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Selfish drive can trump function when animal mitochondrial genomes compete
Hansong Ma1, Patrick H O'Farrell1
1Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, USA.
Nature Genetics
|June 9, 2016
Summary
Mitochondrial genomes compete during inheritance. Closely related genomes face purifying selection, while distantly related ones can exhibit selfish selection, sometimes harming the host.
Area of Science:
- Genetics
- Evolutionary Biology
- Mitochondrial Biology
Background:
- Mitochondrial genomes are maternally inherited and essential for cellular respiration.
- Competition among mitochondrial genomes within a cell can influence their transmission to offspring.
- Understanding these competitive dynamics is crucial for comprehending mitochondrial evolution and disease.
Purpose of the Study:
- To investigate the competitive dynamics between different mitochondrial genomes within a single organism.
- To determine the factors driving selection during mitochondrial genome competition.
- To identify the genetic elements responsible for selfish mitochondrial genome transmission.
Main Methods:
- Introducing a second, distinct mitochondrial genome into Drosophila melanogaster.
- Monitoring the transmission patterns of competing mitochondrial genomes across generations.
- Sequencing recombinant mitochondrial genomes to identify regions associated with transmission bias.
Main Results:
- Competition between closely related mitochondrial genomes favors functional genomes (purifying selection).
- Distantly related mitochondrial genomes can exhibit selfish selection, leading to detrimental outcomes for the host.
- A non-coding region, including replication origins, was identified as governing selfish transmission.
- Stable coexistence of two competing mitochondrial genomes was observed when selfish and purifying selection balanced.
Conclusions:
- Mitochondrial genome competition is a significant evolutionary force, shaped by both host benefit and selfish genetic elements.
- Selfish selection can override purifying selection, potentially leading to host detriment.
- The non-coding regions of mitochondrial genomes play a key role in regulating transmission dynamics and promoting the evolution of super-replicators.
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