Natural mating ability is associated with gut microbiota composition and function in captive male giant pandas

Abstract

The issue of poor sexual performance of some male giant pandas seriously impairs the growth and the genetic diversity of the captive population, yet there is still no clear understanding of the cause of the loss of this ability and its underlying mechanism. In this study, we analyzed the gut microbiota and its function in 72 fecal samples obtained from 20 captive male giant pandas, with an equal allocation between individuals capable and incapable of natural mating. Additionally, we investigated fecal hormone levels and behavioral differences between the two groups. A correlation analysis was then conducted among these factors to explore the influencing factors of their natural mating ability. The results showed significant differences in the composition of gut microbiota between the two groups of male pandas. The capable group had significantly higher abundance of Clostridium sensu stricto 1 (p _adjusted = .0021, GLMM), which was positively correlated with fatty acid degradation and two-component system functions (Spearman, p _adjusted < .05). Additionally, the capable group showed higher gene abundance in gut microbiota function including purine and pyrimidine metabolism and galactose metabolism, as well as pathways related to biological processes such as ribosome and homologous recombination (DEseq2, p _adjusted < .05). We found no significant differences in fecal cortisol and testosterone levels between the two groups, and no difference was found in their behavior either. Our study provides a theoretical and practical basis for further studying the behavioral degradation mechanisms of giant pandas and other endangered mammal species.

Keywords: behavior; breeding; genetic diversity; giant panda; gut microbiota; hormone.

FIGURE 1

Captive giant pandas engaging in natural mating at RCQGP.

FIGURE 2

Gut microbiota diversity and hierarchical clustering of captive male giant pandas. (a) Alpha diversity levels represented by Richness, Shannon, and Pielou's evenness diversity indices, with different letters indicating significant differences (p < .05). (b) Beta diversity PCoA plot based on Bray–Curtis distance and intergroup Adonis dissimilarity index. p < .05 indicates significant differences. (c) Hierarchical clustering circle tree, where each node represents a taxonomic unit, and the branch length indicates the degree of variation within the corresponding species.

FIGURE 3

Composition of gut microbiota in captive male giant pandas. Composition of microbial phyla (a) and genera (b) between the capable and incapable groups. (c) We performed a difference analysis at the genus level between the two groups and used an extended error bar plot in the style of Statistical Analysis of Metagenomic Profiles (STAMP) for visualization. The top 30 differentially abundant genera with significant differences are shown. The left side displays a bar plot comparing the average abundance between groups, and the right side shows scatter plots of the average abundance and 95% confidence intervals. The p _adjusted values were all <.05.

FIGURE 4

Differential prediction of gut microbiota gene functions between capable and incapable male giant pandas. The bar plot on the left represents the top 30 KEGG pathways with significant differences in relative abundance (p _adjusted < .05). The fold change plot on the right illustrates the differential changes between the two groups.

FIGURE 5

The correlation between the gut microbiota and gene predicted functions in captive adult male giant pandas. For data readability, only the top 30 features with an absolute correlation value >.7 are displayed. All data nodes can be found in Appendix S5. The correlations were calculated using Spearman's rank correlation coefficient, and significance was determined with a p _adjusted value of <.05. The size of the nodes represents the relative abundance, with larger nodes indicating higher abundance.

FIGURE 6

Differences in (a) cortisol and testosterone levels and (b) behaviors between the capable group and incapable group of giant pandas for natural mating. “ns” indicates non‐significant differences.