ECOLOGICAL DIFFERENTIATION OF AMINO ACID STABLE ISOTOPE PROFILES REVEALS MICROBIAL CONTRIBUTIONS TO PROTEIN METABOLISM IN WILD SMALL MAMMAL COMMUNITIES
Abstract
Amino acid stable isotope analysis offers an effective method to study ecological differentiation and metabolic differences within hosts in wildlife systems. Gut microbes can play a role in protein metabolism; however, there is limited information about their isotopic discrimination relative to mammals. The present study aimed to evaluate ecological differentiation in amino acid stable isotope profiles among wild small mammal groups and associated fecal microbial communities. A
quantitative secondary-data design was applied to 70 observations containing ecological group information and amino acid carbon and nitrogen isotope variables. Non-detectable values were treated as missing data, isotope variables were converted into numeric format, and standardized values were used for multivariate analysis. Descriptive statistics, correlation analysis, principal component analysis, and analysis of variance were performed to assess isotopic structure and group-level differences. Stable isotope variables showed a clear multivariate structure. PC1 explained 41.999% of the total variance, while PC2 and PC3 explained 25.602% and 6.654%, respectively. Significant group differences were
observed for PC1 (F = 34.545, p < 0.001) and PC3 (F = 18.845, p < 0.001), whereas PC2 was not significant. Carbonassociated amino acid markers, especially Leu13C, Glx13C, Ile13C, Val13C, and Pro13C, contributed most strongly to ecological separation. Amino acid isotope profiles distinguished mammalian groups from fecal microbial communities and highlighted the importance of carbon-linked metabolic pathways in ecological differentiation.
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