Highly polymorphic mitochondrial DNA and deceiving haplotypic differentiation: implications for assessing population...

Area of Science:

• Population Genetics
• Molecular Ecology
• Marine Biology

Background:

• Hyperdiverse mitochondrial DNA (mtDNA) with over 5% variable synonymous sites can lead to misinterpretations of population genetic differentiation.
• This study investigates the impact of mtDNA hyperdiversity on inferring population genetic patterns in the gastropod Melarhaphe neritoides.

Purpose of the Study:

• To illustrate how hyperdiverse mtDNA can mislead interpretations of population genetic differentiation and connectivity.
• To assess population genetic structure and gene flow in Melarhaphe neritoides using hyperdiverse mtDNA markers.
• To provide a literature example of similar issues in crab population genetics.

Main Methods:

• Analysis of mtDNA variation in Melarhaphe neritoides across the Northeast Atlantic.
• Construction of haplotype networks to visualize genetic diversity.
• Application of coalescent-based methods to estimate gene flow.
• Comparison of results with and without reduction of hypervariable mtDNA sites.

Main Results:

• Nearly all Melarhaphe neritoides specimens exhibited private haplotypes, initially suggesting strong population differentiation.
• Haplotype networks showed no phylogeographic structuring despite apparent hyperdiversity.
• Coalescent-based gene flow estimates indicated high connectivity across the Northeast Atlantic.

Conclusions:

• Melarhaphe neritoides appears panmictic across the Northeast Atlantic, consistent with its pelagic larval stage.
• Hyperdiverse mtDNA can mask gene flow signals due to high mutation rates or insufficient sampling.
• Coalescent methods are effective for assessing connectivity with hyperdiverse mtDNA, and combined use of φST and D_EST can aid inference.