3.6 Variation in gut fungal communities of giant pandas with
different lifestyles
A total of 4,362,547 fungal ITS sequences were obtained from samples in
the lifestyle shift experiments. After removal of mitochondria and
chloroplast sequences, 4,218,492 ITS sequences were clustered into 7,438
OTUs at the 97% sequence identity threshold. Fungal community richness
was significantly higher in the GM of reintroduced and wild pandas
compared to those of wild-training I and wild-training II (p< 0.05, ANOVA test) (Figure 3a). The fungal diversity of
wild-training I panda communities was significantly lower than in those
of other three groups (p < 0.05, ANOVA test) (Figure
3b). PCoA indicated that fungal communities from hosts with the same
lifestyle clustered together and separately from others (Figure 3c).
Ascomycota and Basidiomycota were the dominant phyla of fungal
communities in the lifestyle shift experiments regardless of lifestyle,
although their abundances varied by lifestyle (Non-parametric factorial
Kruskal-Wallis sum-rank test, LDA>4) (Figure 3d, e).
Ascomycota had notably higher relative abundances in wild-training I
panda gut communities (92.4%), while Basidiomycota were more abundant
in wild-training II (33.4%) pandas (Non-parametric factorial
Kruskal-Wallis sum-rank test, LDA>4) (Figure 3e). At the
genus level, Candida (83.1%) was the most dominant genus in
wild-training I panda communities and were significantly more abundant
than in wild-training II (3.2%) and reintroduced (2.8%) pandas,
followed by Williopsis (2.7%) and Cryptococcus (0.7%)
(Non-parametric factorial Kruskal-Wallis sum-rank test,
LDA>4) (Figure 3e, f). Cryptococcus (12.3%),Shiraia (10.3%), and Cystofilobasidium (8.1%) were the
most abundant genera in the wild-training II panda gut communities.
Further, the abundances of Cryptococcus (12.3%),Cystofilobasidium (8.1%), Purpureocillium (3.8%), andPenicillium (2.5%) were significantly higher in wild-training II
panda communities than in those of wild-training I (0.7%, 0.7%,
0.06%, and 0.09%, respectively) and reintroduced (3.2%, 0.6%, 0.1%,
and 1.0%, respectively) pandas (Non-parametric factorial Kruskal-Wallis
sum-rank test, LDA>4). Mrakiella (9.2%),Phoma (8.3%), and Verticillium (4.9%) were the most
abundant genera in the reintroduced pandas. The abundances ofMrakiella (9.2%) were significantly higher in the reintroduced
panda communities relative to the wild-training I (0.1%) and
wild-training II (0.7%) pandas (Non-parametric factorial Kruskal-Wallis
sum-rank test, LDA>4).
Although the gut fungal community compositions in the reintroduced and
wild pandas were more similar to each other than they were to those of
the wild-training I and wild-training II pandas, significant genus level
differences were observed between the reintroduced and wild panda
communities (p < 0.05, Wilcoxon test). Specifically, 11
genera were significantly different between reintroduced and wild panda
communities (excluding unidentified genera), including Candidaand Calycina which were among the 10 most abundant genera
(Supplementary Figure 2). Candida (2.8%) were more abundant in
reintroduced pandas, while Calycina (13.2%) was more abundant in
wild pandas (p < 0.05, Wilcoxon test).