Browsing by Author "Wells, Jeffrey D."

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    Amplified fragment length polymorphism analysis supports the valid separate species status of Lucilia caesar and L. illustris (Diptera: Calliphoridae)
    (Taylor & Francis:, 2017-12-08) Picard, Christine J.; Wells, Jeffrey D.; Ullyot, Anne; Rognes, Knut; Biology, School of Science
    Common DNA-based species determination methods fail to distinguish some blow flies in the forensically and medically important genus Lucilia Robineau-Desvoidy. This is a practical problem, and it has also been interpreted as casting doubt on the validity of some morphologically defined species. An example is Lucilia illustris and L. caesar, which co-occur in Europe whilst only L. illustris has been collected in North America. Reports that these species shared both mitochondrial and nuclear gene sequences, along with claims that diagnostic morphological characters are difficult to interpret, were used to question their separate species status. We report here that amplified fragment length polymorphism profiles strongly support the validity of both species based on both assignment and phylogenetic analysis, and that traditional identification criteria based on male and female genital morphology are more reliable than has been claimed.
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    Molecular Genetic Methods for Forensic Entomology
    (CRC Press, 2019) Stevens, Jamie R.; Picard, Christine J.; Wells, Jeffrey D.
    A preservative solution containing formaldehyde should not be used if it can be avoided, as formalin can interact with deoxyribonucleic acid (DNA), making subsequent molecular analyses difficult. Some forensic entomologists recommend killing maggots by blanching in hot water; this technique does not appear to hinder any subsequent DNA analysis. Maggots found in the absence of a corpse may still have the victim’s tissue in their gut. Such specimens must be killed and preserved immediately, otherwise the evidence may be digested and lost. There is little doubt about the need for accurate specimen identification in forensic entomology. Intraspecific variation in DNA sequence is commonly observed, so an unknown specimen will often not exactly match the genotype of a reference specimen. Ribonucleic acid analysis can reveal the genes that were active within a tissue sample at the time it was processed.