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Published on: March 16, 2014
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Comparative Mitogenomics in Hyalella (Amphipoda: Crustacea)
Francesco Zapelloni1, José A Jurado-Rivera1, Damià Jaume2
1Department of Biology, University of the Balearic Islands, Ctra. Valldemossa km 7,5, 07122 Palma, Spain.
Genes
|March 6, 2021
Summary
This study sequenced 17 Hyalella amphipod mitochondrial genomes, revealing gene rearrangements and significant base changes in tRNA stems. These findings suggest evolutionary adaptations in Hyalella populations.
Area of Science:
- Evolutionary Biology
- Genomics
- Molecular Biology
Background:
- Mitochondrial genomes (mitogenomes) are crucial for understanding evolutionary processes in crustaceans.
- The amphipod genus Hyalella, particularly from the Andean Altiplano, offers a unique system for studying evolutionary divergence.
- Previous studies highlight the AT-richness and strand biases typical of pancrustacean mitogenomes.
Purpose of the Study:
- To sequence and comparatively analyze 17 mitochondrial genomes of Nearctic and Neotropical Hyalella amphipods.
- To investigate gene rearrangements and nucleotide biases within Hyalella mitogenomes.
- To examine base changes in tRNA stems and identify potential evolutionary adaptations.
Main Methods:
- Sequencing of 17 mitochondrial genomes from Hyalella species.
- Comparative genomic analysis focusing on gene content, arrangement, and nucleotide composition.
- Analysis of base changes in tRNA stems, including compensatory and hemi-compensatory mutations.
- Application of branch-site models to detect positive selection in mitochondrial genes.
Main Results:
- The 37-gene set metazoan mitochondrial genome structure was confirmed, with notable gene rearrangements (reverse transposition and reversal) between North and South American Hyalella.
- Hyalella mitogenomes exhibit typical AT-richness and strand biases, with protein-coding sequences favoring AT-rich codons (leucine, serine).
- Extensive base changes (539) were observed in tRNA stems, including 103 fully compensatory and 253 hemi-compensatory mutations, suggesting adaptation to maintain tRNA structure and function.
- Positive selection was detected at multiple amino acid positions in up to eight mitochondrial genes, particularly atp6 and nad5.
Conclusions:
- Mitochondrial genome sequencing reveals significant gene rearrangements and nucleotide biases in Hyalella, reflecting evolutionary divergence between Nearctic and Neotropical lineages.
- Compensatory and hemi-compensatory base changes in tRNA stems suggest adaptive mechanisms to maintain pairing stability and function, potentially overcoming fitness valleys.
- Evidence of positive selection in key mitochondrial genes (atp6, nad5) indicates ongoing adaptive evolution within Hyalella populations.
