Seasonal Variations in the Gut Fungal Communities of Hooded Crane (Grus monacha) at Wintering and Stopover Sites in China

Abstract

The "gut fungal microbiome" maintains the immune system, homeostasis, and various physiological functions of an organism. Different factors shape and affect gut fungal diversity and community composition, such as environment, habitat type, food resources, and seasons during migration. Wild birds amid migration are exposed to different habitats with different environments, available food resources, and seasons, which may substantially impact their gut fungal community composition and diversity. The hooded crane (Grus monacha) is a known migratory bird that migrates over long distances and is exposed to varied habitats with different environments and food types. We investigated the differences in gut fungal diversity and community composition between wintering and stopover sites amid three migratory seasons. We deduced the gut fungal pathogenic diversity and community composition during winter, fall, and spring by using high throughput sequencing (Illumina Mi-seq), and the internal transcribed region 2 (ITS2) was examined. Samples were collected from Shengjin Lake in the winter and Lindian during the fall and spring. The dominant fungal phyla found across the three seasons were Ascomycota, Basidiomycota, Zygomycota, and Rozellomycota. The gut fungal alpha diversity showed significant shifts during winter at the wintering site compared with the fall and spring seasons at the stopover site. The fungal community composition exhibited a significant change across the three seasons (ANOSIM p = 0.001). The results also demonstrated that the diversity and relative abundance of potential pathogens also showed divergence in winter compared to fall and spring. This study provides the basis for understanding the discrepancy in gut fungal diversity and community composition during migratory seasons at both wintering and stopover grounds. It also suggests that conservation measures should be applied to the conservation of hooded cranes and other wild birds, as the risk of cross-infection increases during seasonal migration.

Keywords: fungi; high-throughput sequencing; hooded crane; migration; pathogens; seasonality.

Figure 1

Area of fecal sample collection of the hooded crane from (A) Shengjin Lake and (B) Lindian.

Figure 2

Analysis indicates the unique and common gut fungal operational taxonomic units (OTUs) of the hooded crane during fall, winter, and spring using a Venn diagram.

Figure 3

Gut fungal alpha diversity of the hooded crane during three seasons. (A) Operational taxonomic unit (OTU) richness, and (B) Chao 1. Bars exhibit mean value; error bars exhibit standard deviation; the different letters ‘’a’’ and ‘’b’’ over the bars represent significant differences from one-way ANOVA by applying Tukey’s Honest Significant Difference HSD test (p < 0.05). OTU, operational taxonomic unit.

Figure 4

The relative abundance of the dominant gut fungal phyla of the hooded crane in fall, winter, and spring. (A) Ascomycota, (B) Basidiomycota, (C) Zygomycota, and (D) Rozellomycota. The different letters ‘’a’’, ‘’b’’ over bars represent significant differences in Tukey’s HSD comparisons (p < 0.05). Bars represent mean; error bars indicate standard deviation.

Figure 5

Linear discriminant analysis (LDA) effect size (LEfSe) analysis of the gut fungal biomarker of the hooded crane during fall, winter, and spring. Cladogram exhibits the biomarkers with the hierarchical taxonomic structure identified during three seasons. Evaluated biomarkers were ranked by effect size (LDA > 2, p < 0.05). Red phylotypes represent in fall; green phylotypes represent in spring; blue phylotypes represent in winter.

Figure 6

Gut fungal community structure of the hooded crane by applying non- metric multidimensional scaling (NMDS) amid fall, winter, and spring.

Figure 7

The potential gut fungal pathogenic OTU richness and community composition of the hooded crane during fall, winter, and spring. (a) Operational taxonomic unit (OTU) richness, and (b) analysis of similarity (ANOSIM) and Kruskal–Wallis Test. Different letters “a” and “b” represent significant differences (p < 0.05).

Figure 8

Analysis of the Venn diagram showing the unique and shared gut pathogenic fungal operational taxonomic units (OTUs) of the hooded crane during fall, winter, and spring.