Background Hyperdiverse mtDNA with more than 5% of variable synonymous nucleotide sites can lead to erroneous interpretations of population genetic differentiation patterns and parameters (φST, DEST). We illustrate this by using hyperdiverse mtDNA markers to infer population genetic differentiation and connectivity in Melarhaphe neritoides, a NE Atlantic (NEA) gastropod with a high dispersal potential. We also provide a recent literature example of how mtDNA hyperdiversity may have misguided the interpretation of genetic connectivity in the crab Opecarcinus hypostegus. Results mtDNA variation surveyed throughout the NEA showed that nearly all M. neritoides specimens had haplotypes private to populations, suggesting at first glance a lack of gene flow and thus a strong population genetic differentiation. Yet, the bush-like haplotype network, though visually misleading, showed no signs of phylogeographic or other haplotype structuring. Coalescent-based gene flow estimates were high throughout the NEA, irrespective of whether or not mtDNA hyperdiversity was reduced by removing hypervariable sites. Conclusions Melarhaphe neritoides seems to be panmictic over the entire NEA, which is consistent with its long-lived pelagic larval stage. With hyperdiverse mtDNA, the apparent lack of shared haplotypes among populations does not necessarily reflect a lack of gene flow and/or population genetic differentiation by fixation of alternative haplotypes (DEST ≈ 1 does not a fortiori imply φST ≈ 1), but may be due to (1) a too low sampling effort to detect shared haplotypes and/or (2) a very high mutation rate that may conceal the signal of gene flow. Hyperdiverse mtDNA can be used to assess connectivity by coalescent-based methods. Yet, the combined use of φST and DEST can provide a reasonable inference of connectivity patterns from hyperdiverse mtDNA, too.
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RBINS Staff Publications 2019
Abstract This study compares histological preservation in archeological bones from different burial types to unravel the histotaphonomy-to-funerary practices relationship. Αn intraskeletal approach is also adopted to explore intraindividual (inner ear part of the petrous bone vs. upper/lower limb long bones) and intrabone (proximal vs. distal diaphysis) variability in bone collagen preservation, δ13C, and δ15N. The aim is to (a) target bones that likely retain higher amounts of collagen, (b) better understand the inner ear bone collagen isotopic signature and remodeling, and (c) assess intrabone isotopic and histological homogeneity. For the histological analysis, the data have been collected from 61 specimens (20 individuals) from the medieval/postmedieval cemetery of St. Rombout, Belgium. Thin sections have been studied using optical and scanning electron microscopy. For the collagen and isotopic data, 101 samples have been collected from 21 individuals. Distinct histological patterns are observed only in bones from single coffin burials; however, bone histology can display intraindividual and intrabone variability, which are important to account for interpretations. Collagen wt.%, δ13C, and δ15N show significant intraindividual differences but insignificant intrabone variability. This study also confirms the extraordinary nature of the petrous bone, as the inner ear bone collagen δ13C and δ15N values reflect the dietary input of the first approximately 2–3 years of life.
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RBINS Staff Publications 2022
