Wild Butterfly Microbiota Shows Gradual Shifts and Resilience Over 28 Years of Climate Change
A study of the Glanville fritillary butterfly in Finland found that its larval bacterial communities changed gradually over 28 years of warming and drying conditions, and were severely disrupted by a 2018 extreme drought. Researchers used 16S rRNA metabarcoding and metagenomic sequencing on a well-documented long-term field population in the Åland Islands. The findings suggest wild insect microbiomes are sensitive to both slow climate trends and acute weather extremes, with potential fitness consequences for host species.
Researchers analyzed bacterial communities associated with larvae of the Glanville fritillary butterfly (Melitaea cinxia) across a 28-year period using archived and contemporary samples from a long-monitored metapopulation in the Åland Islands, Baltic Sea. Using 16S rRNA metabarcoding and metagenomic sequencing, they identified a stable core microbiome including Pseudomonas, Telluria, and Enterobacteriaceae, but also documented a gradual compositional shift corresponding to rising temperatures and declining precipitation over three decades. Notably, the dominant bacterial taxa did not respond uniformly: Telluria and Pseudomonas showed opposing trends in response to environmental change. The 2018 extreme drought, which caused acute population bottlenecks in the butterfly host, was associated with a severe disruption of the microbiome and the loss of key Enterobacteriaceae taxa. Importantly, the bacterial community appeared to recover toward its pre-drought composition in subsequent years, indicating some degree of resilience to acute climatic perturbations. Because host-associated microbes support metabolism, immunity, and nutrition, these community shifts may carry meaningful fitness consequences for the butterfly population.
What's missing
The study does not clarify whether the observed microbiome shifts have been directly linked to measurable changes in butterfly fitness, survival, or reproduction in the field. It is also unclear how much of the microbiome variation is driven by host genetic changes during population bottlenecks versus direct environmental effects on microbial communities.
What different sources said
- bioRxivCenter
The microbiota of a wild butterfly species over three decades of climate change
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