Amplified fragment length polymorphism analysis supports the valid separate species status of Lucilia caesar and L. illustris (Diptera: Calliphoridae)

Christine J Picard,Jeffrey D Wells,Anne Ullyot,Knut Rognes

doi:10.1080/20961790.2017.1398286

Abstract

ABSTRACTCommon 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.

Highlights

Flies within the forensically and medically important genus Lucilia Robineau-Desvoidy provide several examples of mitochondrial DNA paraphyly [1]
In the most extensively studied example of L. cuprina and L. sericata, shared haplotypes may have resulted from mitochondrial DNA (mtDNA) introgression because of hybridization [4]
Other Lucilia species have been investigated less than L. sericata/cuprina, but Sonet et al [12] found that L. caesar/illustris shared both mtDNA and nuclear ribosomal genotypes, leading those authors to question the insects’ status as separate species

Summary

Introduction

Flies within the forensically and medically important genus Lucilia Robineau-Desvoidy provide several examples of mitochondrial DNA (mtDNA) paraphyly [1]. This presents a problem for identifying larval specimens during investigation of a suspicious death or myiasis [2], some of these problems may be overcome with detailed species distribution knowledge [3]. In the most extensively studied example of L. cuprina and L. sericata, shared haplotypes may have resulted from mtDNA introgression because of hybridization [4]. Whilst morphological analysis indicates these species are closely related [14], they are morphologically distinct and display different environmental preferences [15]

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Results

Conclusion