Related Experiment Video
Updated: May 5, 2026
07:43
Coincubation Assay for Quantifying Competitive Interactions between Vibrio fischeri Isolates
Published on: July 22, 2019
7.9K
Evolutionary origins and diversification of proteobacterial mutualists
Joel L Sachs1, Ryan G Skophammer, Nidhanjali Bansal
1Department of Biology, University of California, , Riverside, CA 92521, USA, Department of Plant Pathology and Microbiology, University of California, , Riverside, CA 92521, USA, Institute for Integrative Genome Biology, University of California, , Riverside, CA 92521, USA.
Proceedings. Biological Sciences
|November 29, 2013
Summary
Mutualistic bacteria frequently originate from parasitic ancestors, with their traits rarely driving diversification. This study reveals surprising origins and evolutionary conservatism in bacterial mutualisms.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genomics
Background:
- Mutualistic bacteria are widespread across eukaryotic species and biomes.
- Key questions persist regarding the origin of mutualist bacterial phenotypes and their impact on diversification.
Purpose of the Study:
- To investigate the origins and evolutionary diversification of mutualistic bacterial phenotypes within the Proteobacteria phylum.
- To determine the frequency of mutualist phenotype evolution and its effect on bacterial diversification rates.
Main Methods:
- Phylogenetic reconstruction of the Proteobacteria phylum.
- Ancestral state reconstructions (ASRs) to infer the evolutionary history of mutualistic traits.
Main Results:
- Identified 34-39 independent origins of mutualistic phenotypes in Proteobacteria.
- Found mutualists frequently evolved from parasitic ancestors, not free-living ones.
- Inferred a negative net diversification rate for mutualists, indicating evolution via transitions rather than diversification within mutualism.
Conclusions:
- Mutualistic bacterial phenotypes arise frequently and often from parasitic lineages.
- Mutualism appears evolutionarily conservative, with limited reversals and low diversification within mutualist clades.
- Findings challenge long-standing theories on the evolutionary dynamics of microbial mutualisms.
Related Concept Videos
01:25Microbial Interactions: Mutualism
93
Mutualism is a symbiotic interaction in which all participating organisms benefit. These relationships can be obligate or facultative and are fundamental to ecosystem functions across diverse biological systems.Plant–Fungi MutualismOne well-known example is the association between plant roots and mycorrhizal fungi, such as Rhizophagus species. The fungal hyphae penetrate the root hairs and the epidermis, forming an extensive hyphal network that establishes a symbiotic association. Through...
93
01:24Evolution of New Traits in Microbes
201
Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
201
01:26Bacterial Phylum Proteobacteria
1.1K
Proteobacteria, one of the largest and most diverse bacterial phyla, encompasses a wide range of Gram-negative bacteria distinguished by their outer membrane composed of lipopolysaccharides. These microorganisms exhibit various metabolic capabilities, including phototrophy, chemolithotrophy, and heterotrophy, and thrive in diverse environments from soil to aquatic systems and host-associated niches. The phylum is divided into six classes: Alphaproteobacteria, Betaproteobacteria,...
1.1K
01:18Deep Sea Microbial Ecology
55
The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The photic (euphotic) zone typically spans the upper ~100–200 meters of pelagic waters in the open ocean, but its depth varies geographically and seasonally, where sufficient light supports photosynthetic life. Below this lies the deep sea, spanning roughly 1000–6000 meters (bathypelagic to abyssal zones), with deeper hadal trenches...
55
01:26Microbial Interactions: Competition
94
Microbial competition is an ecological interaction in which microorganisms vie for limited resources within shared environments. These resources may include nutrients, space, or light, depending on the system. The intensity and outcome of competition are influenced by the environmental context, such as nutrient availability, spatial constraints, and the diversity of microbial species present. These competitive interactions significantly influence the structure, function, and resilience of...
94
01:15Diversity of Protists I
2.3K
Excavata is a diverse group of protists that includes both chemoorganotrophic and phototrophic species, with some thriving in anaerobic environments. Among the key groups within Excavata are diplomonads and parabasalids, which are flagellated protists that lack mitochondria and chloroplasts. These microorganisms typically inhabit anoxic environments, such as the intestines of animals, where they exist either symbiotically or as parasites, relying on fermentation for energy production. Some...
2.3K