Background:In China since the first human infection of avian influenza A(H7N9)virus was identified in 2013,it has caused serious public health concerns due to its wide spread and high mortality rate.Evidence shows tha...Background:In China since the first human infection of avian influenza A(H7N9)virus was identified in 2013,it has caused serious public health concerns due to its wide spread and high mortality rate.Evidence shows that bird migration plays an essential role in global spread of avian influenza viruses.Accordingly,in this paper,we aim to identify key bird species and geographical hotspots that are relevant to the transmission of avian influenza A(H7N9)virus in China.Methods:We first conducted phylogenetic analysis on 626 viral sequences of avian influenza A(H7N9)virus isolated in chicken,which were collected from the Global Initiative on Sharing All Influenza Data(GISAID),to reveal geographical spread and molecular evolution of the virus in China.Then,we adopted the cross correlation function(CCF)to explore the relationship between the identified influenza A(H7N9)cases and the spatiotemporal distribution of migratory birds.Here,the spatiotemporal distribution of bird species was generated based on bird observation data collected from China Bird Reports,which consists of 157272 observation records about 1145 bird species.Finally,we employed a kernel density estimator to identify geographical hotspots of bird habitat/stopover that are relevant to the influenza A(H7N9)infections.Results:Phylogenetic analysis reveals the evolutionary and geographical patterns of influenza A(H7N9)infections,where cases in the same or nearby municipality/provinces are clustered together with small evolutionary differences.Moreover,three epidemic waves in chicken along the East Asian-Australasian flyway in China are distinguished from the phylogenetic tree.The CCF analysis identifies possible migratory bird species that are relevant to the influenza A(H7N9)infections in Shanghai,Jiangsu,Zhejiang,Fujian,Jiangxi,and Guangdong in China,where the six municipality/provinces account for 91.2%of the total number of isolated H7N9 cases in chicken in GISAID.Based on the spatial distribution of identified bird species,geographical hotspots are furt展开更多
Summary Darwin proposed that pollen size should be positively correlated with stigma depth rather than style length among species given that pollen tubes first enter the stigma autotrophically, then grow through the s...Summary Darwin proposed that pollen size should be positively correlated with stigma depth rather than style length among species given that pollen tubes first enter the stigma autotrophically, then grow through the style heterotrophically. However, studies often show a posi-tive relationship between pollen size and style length. Five floral traits were observed to be correlated among 42 bumblebee-pollinated Pedicularis species （Orobancha- ceae） in which stigmas are distinct from styles. The phylogenetic independent contrast analysis revealed that pollen grain volume was more strongly correlated with stigma depth than with style length, consistent with Darwin＇s functional hypothesis between pollen size and stigma depth.展开更多
基金This work was supported by the Hong Kong Research Grants Council(RGC/HKBU12202415)the National Natural Science Foundation of China(Grant Nos.81402760,81573261)+2 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161563)Computational work was partially supported by Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(Grant No.U1501501)The funders had no role in study design,data collection and analysis,decision to publish,or preparation of the manuscript。
文摘Background:In China since the first human infection of avian influenza A(H7N9)virus was identified in 2013,it has caused serious public health concerns due to its wide spread and high mortality rate.Evidence shows that bird migration plays an essential role in global spread of avian influenza viruses.Accordingly,in this paper,we aim to identify key bird species and geographical hotspots that are relevant to the transmission of avian influenza A(H7N9)virus in China.Methods:We first conducted phylogenetic analysis on 626 viral sequences of avian influenza A(H7N9)virus isolated in chicken,which were collected from the Global Initiative on Sharing All Influenza Data(GISAID),to reveal geographical spread and molecular evolution of the virus in China.Then,we adopted the cross correlation function(CCF)to explore the relationship between the identified influenza A(H7N9)cases and the spatiotemporal distribution of migratory birds.Here,the spatiotemporal distribution of bird species was generated based on bird observation data collected from China Bird Reports,which consists of 157272 observation records about 1145 bird species.Finally,we employed a kernel density estimator to identify geographical hotspots of bird habitat/stopover that are relevant to the influenza A(H7N9)infections.Results:Phylogenetic analysis reveals the evolutionary and geographical patterns of influenza A(H7N9)infections,where cases in the same or nearby municipality/provinces are clustered together with small evolutionary differences.Moreover,three epidemic waves in chicken along the East Asian-Australasian flyway in China are distinguished from the phylogenetic tree.The CCF analysis identifies possible migratory bird species that are relevant to the influenza A(H7N9)infections in Shanghai,Jiangsu,Zhejiang,Fujian,Jiangxi,and Guangdong in China,where the six municipality/provinces account for 91.2%of the total number of isolated H7N9 cases in chicken in GISAID.Based on the spatial distribution of identified bird species,geographical hotspots are furt
基金supported by the National Science Foundation of China (Grants no.31270281, U1402267) to SQH
文摘Summary Darwin proposed that pollen size should be positively correlated with stigma depth rather than style length among species given that pollen tubes first enter the stigma autotrophically, then grow through the style heterotrophically. However, studies often show a posi-tive relationship between pollen size and style length. Five floral traits were observed to be correlated among 42 bumblebee-pollinated Pedicularis species （Orobancha- ceae） in which stigmas are distinct from styles. The phylogenetic independent contrast analysis revealed that pollen grain volume was more strongly correlated with stigma depth than with style length, consistent with Darwin＇s functional hypothesis between pollen size and stigma depth.
