Abstract
We characterized variation within the mitochondrial genomes of the invasive silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) from the Mississippi River drainage by mapping our Next-Generation sequences to their publicly available genomes. Variant detection resulted in 338 single-nucleotide polymorphisms for H. molitrix and 39 for H. nobilis. The much greater genetic variation in H. molitrix mitochondria relative to H. nobilis may be indicative of a greater North American female effective population size of the former. When variation was quantified by gene, many tRNA loci appear to have little or no variability based on our results whereas protein-coding regions were more frequently polymorphic. These results provide biologists with additional regions of DNA to be used as markers to study the invasion dynamics of these species.

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Acknowledgments
We would like to thank Duane Chapman, U.S. Geological Survey, for providing tissue samples and Joe Boland and Dave Roberson, National Cancer Institute, for providing access to the Ion Torrent Proton sequencing platform. In addition, we would like to acknowledge Jim Grazio of the Pennsylvania Department of Environmental Protection and Sharon Gross of the U.S. Geological Survey Ecosystems Mission Area Invasive Species Program for funding this project. We wish to thank Dolly Coykendall for providing useful comments on an earlier version of the manuscript. Use of trade, product, or firm names does not imply endorsement by the U.S. Government.
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Miller, J.J., Eackles, M.S., Stauffer, J.R. et al. Next-generation genomic shotgun sequencing indicates greater genetic variability in the mitochondria of Hypophthalmichthys molitrix relative to H. nobilis from the Mississippi River, USA and provides tools for research and detection. Conservation Genet Resour 7, 9–11 (2015). https://doi.org/10.1007/s12686-014-0296-3
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DOI: https://doi.org/10.1007/s12686-014-0296-3