticus） has experienced sharp population declines and d stribution range diminishing both in China and Southeast Asia. Field population surveys have not been conducted in China since the 1990s, which hindered conservation planning and decision-making.Methods： With interview and line transects methods, we figured out the population and distribution changes of Green Peafowl across its historical ranges over the past three decades in China during 2014-2017.Results： The Green Peafowl once habituated in 54 counties in China. Nearly 60% of the distribution counties were lost in the past three decades, with the left 22 counties distributed in central, southern and western Yunnan, SW China. Population decrease detected in all distribution areas except for Shuangbai and Xinping county where more than 60% of the total population is located. Only about 30% of the former bird population were recorded with the same interviewing method as 20 years ago.Three birds, 1 carcass, 6 calls and 12 footprints were detected along the 865 km line transects, indicating extremely low encounter rate of Green Peafowl in field. Sharp decreases in flock sizes were also detected, from 8-20 birds per flock in the 1990s to 3-5 birds at present. Poaching and habitat conversion are two widespread and long-lasting threats, while poison tion affect regional population＇s survival. Large flocks of 18 ng caused mortality in the past and hydropower construc -27 birds were discovered in the field, which increases our confidence of population recovery of this endangered pheasant in China.Conclusions： Only interviewed bird number and counts based on line transects were presented in this study, without further population estimation due to limitation of the data sets. Although the actual population of this cryptic bird must be underestimated, dramatic population declines and distribution concentrations of the endangered Green Peafowl occurred over the past 30 years in China undoubtedly.展开更多
Paracalanus parvus, Paracalanus crassirostris , and Acartia bifilosa are dominant and widely distributed in the Bohai Sea, and comprise an important part of zooplankton in terms of biomass as well as production rate. ...Paracalanus parvus, Paracalanus crassirostris , and Acartia bifilosa are dominant and widely distributed in the Bohai Sea, and comprise an important part of zooplankton in terms of biomass as well as production rate. In order to understand their seasonal distribution and population dynamics, their stage specific abundance in different months of the year were analyzed based on the never analyzed yet samples collected in 1959. The three species showed clear and remarkable seasonal variation in abundance, which maximized in spring and summer, when they formed high biomass patches or concentrations in the nearshore area. For Paracalanus parvus , two peaks were observed in the annual circle, one in June and the other in September. For Paracalanus crassirostris , one peak occurred in summer and a small one in December. The seasonal pattern of Acartia bifilosa was different in different regions. In Bohai Bay it had a two peak pattern, with the first large peak occurring in May and the second one in October. In Laizhou Bay, a winter peak in December and January could be observed besides the spring one. The number of generations during the reproductive season for the three species was estimated based on the annual cycle in abundance and ambient temperature.展开更多
Understanding how population sizes vary over time is a key aspect of ecological research. Unfortunately, our under- standing of population dynamics has historically been based on an assumption that individuals are ide...Understanding how population sizes vary over time is a key aspect of ecological research. Unfortunately, our under- standing of population dynamics has historically been based on an assumption that individuals are identical with homogenous life-history properties. This assumption is certainly false for most natural systems, raising the question of what role individual variation plays in the dynamics of populations. While there has been an increase of interest regarding the effects of within popula- tion variation on the dynamics of single populations, there has been little study of the effects of differences in within population variation on patterns observed across populations. We found that life-history differences （clutch size） among individuals ex- plained the majority of the variation observed in the degree to which population sizes of eastern fence lizards Sceloporus undula- tus fluctuated. This finding suggests that differences across populations cannot be understood without an examination of differences at the level of a system rather than at the level of the individual展开更多
In this work, we construct a stage-structured single population system with winter hiber- nation and impulsive effect in polluted environment. All solutions of the investigated system are proved to be uniformly ultima...In this work, we construct a stage-structured single population system with winter hiber- nation and impulsive effect in polluted environment. All solutions of the investigated system are proved to be uniformly ultimately bounded. The conditions of the population- extinction solution of the investigated system are obtained. The permanent condition of the investigated system is also obtained. Finally, numerical analysis is inserted to illustrate the results. Our results indicate that the environmental pollution will reduce biological diversity of the natural world. Our results also provide reliable tactic basis for the practical biological resource management.展开更多
基金the financial supports from the Biodiversity Conservation Fund from Yunnan Environmental Protection DepartmentSpecial Funds for Green Peafowl Investigation from State Forestry Administration of the People’s Republic of Chinasupported by the Key Laboratory of Special Biological Resource Development and Utilization of Universities in Yunnan Province
文摘Background： Understanding the changes in population dynamics, including demographics, distribution and threats is essential for species status assessing.The endangered Green Peafowl （Povo muticus） has experienced sharp population declines and d stribution range diminishing both in China and Southeast Asia. Field population surveys have not been conducted in China since the 1990s, which hindered conservation planning and decision-making.Methods： With interview and line transects methods, we figured out the population and distribution changes of Green Peafowl across its historical ranges over the past three decades in China during 2014-2017.Results： The Green Peafowl once habituated in 54 counties in China. Nearly 60% of the distribution counties were lost in the past three decades, with the left 22 counties distributed in central, southern and western Yunnan, SW China. Population decrease detected in all distribution areas except for Shuangbai and Xinping county where more than 60% of the total population is located. Only about 30% of the former bird population were recorded with the same interviewing method as 20 years ago.Three birds, 1 carcass, 6 calls and 12 footprints were detected along the 865 km line transects, indicating extremely low encounter rate of Green Peafowl in field. Sharp decreases in flock sizes were also detected, from 8-20 birds per flock in the 1990s to 3-5 birds at present. Poaching and habitat conversion are two widespread and long-lasting threats, while poison tion affect regional population＇s survival. Large flocks of 18 ng caused mortality in the past and hydropower construc -27 birds were discovered in the field, which increases our confidence of population recovery of this endangered pheasant in China.Conclusions： Only interviewed bird number and counts based on line transects were presented in this study, without further population estimation due to limitation of the data sets. Although the actual population of this cryptic bird must be underestimated, dramatic population declines and distribution concentrations of the endangered Green Peafowl occurred over the past 30 years in China undoubtedly.
文摘Paracalanus parvus, Paracalanus crassirostris , and Acartia bifilosa are dominant and widely distributed in the Bohai Sea, and comprise an important part of zooplankton in terms of biomass as well as production rate. In order to understand their seasonal distribution and population dynamics, their stage specific abundance in different months of the year were analyzed based on the never analyzed yet samples collected in 1959. The three species showed clear and remarkable seasonal variation in abundance, which maximized in spring and summer, when they formed high biomass patches or concentrations in the nearshore area. For Paracalanus parvus , two peaks were observed in the annual circle, one in June and the other in September. For Paracalanus crassirostris , one peak occurred in summer and a small one in December. The seasonal pattern of Acartia bifilosa was different in different regions. In Bohai Bay it had a two peak pattern, with the first large peak occurring in May and the second one in October. In Laizhou Bay, a winter peak in December and January could be observed besides the spring one. The number of generations during the reproductive season for the three species was estimated based on the annual cycle in abundance and ambient temperature.
文摘Understanding how population sizes vary over time is a key aspect of ecological research. Unfortunately, our under- standing of population dynamics has historically been based on an assumption that individuals are identical with homogenous life-history properties. This assumption is certainly false for most natural systems, raising the question of what role individual variation plays in the dynamics of populations. While there has been an increase of interest regarding the effects of within popula- tion variation on the dynamics of single populations, there has been little study of the effects of differences in within population variation on patterns observed across populations. We found that life-history differences （clutch size） among individuals ex- plained the majority of the variation observed in the degree to which population sizes of eastern fence lizards Sceloporus undula- tus fluctuated. This finding suggests that differences across populations cannot be understood without an examination of differences at the level of a system rather than at the level of the individual
基金Acknowledgments The work of the first author was supported by National Natural Science Foundation of China （No. 11361014） and the project of high level creative talents in Guizhou Province （No. 20164035）. This research was supported by National Natural Science Foundation of China （Nos. 11361014, 10961008）, the Science Technology Foundation of Guizhou Education Department （No. 2008038）, and the Science Technology Foundation of Guizhou （No. 2010J2130）.
文摘In this work, we construct a stage-structured single population system with winter hiber- nation and impulsive effect in polluted environment. All solutions of the investigated system are proved to be uniformly ultimately bounded. The conditions of the population- extinction solution of the investigated system are obtained. The permanent condition of the investigated system is also obtained. Finally, numerical analysis is inserted to illustrate the results. Our results indicate that the environmental pollution will reduce biological diversity of the natural world. Our results also provide reliable tactic basis for the practical biological resource management.
