| Nanhui Dongtan Wetland is an important node on the East Asia-Australasia waterfowl migration route,and an important stopover and wintering place for waterbirds.Beaches,Dishui Lake,Chifeng Harbor,basic farmland,Dongyin River and reed land are the main areas where waterfowl inhabit and forage in Nanhui Dongtan Wetland.Nanhui Dongtan is rich in bird resources,and a variety of nationally protected animals often live here.In order to explore the preference of waterfowl to the wetlands of Nanhui Dongtan,we selected Dishui Lake,Chifeng Harbor,Basic Farmland,and Dongyin River,which are accessible to investigators,as the research area.In November and December 2020,January,February,November and December in 2021,and January and February in 2022,we will conduct a 2-year waterbird diversity survey once a month for a total of 8 times.We recruited bird-watching volunteers and divided them into groups to investigate the species and numbers of waterbirds in each area using the regional direct number method,so as to analyze the bird diversity of the four wetlands and the changes of wintering waterfowl in the four wetlands during 2a.A total of 34,792 waterbirds of 60 species were recorded in this survey,belonging to 9 orders and 13 families.Anseriformes,Ploveriformes and Pliformes have the largest number of water birds.There are 3 species of national first-class protected animals and6 species of national second-class protected animals.There are 1 critically endangered species,1 vulnerable species and 6 near-threatened species recorded in the IUCN World Conservation Union Red List.Recorded 3 species listed in Appendix II of CITES Convention on International Trade in Endangered Wild Fauna and Flora.From the type of residence,winter migratory birds occupy an absolute advantage(35 species,31970times).This survey recorded counts of ribbed ducks reaching the threshold of 1% of the species’ global population.Analysis of waterfowl density among the four wetlands shows that the highest density of waterbirds in Chifenggang is 185 per hectare.The overall trend is Chifenggang > Dongyinhe Wetland > Dishui Lake > basic farmland.The density of waterbirds in Chifenggang is significantly higher than that of Basic farmland.It shows that Chifeng Harbor is highly attractive to waterfowl among the wetlands in the embankment of Nanhui Dongtan,and it is an indispensable wetland in Nanhui Dongtan.Classify waterfowl as swimming birds and wading birds,and study the interannual changes of swimming birds and wading birds in the four wetlands.The results showed that the swimming birds were mainly distributed in Dishui Lake and Chifeng Harbor.From year to year,the number of swimming birds in Dishui Lake increased,while that in Chifeng Harbor decreased.The wading birds are mainly distributed in the basic farmland and the Dongyin River wetland.Between years,the basic farmland wading birds increase,and the Dongyin River wetland wading birds decrease.However,there was no significant difference between years for both swimming birds and wading birds.In addition,the habitats of four wetlands also changed during the period of 2 years,and the open water area of Chifenggang Lake decreased by about 18.541 hectares.The exposed river beach may have attracted some swimming birds.In conclusion,the results of this study show that Chifeng Harbor is an irreplaceable wetland area in the Nanhui Dongtan area.During the period of 2 years,the bird species distribution and community composition in the four wetlands changed,among which the changes in Chifenggang and Dongyinhe were the largest,which may be related to the large reduction of the open water area of the wetlands.Previous studies have shown that animal feeding habits are closely related to energy metabolism and survival adaptation.Energy metabolism mainly occurs in mitochondria,which encode 13 protein subunits that are an important part of the oxidative phosphorylation complex.The diet and nutrient intake of organisms have a profound impact on their morphology and structure.The diet type of birds is also closely related to their morphology,behavior,ecological niche and survival strategy,and is one of the important factors that cannot be ignored in the evolution of birds.one.In order to study the adaptive evolution relationship between bird feeding habits and mitochondrial genomes,we selected 20 species of Anseriformes and divided them into three groups according to their feeding habits: carnivorous group,herbivorous group,and omnivorous group,and downloaded their mitochondria through NCBI Genome,conduct adaptive evolution analysis,relaxation selection analysis,polymorphic amino acid site detection and 3D structure prediction analysis on the mitochondrial genome and 13 protein genes to study the evolutionary performance of the mitochondrial protein-coding genes of these three groups of birds.The results showed that the evolution rate of the mitochondrial genome of carnivorous birds was higher than that of herbivorous and omnivorous birds,and only the mitochondrial protein-coding genes of carnivorous birds were subject to relaxed selection pressure.In addition,the detection of polymorphic amino acid sites showed that the number of polymorphic sites and harmful sites in the proteins encoded by the mitochondrial genome of the carnivorous group was much higher than that of the herbivorous and omnivorous groups.In the omnivorous group,the evolution rate of the mitochondrial protein-coding genes was lower,most of the genes were subjected to enhanced selection,and there were fewer polymorphic sites in the protein sequences.This study provides a theoretical basis for the impact of dietary differences on the adaptive evolution of bird mitochondrial genomes. |
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