Utility of Multi-Gene Loci for Forensic Species Diagnosis of Blowflies

Abstract

Contemporary studies in forensic entomology exhaustively evaluate gene sequences because these constitute the fastest and most accurate method of species identification. For this purpose single gene segments, cytochrome oxidase subunit I (COI) in particular, are commonly used. However, the limitation of such sequences in identification, especially of closely related species and populations, demand a multi-gene approach. But this raises the question of which group of genes can best fulfill the identification task? In this context the utility of five gene segments was explored among blowfly species from two distinct geographic regions, China and Pakistan. COI, cytochrome b (CYTB), NADH dehydrogenase 5 (ND5), nuclear internal transcribed spacers (ITS1 and ITS2), were sequenced for eight blowfly species including Chrysomya megacephala F. (Diptera: Calliphoidae), Ch. pinguis Walker, Lucilia sericata Meigen L. porphyrina Walker, L. illustris Meigen Hemipyrellia ligurriens Wiedemann, Aldrichina grahami Aldrich, and the housefly, Musca domestica L. (Muscidae), from Hangzhou, China; while COI, CYTB, and ITS2 were sequenced for four species, i.e. Ch. megacephala, Ch. rufifacies, L. cuprina, and the flesh fly, Sarcophaga albiceps Meigen (Sarcophagidae), from Dera Ismail Khan Pakistan. The results demonstrate a universal utility of these gene segments in the molecular identification of flies of forensic importance.

Reliability of long vs short COI markers in identification of forensically important flies

“…This pattern of evolution was also observed previously based on 28rRNA alone (36) and based on COI, CYTB, and ITS2 in a multi-gene approach (16). This relation was different from that observed based on 272-bp COI, when A. grahami was embedded within Lucilia tribe.…”

Phenotypic polymorphism of Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) may lead to species misidentification

“…Comparing all genetic regions and methods utilized, the results presented agree with the assumption that a multigene approach is stronger than single gene analyses (Stevens et al, 2002;Wallman et al, 2005;McDonagh and Stevens, 2011;Zaidi et al, 2011;Nelson et al, 2012) leading to more robust and unambiguous conclusions. The distance method, the phylogenetic topologies, and the likelihood-map results are in agreement with previous observations (Zumpt, 1965;Tantawi and Greenberg, 1993) that the isolated proepimeral seta, in fact, is a weak morphological diagnostic character to differentiate C. albiceps from C. rufifacies, since a few C. albiceps individuals may present it in a polymorphic status.…”

Genetic Characterization and Sequence Variations in 12S rRNA of Mitochondrial Gene in Three Indian Civets (Viverridae) Species: Implication in Wildlife Forensics

“…Understanding and quantifying the level of sequence divergence across species is crucial in forensics, especially if the species are phylogenetically close [51,52]. The sequence divergence of 12S rRNA for different groups of mammals is mostly between 0.027 and 0.074, except for Proboscidea [53].…”