Evolution along the mutation gradient in the dynamic mitochondrial genome of salamanders

Area of Science:

• Evolutionary biology
• Genomics
• Molecular biology

Background:

• Mitochondria possess their own genome crucial for ATP synthesis.
• Gene rearrangement is common in invertebrates, linked to higher substitution rates.
• Vertebrate mitochondrial gene rearrangement is rare, with its impact on substitution rates unexplored.

Purpose of the Study:

• Investigate the effects of large-scale mitochondrial genome architecture changes on vertebrate gene evolution.
• Determine if mitochondrial gene rearrangement impacts substitution rates and mutation gradients in vertebrates.
• Assess the relationship between genomic modifications and selective constraints on mitochondrial genes.

Main Methods:

• Comparative analysis of mitochondrial genomes in salamanders with normal, rearranged, and expanded architectures.
• Examination of gene substitution rates and their spatial variation along the mitochondrial DNA mutation gradient.
• Assessment of selective constraint levels on mitochondrial genes in relation to genomic rearrangements.

Main Results:

• Rearranged and expanded mitochondrial genomes exhibit higher substitution rates.
• Most genes in modified genomes retain their positions along a weak mutation gradient.
• Gene substitution rates are unaffected by positional changes, and rearrangements are independent of selective gene constraints.

Conclusions:

• Large-scale mitochondrial genome architecture changes significantly impact gene evolution in vertebrates.
• Despite architectural changes, functional constraints on mitochondrial protein-coding genes remain consistent across normal and modified genomes.
• The study reveals predictable patterns in mitochondrial gene evolution influenced by genome structure.