A microbial view on secondary contact between two Alpine butterflies.

Area of Science:

• Ecology
• Microbiology
• Evolutionary Biology

Background:

• Sibling species often face limited sympatry if ecologically too similar.
• Ecological niche is typically assessed via abiotic factors, overlooking biotic components like gut microbes.
• This study investigates gut microbial communities as a proxy for biotic niche differentiation in two closely related Alpine butterfly species.

Purpose of the Study:

• To explore gut microbial community differences between two sympatric Erebia butterfly species.
• To assess the role of gut microbiota in ecological niche differentiation during secondary contact.
• To determine if gut microbial composition reflects local adaptation or habitat specialization.

Main Methods:

• Metabarcoding of adult gut microbial communities in two focal Erebia species.
• Analysis of microbial diversity on associated nectar plant species.
• Comparison of microbial community structures between species, sexes, and environmental samples.

Main Results:

• Gut microbial communities significantly differed between the two butterfly species, irrespective of sex.
• The abundance of the endosymbiont Wolbachia varied between species, impacting overall microbial diversity detected.
• Microbial overlap between butterfly hosts and nectar plants was partial, suggesting some environmental filtering within the gut.

Conclusions:

• Species-specific gut microbial communities support biotic niche differentiation in these Erebia butterflies.
• Gut microbiota composition may reflect adaptation to different resources or microhabitats.
• Gut microbial metabarcoding is a valuable tool for studying ecological niche differentiation, even in secondary contact zones.