Journal of Economic Entomology (2006) 99, 1037-1045

Anthony I. Cognato (2006)
Standard percent DNA sequence difference for insects does not predict species boundaries
Journal of Economic Entomology 99 (4), 1037-1045
Abstract: Diagnosis and assessment of species boundaries of economically important insects are often problematic because of limited morphological and/or biological characters. DNA data can help to identify and revise species. Nonoverlapping intra- and interspecific sequence divergences are often used as evidence for species. Thus, the establishment of a standardized percent nucleotide divergence to predict species boundaries would aid in cases where species status is suspect. However, given variation in nucleotide mutation rates and species concepts, association between a standard percent sequence divergence and species is questionable. This review surveys the percent DNA sequence difference found between sister-species of economically important insects, to assess whether a standard divergence associates with all taxa. Sixty-two comparisons of intra- and interspecific pairwise DNA differences were made for mitochondrial and nuclear loci spanning families of Isoptera, Phthiraptera, Hemiptera, Coleoptera, Lepidoptera, Diptera, and Hymenoptera. Intra- and interspecific sequence divergences varied widely among insects, 0.04-26.0 and 1.0-30.7%, respectively. The ranges of intra- and interspecific sequence divergences overlapped in 28 of 62 comparisons. This implies that a standardized percent sequence divergence would fail to correctly diagnose species for 45% of the cases. Common occurrence of nonmonophyly among closely related species probably explains this observation. Nonmonophyly and overlap of intra- and interspecific divergences were significantly associated. The reviewed studies suggest that a standard percent sequence divergence does not predict species boundaries among economically important insects. DNA data can help best to predict species boundaries via its inclusion in nonphenetic phylogenetic analysis and subsequent systematic expert scrutiny.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Full text of article

Research topic(s) for pests/diseases/weeds:
identification/taxonomy
molecular biology - genes

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Curculio caryae
	Pediculus humanus
	Ips pini
	Archips argyrospila
	Anopheles maculipennis
	Dendroctonus valens
	Ctenopseustis obliquana
	Ips confusus
	Cinara terminalis