An experimental test of Darwin's naturalization hypothesis

Area of Science:

• Ecology
• Evolutionary Biology
• Microbiology

Background:

• Darwin's naturalization hypothesis posits that introduced species succeed where their relatives are absent.
• Understanding invasion success is crucial for predicting ecological community dynamics.

Purpose of the Study:

• To experimentally test Darwin's naturalization hypothesis in bacterial communities.
• To investigate the role of phylogenetic relatedness in invasion success.

Main Methods:

• Laboratory experiments using bacterial communities with varying phylogenetic relatedness between resident and invading species.
• Inclusion and exclusion of a protist bacterivore to assess its impact.
• Analysis of invasion success, establishment frequency, and invader abundance.

Main Results:

• Invasion success increased with phylogenetic distance between invaders and residents, supporting the hypothesis.
• Phylogenetic distance to all residents predicted establishment frequency, suggesting niche limitation.
• Phylogenetic distance to the nearest relative predicted invader abundance, indicating optimal niche limitation.
• A specific resident bacterium (Serratia marcescens subspecies) showed strong resistance to an alien bacterium (another S. marcescens subspecies).

Conclusions:

• Phylogenetic relatedness is a significant predictor of species invasion success in microbial communities.
• Niche availability, both general and optimal, appears to be influenced by phylogenetic relatedness.
• The study provides experimental evidence for Darwin's naturalization hypothesis in a controlled microbial system.