Pitfalls in applying mitochondrial markers onto the scolytid species Pityogenes chalcographus

Publication Type:Journal Article
Authors:W. Arthofer, Avtzis, D. N., Riegler, M., Miller, W. J., Stauffer, C.
Journal:U S Forest Service Rocky Mountain Research Station Proceedings RMRS-P
Date Published:June
:Pityogenes chalcographus

Pityogenes chalcographus is one of the major pests in Eurasian spruce stands. Crossing experiments performed in the mid-1970s suggested race differentiation, and mtDNA analysis of P. chalcographus gave evidence that today's populations are divided into several clades. The genetic distance between clades favours a model of allopatric origin with a separation about one million years ago while today haplotypes of the major clades exist sympatrically all over Europe. Within the last few years, the use of mtDNA as a sole genetic marker became a matter of critical discussion. It was shown that nuclear copies of mtDNA (numts) led to artefacts in some of the derived genealogies. A long PCR based approach for elimination of potential numt sequences was developed to validate the dataset of P. chalcographus. This method showed that the beetle's genome does not contain numts. Another factor that may influence mitogenomes is the presence of endosymbiotic Wolbachia, which causes alterations in insect reproduction and thus influences the population's mtDNA patterns. While Wolbachia was not found in P. chalcographus in past studies, the use of long and nested PCR, cloning and sequencing of PCR products, and in situ hybridization techniques gave evidence that at least a certain percentage of European populations harbour this intracellular endosymbiont. An influence on the mitochondrial dataset can not be excluded and further research is proposed to estimate the prevalence of Wolbachia in P. chalcographus.

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