| Skin microbiota plays an important role in helping the host adapt to different environments and maintain host health.During the development of amphibians,the habitat environment changes from aquatic to amphibious,and the skin structure changes with individual development.These changes will affect the nutritional source and living space of skin microbiota,and then lead to changes in the composition and diversity of skin microbiota.Studying the characteristics of amphibian skin microbiota combined with individual development characteristics is helpful to understand the adaptation mechanism of amphibian skin microbiota to environmental changes during development.In this study,Hynobius maoershanensis was studied in Zhuangyuan Bridge,Bajiaotian and Shanding Lake of Maoershan National Nature Reserve,and the skin samples of its three developmental stages(forelimb bud stage,hindlimb bud stage and adult)were collected.The skin microbiota was sequenced by 16 S r RNA high-throughput sequencing technology.Alpha diversity,Beta diversity and species composition analyses were used to analyze the diversity of the skin microbiota of H.maoershanensis at different developmental stages.This study intends to answer the following questions:(1)What are the characteristics of skin microbiota in different developmental stages of H.maoershanensis?(2)How does the skin microbiota of H.maoershanensis adapt to environmental changes during its development?(3)Does habitat disturbance affect skin microbiota of H.maoershanensis?Alpha diversity analysis showed that:(1)The diversity of adult skin microbiota was significantly higher than that in forelimb bud stage,in which the Shannon index of adult was significantly higher than that in forelimb bud stage(q < 0.05),and the Simpson index was significantly lower than that in forelimb bud stage(q < 0.05).(2)The diversity of adult skin microbiota was significantly higher than that in hindlimb bud stage,in which the Shannon index of adult was significantly higher than that in hindlimb bud stage(q < 0.05),and the Simpson index was significantly lower than that in hindlimb bud stage(q < 0.05).(3)There was no significant difference in the diversity of skin microbiota between forelimb bud stage and hindlimb bud stage(q > 0.05).Habitat had different effects on the Alpha diversity of skin microbiota at different development stages,which were as follows:(1)There was no difference in the diversity of forelimb bud stage and adult skin microbiota between different habitats,and there was no significant difference in Shannon index and Simpson index(q > 0.05).(2)The diversity of skin microbiota in the hindlimb bud stage varied among different habitats.The Shannon index of skin microbiota in the hindlimb bud stage of Zhuangyuan Bridge was significantly higher than that in the Shanding Lake(q < 0.05),and the Simpson index was significantly lower than that in the Shanding Lake(q < 0.05),which showed that the Alpha diversity of hindlimb bud stage skin microbiota in the habitat with high disturbance degree was significantly higher than that in the habitat with low disturbance degree.Beta diversity analysis showed that there were significant differences in the composition of skin microbiota among forelimb bud stage,hindlimb bud stage and adult.There were differences between habitats in the composition of skin microbiota in the forelimb bud stage and adult,and there was no difference between habitats in the composition of skin microbiota in the hindlimb bud stage.The results of community composition analysis showed that,at the phylum level,the skin microbiota of forelimb bud stage mainly included Proteobacteria,Firmicutes and Fusobacteria.The skin microbiota in the hindlimb bud stage mainly included Proteobacteria,Firmicutes and Bacteroidetes.The adult skin microbiota mainly included Proteobacteria,Bacteroides,Actinobacteria,Acidobacteria,Firmicutes and Chloroflexi.The main phylum shared by the skin microbiota at different developmental stages was Proteobacteria and Firmicutes,and the dominant phylum was Proteobacteria.At the genus level,Limnohabitans was the dominant genus in the forelimb bud stage,and Polynucleobacter was the dominant genus in the hindlimb bud stage,and Pseudomonas was the dominant genus in the adult.The composition of skin microbiota of H.maoershanensis had difference at developmental stages.The results were as follows:(1)In the comparison of skin microbiota between the forelimb bud stage and the hindlimb bud stage,the proportion of Fusobacteriota,Chlamydiae,Limnohabitans and Pseudomonas in the forelimb bud stage was significantly higher than that in the hindlimb bud stage,and the proportion of Bacteroidota,Spirochaetes,Verrucomicrobia and Polynucleobacter in the hindlimb bud stage was significantly higher than that of forelimb bud stage.(2)In the comparison of skin microbiota between forelimb bud stage and adult,the proportion of Fusobacteriota,Limnohabitans and Polynucleobacter in the forelimb bud stage was significantly higher than that in the adult,and the proportion of Bacteroidota,Acidobacteria,Actinobacteria,Chloroflexi,Verrucomicrobia,Flavobacterium,Janthinobacterium and Acinetobacter in the adult was significantly higher than that in the forelimb bud stage.(3)In the comparison of skin microbiota between hindlimb bud stage and adult,the proportion of Proteobacteria,Polynucleobacter and Limnohabitans in the hindlimb bud stage was significantly higher than that in the adult,and the proportion of Actinobacteria,Acidobacteria,Chloroflexi,Verrucomicrobia,Pseudomonas,Flavobacterium and Janthinobacterium in the adult was significantly higher than that in the hindlimb bud stage.There were some differences in the composition of skin microbiota in different habitats at the same developmental stage.The proportion of [Thermi] at the phylum level of forelimb bud stage in Shanding Lake was significantly higher than that in Zhuangyuan Bridge;the proportion of Actinobacteria,Firmicutes,Acidobacteria and Arcobacter in the hindlimb bud stage of Zhuangyuan Bridge was significantly higher than that of the Shanding Lake,and the proportion of Bacteroidetes in the hindlimb bud stage of the Shanding Lake was significantly higher than that of the Zhuangyuan Bridge;the proportion of Proteobacteria in adult of Zhuangyuan Bridge was significantly higher than that of Shanding Lake,and the proportion of Fusobacteria in adult of Shanding Lake was significantly higher than that of Zhuangyuan Bridge.In general,the composition of skin microbiota was affected by habitat disturbance,and the adaptive strategies of skin microbiota to habitat needed more research.Function prediction results showed that there were significant differences in the enrichment of functional pathways of skin microbiota at different developmental stages.In the forelimb bud stage,there was significant enrichment in environmental information processing pathway and human diseases pathway;the metabolism pathway was significantly enriched in the hindlimb bud stage;adult was significantly enriched in genetic information processing pathway.In conclusion,there were significant differences in the composition and structure of skin microbiota in different developmental stages of H.maoershanensis.The diversity of skin microbiota in adult was significantly higher than that in forelimb bud stage and hindlimb bud stage,and there was no significant difference in skin microbiota diversity between forelimb bud stage and hindlimb bud stage.The composition and structure of skin microbiota were also different in different habitats,and the diversity of skin microbiota in hindlimb bud stage was significantly different in different habitats.In general,the characteristics of skin microbiota could help it adapt to environmental changes in different developmental stages. |
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