Species richness in any area results from the interplay of the processes of speciation,extinction,and dispersal.The relationships between species richness and climate should be considered as an outcome of the effects ...Species richness in any area results from the interplay of the processes of speciation,extinction,and dispersal.The relationships between species richness and climate should be considered as an outcome of the effects of climate on speciation,extinction,and dispersal.Diversificationrate represents the balance of speciation and extinction rates over time.Here,I explore diversificationrates in mosses across geographic and climatic gradients worldwide.Specifically,I investigate latitudinal patterns and climatic associations of the mean diversificationrate of mosses at global,hemispheric,and smaller scales.I findthat the mean diversificationrate of mosses is positively correlated with species richness of mosses,increases with decreasing latitude and increasing mean annual temperature and annual precipitation,and is more strongly associated with mean annual temperature than with annual precipitation.These findingsshed light on variation of species richness in mosses across the world.The negative relationship between species richness and latitude and the positive relationship between species richness and mean diversificationrate in mosses suggest that higher moss species richness at lower latitudes might have resulted,at least to some degree,from higher moss diversificationrates at lower latitudes.展开更多
This study examines the return connectedness between decentralized finance(DeFi)’s and the Association of Southeast Asian Nations(ASEAN)stock markets using the quantile vector autoregressive framework,which allows us...This study examines the return connectedness between decentralized finance(DeFi)’s and the Association of Southeast Asian Nations(ASEAN)stock markets using the quantile vector autoregressive framework,which allows us to investigate the connectedness at conditional quantiles.Our sample includes four major DeFi’s and six ASEAN stock markets,spanning from March 2018 to December 2022.The static results indicate a moderate level of return transmission between the system at mean and median quantile.This propagation increases substantially under extreme market conditions,establishing an asymmetric transmission across quantiles.Despite being a relatively new asset class,DeFi dominates the equity market and acts as the primary shock transmitter to the system in most instances.The dynamic analysis reveals that total system connectedness fluctuates over time and quantiles.The total system connectedness peaked during the COVID-19 and the Russia–Ukraine conflict period,indicating the impact of global events on system transmission.The optimal weight and hedge ratio estimated using the DCC-GARCH model indicate that DeFi is beneficial for portfolio construction and risk management.The rising trend in dynamic optimal weight and hedge ratio during the COVID-19 pandemic demonstrates that investors should decrease their investments in DeFi and increase hedging costs.Therefore,portfolio managers and investors should readjust their portfolio allocation in a timely manner according to different market states to build additional effective hedging and diversification strategies to avoid large losses and to reduce portfolio risk exposure.展开更多
文摘Species richness in any area results from the interplay of the processes of speciation,extinction,and dispersal.The relationships between species richness and climate should be considered as an outcome of the effects of climate on speciation,extinction,and dispersal.Diversificationrate represents the balance of speciation and extinction rates over time.Here,I explore diversificationrates in mosses across geographic and climatic gradients worldwide.Specifically,I investigate latitudinal patterns and climatic associations of the mean diversificationrate of mosses at global,hemispheric,and smaller scales.I findthat the mean diversificationrate of mosses is positively correlated with species richness of mosses,increases with decreasing latitude and increasing mean annual temperature and annual precipitation,and is more strongly associated with mean annual temperature than with annual precipitation.These findingsshed light on variation of species richness in mosses across the world.The negative relationship between species richness and latitude and the positive relationship between species richness and mean diversificationrate in mosses suggest that higher moss species richness at lower latitudes might have resulted,at least to some degree,from higher moss diversificationrates at lower latitudes.
文摘This study examines the return connectedness between decentralized finance(DeFi)’s and the Association of Southeast Asian Nations(ASEAN)stock markets using the quantile vector autoregressive framework,which allows us to investigate the connectedness at conditional quantiles.Our sample includes four major DeFi’s and six ASEAN stock markets,spanning from March 2018 to December 2022.The static results indicate a moderate level of return transmission between the system at mean and median quantile.This propagation increases substantially under extreme market conditions,establishing an asymmetric transmission across quantiles.Despite being a relatively new asset class,DeFi dominates the equity market and acts as the primary shock transmitter to the system in most instances.The dynamic analysis reveals that total system connectedness fluctuates over time and quantiles.The total system connectedness peaked during the COVID-19 and the Russia–Ukraine conflict period,indicating the impact of global events on system transmission.The optimal weight and hedge ratio estimated using the DCC-GARCH model indicate that DeFi is beneficial for portfolio construction and risk management.The rising trend in dynamic optimal weight and hedge ratio during the COVID-19 pandemic demonstrates that investors should decrease their investments in DeFi and increase hedging costs.Therefore,portfolio managers and investors should readjust their portfolio allocation in a timely manner according to different market states to build additional effective hedging and diversification strategies to avoid large losses and to reduce portfolio risk exposure.
