Elevational Gradients Impose Dispersal Limitation on Streptomyces

Area of Science:

• Microbial Ecology
• Biogeography
• Genetics

Background:

• Dispersal is key to microbial biogeography, but its rates and mechanisms are poorly understood.
• Dispersal limitation arises from constraints on dissemination and establishment.
• Elevation gradients offer a powerful model for studying dispersal limitation due to steep environmental changes over small spatial scales.

Purpose of the Study:

• To investigate dispersal limitation in soil bacteria, specifically the genus Streptomyces, at local spatial scales.
• To assess the influence of elevation gradients on Streptomyces biogeography and community structure.
• To determine if habitat preferences and phylogenetic relatedness impact dispersal patterns.

Main Methods:

• Targeted a specific bacterial genus, Streptomyces, using the rpoB gene as a phylogenetic marker for higher resolution.
• Characterized Streptomyces diversity across local spatial scales (100-3,000 m) at two temperate forest sites with varying elevation changes (Woods Lake and Whiteface Mountain).
• Analyzed beta diversity patterns in relation to elevation and phylogenetic relatedness.

Main Results:

• Beta diversity of Streptomyces varied significantly at both sites, indicating dispersal limitation at local scales.
• Whiteface Mountain, with a larger elevation gradient, exhibited significantly higher beta diversity.
• Streptomyces taxa showed elevational preferences that were phylogenetically conserved, with lowest diversity at the mountain base.
• Habitat preferences and barriers to establishment appear to structure Streptomyces communities, especially at higher elevations.

Conclusions:

• Streptomyces biogeography is governed by dispersal limitation, influenced by both stochastic and deterministic processes.
• Phylogenetically conserved habitat preferences play a significant role in shaping soil microbial communities along elevation gradients.
• Barriers to establishment are critical factors structuring microbial communities in heterogeneous environments.