Evolutionary process of a tetranucleotide microsatellite locus in Acipenseriformes

Area of Science:

• Evolutionary Biology
• Genetics
• Molecular Evolution

Background:

• Microsatellite loci are valuable for evolutionary studies.
• The tetra-nucleotide microsatellite locus Spl-106 is present in Acipenseriform species.
• Understanding microsatellite evolution requires analyzing both repeat and flanking sequences.

Purpose of the Study:

• To investigate the evolutionary dynamics of the Spl-106 microsatellite locus in Acipenseriform species.
• To analyze repeat and flanking sequence evolution using a novel phylogenetic method.
• To elucidate the mechanisms shaping microsatellite evolution, including duplication events.

Main Methods:

• Sequencing of the Spl-106 locus in 137 individuals from 15 Acipenseriform species.
• Application of the MS-Align phylogenetic method for sequence alignment and tree construction.
• Phylogenetic analysis of flanking and repeat regions to infer evolutionary patterns.

Main Results:

• Identified 93 homologous Spl-106 sequences across 11 species, with 23 flanking sequence haplotypes and three repeat types (I, II, III).
• Flanking regions were highly conserved among Acipenser, Huso, and Scaphirhynchus genera, diverging at 0.011%-0.079% per million years.
• MS-Align revealed synchronous evolution of flanking and repeat regions, clustering species into Pacific and Atlantic lineages.
• Two duplication events were inferred to explain the coexistence of different repeat types within species, particularly in the Pacific lineage.

Conclusions:

• The flanking and repeat regions of the Spl-106 locus exhibit synchronous evolutionary patterns.
• Duplication events are key mechanisms driving the diversity of repeat types within sturgeon species.
• The study provides insights into the complex evolutionary processes shaping microsatellite loci with multiple repeat types.