Background The metabolic cold-climate adaption hypothesis predicts that animals from cold environments have relatively high metabolic rates compared with their warm-climate counterparts. However, studies testing this hypothesis are sparse. Here, we compared gut microbes between two cold-climate lizard species of the genus Phrynocephalus to see if gut microbiota could help lizards adapt to cold environments by promoting metabolism. We conducted a 2 species (P. erythrurus and P. przewalskii) × 2 temperatures (24 and 30 °C) factorial design experiment, whereby we kept lizards of two Phrynocephalus species at 24 and 30 °C for 25 d and then collected their fecal samples to analyze and compare the microbiota based on 16S rRNA gene sequencing technology. Results The gut microbiota was mainly composed of bacteria of the phyla Proteobacteria, Firmicutes, Bacteroidetes, and Verrucomicrobia in both species (Proteobacteria > Firmicutes > Verrucomicrobiota in P. erythrurus, and Bacteroidetes > Proteobacteria > Firmicutes in P. przewalskii). Further analysis revealed that the gut microbiota promoted thermal adaptation in both lizard species, but with differences in the relative abundance of the contributory bacteria between the two species. An analysis based on the Kyoto Encyclopedia of Genes and Genomes revealed that the gut microbiota played important roles in metabolism, genetic information processing, cellular processes, and environmental information processing in both species. Furthermore, genes related to metabolism were more abundant in P. erythrurus at 24 °C than in other species ⋅ temperature combinations. Conclusion Our study provides evidence that gut microbiota promotes thermal adaptation in both species but more evidently in P. erythrurus using colder habitats than P. przewalskii all year round, thus confirming the role of gut microbiota in cold-climate adaptation in lizards.

Clarifying the genomic signatures, genes, and traits underlying local adaptation of organisms to their environments is a major goal in evolutionary biology. Local adaptation can generate genetic differentiation and divergence among populations, which may lead to reduced gene flow and eventually speciation (Merilä et al., 2004;Savolainen et al., 2013). Local adaptation across a landscape can disrupt patterns of isolation-by-distance (IBD) and result in patterns of isolation-by-environment (IBE; Sexton et al., 2014;Wang & Bradburd, 2014). Isolation-by-resistance (IBR), a modification of IBD, predicts that patterns of genetic divergence are explained by geographic distances accounting for variation in the degree of resistance to dispersal that organisms experience through heterogeneous landscapes (MacDonald et al., 2020;McRae, 2006). Studies of patterns of IBE, IBR, and IBD have facilitated our understanding of local adaptation in various organisms, such as the swallowtail butterfly Papilio machaon dodi (MacDonald et al., 2020) and Anolis

The metabolic cold-climate adaption hypothesis predicts that animals from cold environments have relatively high metabolic rates compared with their warm-climate counterparts. However, studies testing this hypothesis are sparse. Here, we compared gut microbes between two cold-climate lizard species of the genus Phrynocephalus to test the hypothesis that gut microbiota can help lizards adapt to cold environments by promoting metabolism and absorption efficiency. We kept lizards at 24°C and 30°C for 25 d, and then collected their fecal samples to analyze and compare the microbiota based on 16S rRNA gene sequencing technology. The gut microbiota was mainly composed of Proteobacteria, Firmicutes, Bacteroidetes, and Verrucomicrobia at the phylum level in both species (Proteobacteria > Firmicutes > Verrucomicrobiota in P. erythrurus, and Bacteroidota > Proteobacteria > Firmicutes in P. przewalskii). Further analysis revealed that the gut microbiota contributed to the host’s cold adaptation, but with differences in the relative abundance of these contributory bacteria between the two species. KEGG analysis revealed that the gut microbiota primarily played roles in metabolism, genetic information processing, cellular processes, and environmental information processing in both species. Furthermore, genes related to metabolism were more abundant in P. erythrurus at 24 °C than in other species × temperature combinations, indicating the role of gut microbiota in long-term cold-climate adaptation. Our finding that gut microbiome contributes to cold-climate adaptation in both species but more evidently in P. erythrurus using colder habitats than P. przewalskii throughout a year confirms the gut microbiota’s role in the cold-climate adaptation in lizards.

Background: The metabolic cold-climate adaption hypothesis predicts that animals from cold environments have relatively high metabolic rates compared with their warm-climate counterparts. However, studies testing this hypothesis are sparse. Here, we compared gut microbes between two cold-climate lizard species of the genus Phrynocephalus to test the hypothesis that gut microbiota can help lizards adapt to cold environments by promoting metabolism and absorption efficiency. We kept lizards at 24°C and 30°C for 25 d, and then collected their fecal samples to analyze and compare the microbiota based on 16S rRNA gene sequencing technology.Results: The gut microbiota was mainly composed of Proteobacteria, Firmicutes, Bacteroidetes, and Verrucomicrobia at the phylum level in both species (Proteobacteria > Firmicutes > Verrucomicrobiota in P. erythrurus, and Bacteroidota > Proteobacteria > Firmicutes in P. przewalskii). Further analysis revealed that the gut microbiota contributed to the host’s cold adaptation, but with differences in the relative abundance of these contributory bacteria between the two species. KEGG analysis revealed that the gut microbiota primarily played roles in metabolism, genetic information processing, cellular processes, and environmental information processing in both species. Furthermore, genes related to metabolism were more abundant in P. erythrurus at 24 °C than in other species ´ temperature combinations, indicating the role of gut microbiota in long-term cold-climate adaptation.Conclusion: Our study provides evidence that gut microbiome contributes to cold-climate adaptation in both species but more evidently in P. erythrurus using colder habitats than P. przewalskii throughout a year, thus confirming the gut microbiota’s role in the cold-climate adaptation in lizards.