Dispersal Pattern,gut Microbiota And Parasite Responses Of The Moose Population In Northeastern China To Climate Warming

As a representative species of global cold adaptation,moose(Alces alces)has a low tolerance to high temperatures.As climate warming forced the moose in northeastern China to retreat to high latitudes and high altitudes,the species lost nearly half of its historical distribution in the past 40 years.Therefore,moose is an ideal species to study the effects of climate warming on large mammals.In this study,population genetic analysis,fecal microscopic analysis,nutrient content determination,and microbiome sequencing were used to elucidate the regulatory mechanisms of moose populations under the background of climate warming.We evaluated the dispersal behavior-driven effects of climate warming on moose populations and revealed the adaptive mechanisms and regulatory processes of moose genetics,nutrition,and gut microbes to spatially heterogeneous warming.Meanwhile,fecal genetic samples from different moose populations were analyzed to quantify the dispersal patterns from a genetic perspective.To compare the differences in the composition and functional structure of the moose gut microbial community between different dispersal patterns and clarify the influencing factors of the gut microbial characteristics.Finally,the infection rate and infection intensity of parasites in different moose populations were compared and the influencing factors of parasite infection were analyzed to reveal the ecological driving mechanism of parasite-host antagonism.The main findings are as follows:1 Effect of climate warming on gut microbiota,nutrition,and gene flow in moose populationsBAYESASS methods were applied to assess the recent dispersal intensity and direction of moose populations,and network analysis was used to explore the cascading effects of environmental conditions on gene flow,nutritional strategies,and gut microbiota adaptation during moose population retreat.The results showed that the direction and intensity of gene flow were consistent with global warming driving retreats of moose populations.We interpret this as evidence for the northward movement of moose populations,with cooler northern populations receiving more immigrants and warmer southern populations supplying emigrants.In addition,the warmer late spring temperatures were associated with plant community composition and facilitated related changes in moose protein and carbohydrate intake through altering forage availability,forage quality,and diet composition.The key macronutrients of moose were significantly related to the presence of Anaerotruncus(protein: r =-0.364,p =0.031),Roseburia(protein: r = 0.395,p = 0.019;carbohydrates: r =-0.449,p = 0.007),Ruminococcus(carbohydrates: r = 0.408,p = 0.015),Enterococcus(carbohydrates: r =-0.355,p = 0.037),glycolysis II(from fructose 6-phosphate)(carbohydrates: r = 0.345,p = 0.042),Lhistidine degradation I(carbohydrates: r = 0.479,p = 0.004)and isoprene biosynthesis I(carbohydrates: r = 0.346,p = 0.042).These nutrient shifts were accompanied by changes in gut microbial composition and functional pathways related to nutrient metabolism.2.The impact of climate warming on the moose gut microbiota under different dispersal patternsThis study quantified the moose dispersal patterns and combined 16 s r RNA and metagenomic sequencing technologies to explore the ecological driving mechanisms of host and gut microbial composition and functional structure between different dispersal patterns.The results showed that the moose populations in northeastern China were experiencing two dispersal patterns during the northward retreat,namely: dispersing population and isolated population.Dispersing populations spread from southeast to northwest,while isolated populations were in relatively stable population dynamics.There were also significant differences in gut microbial composition and the abundance of functional pathways related to digestion and dietary composition between dispersing and isolated moose populations.There were significant differences between the different dispersal patterns in the abundances of Roseburia(p = 0.039),Faecalibacterium(p = 0.039),rc4-4(p = 0.011),Bulleidia(p = 0.030)and Escherichia(p = 0.035).The HUMAn N2 results also suggested differentially functional structures between the dispersing and isolated moose populations.Notably,UDP-Nacetylmuramoyl-pentapeptide biosynthesis(I,p = 0.013;II,p = 0.025)and Peptidoglycan biosynthesis I(p = 0.016)pathways were strikingly enriched in the dispersing populations compared with isolated populations.In addition,the functional pathways of L-histidine degradation I(p = 0.032)and pp Gpp biosynthesis(p = 0.035)were more abundant in isolated populations compared with the dispersing populations.Meanwhile,among the gut bacteria of the dispersing populations,Firmicutes,Bacteroidetes and Firmicutes/Bacteroidetes ratios showed an obvious and continuous trend of abundance changes among Zhanhe-Nanwenghe-Mohe populations.However,no similar regularity was found in isolated populations.Finally,key environmental variables affecting the gut microbial communities also changed between the different moose dispersal patterns.The gut microbiota of isolated populations was only related to ambient temperature,while the dispersing populations were related to longitude and protein intake.3.Effects of climate warming on parasitic infection of moose populations under different dispersal patternsThe types and infection intensity of parasites between different moose populations’ dispersal patterns were compared and analyzed by the saturated sugar-salt water flotation method and Mc Master counting method to reveal the ecological driving mechanism of moose dispersal behavior and parasite antagonism.The results showed that parasite infection was common among moose populations in northeastern China,with an individual infection rate of72.06%.198 feces from 68 individuals were detected by parasite eggs and found that moose were co-infected with 4 classes and 8 types of parasites.Including Nematoda: nemafodirus,roundworms,whipworms,strongyloides,and unknown nematodes;Cestoda: tapeworms;Sporozoa: coccidia;Trematoda: trematodes.Among them,the highest individual infection rate was nemafodirus(35.29%),followed by coccidia(33.82%).From the average infection intensity of parasites,coccidia(24.38 n/g)and tapeworms(23.96 n/g)have higher average infection intensity.In addition,there was a certain ecological response between the infection of gastrointestinal parasites and the gene exchange intensity of the host.There was a significant positive correlation between warming and the intensity of parasite infection.We found that climate warming makes the risk of parasite transmission more pronounced in isolated populations(Pearson’s,dispersing: r = 0.541,p = 0.025;isolated: r = 0.942,p < 0.0001).Meanwhile,the influencing factors of parasitic infection in moose populations with different dispersal patterns were not consistent.The specificity of parasitic infection between populations caused by dispersal may be related to the physiological adaptation of the host caused by changes in environmental stress hormones.