Longitudinal Gradient Patterns Of Taxonomic,Functional And Phylogenetic Diversity Of Fish Communities In The Qiupu River

Biodiversity includes many aspects,among which the most commonly considered is the biological taxonomic,functional and phylogenetic aspects.In the context of the current biodiversity crisis,understanding how these aspects are distributed and what are the determinants have become the focus of attention.Determing the spatial and temporal distribution pattern of fish diversity is the scientific basis for the protection and management of fish resources.The spatial distribution of fish diversity along the longtitudinal gradient of river has been widely reported,but most of the exsting studies focus on the taxonomic ? diversity based on species composition,while the ? diversity and functional diversity,phylogenetic diversity of fish and their responses to environmental changes are not very clear.Therefore,in this paper,the Qiupu River in the mountainous area of Southern Anhui Province is taken as the research area,and the investigation samples are set continuously from the source to the estuary along the longtitudinal gradient of the river.Based on the species composition,functional traits and phylogenetic distance of fish,? and ? diversity of the taxonomic,functional and phylogenetic diversity were studied: 1)The species composition of fish community and its longtitudinal gradient pattern were analyzed by the differences of local habitat conditions,terrestrial landscape characteristics and spatial location of tributaries along the upstream and downstream of the river;2)The taxonomic,functional and phylogenetic diversity of fish and the relationship between ? and ? diversity along longtitudinal gradient;3)Whether there is spatial consistency among the taxonomic,functional and phylogenetic diversity of fish communities along the longtitudinal gradient of the river.The main results of this study are as follows:(1)Along the longtitudinal gradient of the river,the velocity,C-link,boulders and forestland area are negatively correlated with the distance to the source of the river.The water temperature,electrical conductivity,water width,water depth,link,D-link,stream order,broken sand,cultivated land area and beach area increased significantly with the increase of the distance form headwater.There were significant differences in fish communities between river reaches and seasons.The fish in the upper and middle reaches overlapped but were separable,and they were obviously separate from those in the lower reaches.For the fish community structure in Qiupu River during the wet reason,it was significantly affected by the local habitat variables of water depth and flow velocity.In addition to the two factors,the fish community in Qiupu River was also significantly affected by p H during the dry season.(2)? diversity was calculated based on species composition,functional traits and phylogenetic distance of fish community,the results showed that: 1)The taxonomic ? diversity indices were affected by river reach and season independently,and Pielou index was affected by the interaction of the two;FEve was only affected by the interaction between season and reach,FDiv was affected by the two separately,and FRic was only affected by the reach;2)Taxonomic ? diversity indices showed a linear relationship with the distance from headwater expect for Pielou index;FDiv,FRic,PSR and PSV showed a linear relationship with the distance from headwater.(3)Based on the distribution pattern of taxonomic,functional and phylogenetic ? diversity along the alongtitudinal gradient,the results showed that: 1)turnover component was in both taxonomic and functional ? diversity in wet season,but nestedness component was dominant in functional ? diversity in dry season.2)The taxonomic ? diversity index was affected by reach and season alone,and the Taxsim and Taxnes indexes were both affected by their interaction;Funs(?)r and Funsim were only affected by season,while Funnes was only affected by reach;3)Except for the Taxnes index in the wet season,there was a linear relationship between the taxonomic ? diversity index and the distance from headwater;Only the Funnes index showed a significant linear relationship with the distance from headwater during the dry season.There was a significant linear relationship between phylogenetic ? diversity and the distance from headwater.In the upper reaches of Qiupu River,SES.MFD and SES.MPD were less than 0,related to the fish community was composed of closely related species with similar functions,while the SES.MFD was more than 0 but the SES.MPD was less than 0.That is to say,the fish community in the downstream is composed of closely related species with different functions.(4)Taxonomic,functional,phylogenetic ? diversity were significantly correlated with species richness.The correlation between phylogenetic diversity and species richness was higher than that between taxonomic and functional diversity.There was a significant correlation between MFD and MPD.However,Funs(?)r has no significant correlation with Taxs(?)r.The research results showed that along the the longitudinal gradient,there is a high degree of correlation between different biological ? diversity,including the spatial pattern of high similarity.But spatial and temporal pattern of ? diversity were different.Taxonomic ? diversity dominated by species turnover,but the contribution rate of function turnover decreased greatly for the functional ? diversity.This study found weak correlations between indices of ? diversity,and we speculated that using a set of comprehensive data involving multiple dimensions to calculate functional diversity may not be enough to capture the intrinsic dimensions and fully describe the functional variation of species included in our study.