Effects Of Foraging Site Distances On The Intestinal Bacterial Community Compositions Of The Sympatric Wintering Hooded Crane (Grus Monacha) And Domestic Duck (Anas Platyrhynchos Domesticus)

The stable animal intestinal microflora plays a crucial role in growth,development of the host and immune homeostasis.The structure of intestinal microflora is affected by cross-species transmission.In the nature reserve,the foraging habitat of migratory birds is relatively fixed and domestic poultry is also present in the surrounding areas.Therefore,it is of practical and theoretical value to study the mutual influence of gut bacteria(including potential pathogenic bacteria)of migratory birds and domestic poultry for strengthening wildlife management.This study was conducted during over wintering period and fecal samples were collected from hooded cranes(Grus monacha)and two groups of domestic ducks(Anas platyrhynchos domesticus)present within 1 km(D-N)and 4 km away(D-F)in the Shengjin Lake area.By using high-throughput sequencing(llumina Hi Seq)technology and bioinformatics analysis software the temporal and spatial characteristics of intestinal bacteria and potential pathogens of hooded crane and domestic ducks were analyzed.The results of this study are as follows:1.An obvious cross-species transmission of intestinal microbes was observed between hooded cranes and domestic ducks throughout the wintering period.The hooded crane and domestic ducks present at distance of 1 km have more shared bacterial OTU(Operational Taxonomic Unit),dominant bacteria phyla,and core bacteria.A total of 7944 bacterial OTUs were present in the intestines of hooded cranes and domestic ducks,and the shared bacterial OTU accounts for 25.7%.The shared bacterial OTU between hooded crane and domestic ducks present at 4 km distance accounted for 20.2%.Four phyla were dominant across all samples i.e.Firmicute,Bacteroidetes,Proteobacteria and Cyanobacteria.The different intestinal bacterial groups were screened from phylum to specie level in this study.There were significant differences present among two core phyla cyanobacteria and Actinobacteria(P<0.05)in hooded cranes and domestic ducks.Thirty four bacterial groups were found in the intestines of domestic ducks present at near distance and two different bacterial groups were present in the intestines of domestic duck present at long distance.The two bacterial species,Bacillus aceticus and Lactobacillus acidipiscis with highest relative abundance were found in hooded cranes and domestic ducks present within close range.The intestinal bacterial community composition of hooded cranes and domestic ducks exhibited significant differences and have a more significant aggregation trend(R=0.815,P=0.001).2.During the changing winter period,the cross-transmission of intestinal bacteria between hooded cranes and domestic ducks become prominent.The smaller difference and significant overlap were observed in intestinal bacterial communities between species present at close distance.We identified a total of 24 bacterial phyla during three winter periods(early,middle and late)and 18 phyla overlapped in each period of winter.In domestic ducks a total of 29 bacterial phyla were found and among them 20 phyla were shared during three periods of winter.The domestic ducks present at a long distance(D-F)have a total of 27 bacterial phyla throughout winter period and there were 21 bacterial phyla in each wintering period.With the change of overwintering period,the alpha diversity of hooded cranes changed from extremely significant(P<0.01)to insignificant(P>0.05),and the intestinal bacterial OTU enrichment was gradually higher in domestic ducks at close distances than domestic ducks at long distances.In general,the differential flora of the intestines of hooded cranes and domestic ducks was constantly changing,reaching up to 45 differential flora categories in the middle period.The number of core bacteria in the intestinal tract of hooded cranes and domestic ducks showed a constant change,with increase in the contribution rate.The most significant changes are Paenisporsarcina,Nostocoid,and Clostrium.3.The cross transmission of intestinal bacterial pathogens of hooded cranes and domestic ducks is related to distance between the two species.The degree of cross-infection gradually increases with the changing winter period.The potential pathogenic sequences in the intestine of hooded cranes and domestic ducks accounted for 3.69% of the total number of bacteria,and the number of pathogenic sequences in domestic duck populations was higher than hooded cranes.The OTU richness of pathogenic bacteria was higher in domestic ducks than hooded cranes and the alpha diversity of potential pathogenic bacteria of hooded cranes showed significant difference than domestic ducks(P<0.05).Enterococcus cecorum and Clostridium botulinum were the most important species found in the intestine of hooded cranes and domestic ducks.The overlap of potential pathogenic bacteria sequences between hooded cranes and domestic ducks increased from 0.22% in the early overwintering period to0.33% in the late overwintering period.It is the first time to compare and analyze the composition,commonality and difference of the intestinal flora of hooded cranes and domestic ducks at different distances under temporal and spatial changes,as well as the formation mechanism of the diversity of potential pathogens in the study.This is the definition of wild birds and free-range poultry in nature reserves.The safe distance between the two species has provided a basis for exploring the transmission mechanism of rare bird infectious diseases.