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Microsatellite evolution: Mutations, sequence variation, and homoplasy in the hypervariable avian microsatellite
Jarl A Anmarkrud1, Oddmund Kleven, Lutz Bachmann
1National Centre for Biosystematics, Natural History Museum, University of Oslo, P,O, Box 1172 Blindern, NO-0318 Oslo, Norway. j.a.anmarkrud@nhm.uio.no
BMC Evolutionary Biology
|May 13, 2008
Summary
Microsatellite evolution is influenced by length and interrupting motifs. Longer microsatellites show more mutations, but interrupting motifs stabilize them, cautioning against fragment length analysis for genetic diversity.
Area of Science:
- Genetics
- Evolutionary Biology
- Bioinformatics
Background:
- Microsatellites are valuable genetic markers due to high polymorphism.
- Understanding microsatellite evolution, particularly the role of interrupting motifs, is crucial.
- This study analyzes mutation events and repeat structures in swallow microsatellites.
Purpose of the Study:
- To investigate microsatellite mutation events and structural characteristics.
- To explore the relationship between microsatellite length, interrupting motifs, and stability.
- To assess the impact of size homoplasy in microsatellite analysis.
Main Methods:
- Sequence analysis of microsatellite loci (HrU10) in barn and tree swallows.
- Screening for mutations (loss/gain of repeat units) in parent-offspring data.
- Correlating microsatellite length and interrupting motif characteristics with mutation rates.
Main Results:
- Detected mutations involving one or two repeat units in both swallow species.
- Replication slippage identified as the primary mutational process.
- Found a positive correlation between microsatellite length and interrupting motif occurrence.
- Identified a threshold for perfect repeat length, beyond which stability decreases.
- Observed significant size homoplasy in mutated alleles.
Conclusions:
- Microsatellite slippage rate increases with length.
- Interrupting motifs stabilize microsatellite regions composed of perfect repeats.
- Size homoplasy in hypervariable microsatellites necessitates caution when using fragment length analysis for genetic diversity.
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