Lichen holobionts show compositional structure along elevation

Area of Science:

• Ecology
• Microbiology
• Symbiosis research

Background:

• Holobionts are complex ecosystems where microbial communities interact with host organisms.
• Understanding how these microecosystems respond to environmental gradients is crucial for ecological insights.
• Lichens, as symbiotic associations, offer a model system to study holobiont dynamics.

Purpose of the Study:

• To investigate the collective response of lichen holobiont components (fungal, algal, bacterial) to an elevational gradient.
• To identify diversity patterns and community shifts within lichen holobionts across different altitudes and biomes.
• To determine if lichen holobionts exhibit similar environmental responses as larger organisms.

Main Methods:

• Analysis of fungal host, algal symbiont, and bacterial community composition in lichen populations along an elevational gradient (2100m).
• Genomic variation assessment of fungal hosts.
• Community structure analysis of bacterial symbionts and identification of algal symbionts.
• Correlation of holobiont composition with climatic factors (temperature) and altitudinal belts.

Main Results:

• Fungal hosts exhibited discontinuous genomic variation with abrupt differentiation.
• Bacterial communities were altitudinally structured, showing significant turnover within and between hosts.
• Bacterial alpha diversity decreased with increasing elevation.
• Distinct altitudinal belts (800-1200m and 1500-1800m) showed marked turnover in holobiont diversity.
• Holobiont composition aligned with Mediterranean, cool-temperate, and alpine climate zones.

Conclusions:

• Lichen holobionts demonstrate concerted compositional changes in response to elevational and climatic gradients.
• These microecosystem responses are analogous to those observed in macroorganism communities, such as vascular plants.
• Climatic factors play a significant role in structuring multitrophic microecosystems like lichens.