Double-strand conformation polymorphism (DSCP) analysis of the mitochondrial control region generates highly variable markers for population studies in a social insect

Cytochrome-b variation in Apis mellifera samples and its association with COI-COII patterns

Five Mbo I (Mbo-A, Mbo-M, Mbo-C(1), Mbo-C(2) and Mbo-C(3)) and Hinf I (Hinf-1 to Hinf-5) patterns were observed in Apis mellifera samples after restriction of a 485 bp fragment of the mitochondrial cytochrome-b (cyt-b) gene. Associating the cyt-b Restriction fragment length polymorphism (RFLP) pattern of each sample to its respective previously established COI-COII (Dra I sites) pattern, five restriction patterns (Mbo-C(1), Mbo-C(2), Mbo-C(3), Hinf-1 and Hinf-4) were observed in samples of maternal origin associated to the evolutionary branch C. No deletions or insertions were observed and the nucleotide substitution rate was estimated at 5.4%. Higher nucleotide diversity was observed among the branch C-haplotypes when compared with A and M lineages. Further studies are needed to confirm if the cyt-b + COI-COII haplotypes help to assign certain phylogeographic patterns to the branch C and to clarify phylogenetic relationships among A. mellifera subspecies.

High through-put characterization of insect morphocryptic entities by a non-invasive method using direct-PCR of fecal DNA

The development of non-invasive molecular techniques is currently increasing, particularly in the fields of behavioural ecology and conservation genetics of mammals. Surprisingly, genetic studies of Arthropods and particularly the insects have not benefited yet from the contributions that non-invasive methods have made. Here, we outline a strategy for identifying phytophagous insect genetic entities based on direct-PCR of fecal DNA combined with double strand conformation polymorphism (DSCP) typing. This allows the differentiation of morphocryptic entities within the species Ceutorhynchus assimilis (Coleoptera: Curculionidae), a candidate biocontrol agent of a noxious weed. The results obtained clearly demonstrate the potential for this method to provide a valuable means for genetic and ecological studies of Arthropods.

The utility of the neglected mitochondrial control region for evolutionary studies in lepidoptera (insecta)

The insect mitochondrial control region (=AT-rich-region) is a rarely used genetic marker in phylogeographic studies and population genetic surveys. Reasons for this are that the high AT content and the presence of tandem repeats and indels pose technical and analytical problems. We provide a new pair of primers and the first taxonomically wide-scale description of control region (CR) structure in an insect order after sequencing it in 31 lepidopteran species. We assessed levels of variation occurring in the CR and cytochrome oxidase I (COI) by sequencing and comparison. Intrapopulation analyses in five species of butterflies showed that CR was more variable than COI. Interpopulation variation from three populations of Erebia triaria and E. palarica was slightly lower in the CR than COI with regard to single-nucleotide polymorphisms, but the results were concordant between both markers and highly congruent with regard to population differentiation. Using 15 species of Satyrinae we found that the CR has the same, or stronger, phylogenetic resolution as COI. Our results indicate that the CR can be of importance in addition to COI in population genetic studies. Alignments for the whole CR are direct and unambiguous at the intraspecific level. Indels show phylogenetic signal, but make this marker more complex to use than COI for higher phylogenetic analyses. Nevertheless, alignments at the generic level are straightforward over one part of the CR. The combination CR+COI appears to be a very promising phylogenetic tool to resolve fast-evolving species-level phylogenies.

AFLP-based genetic linkage map of the Colorado potato beetle Leptinotarsa decemlineata: sex chromosomes and a pyrethroid-resistance candidate gene

A genetic linkage map was constructed from an intraspecific cross of the Colorado potato beetle, Leptinotarsa decemlineata. This is an initial step toward mapping the loci that underlie important phenotypes associated with insect adaptation to an agroecosystem. The map was made with 172 AFLP and 10 anonymous codominant markers segregating among 74 backcross (BC(1)) individuals. Markers were mapped to 18 linkage groups and a subset of the markers with a mean intermarker distance of 11.1 cM is presented. A pyrethroid-resistance candidate gene, LdVssc1, was placed onto the map as well. The sex chromosome was identified by exploiting the XO nature of sex determination in this species using patterns of variation at LdVssc1 and the codominant markers.

SSCP is not so difficult: the application and utility of single-stranded conformation polymorphism in evolutionary biology and molecular ecology

All genetic markers are estimators of DNA nucleotide sequence variation. Rather than obtaining DNA sequence data, it is cheaper and faster to use techniques that estimate sequence variation, although this usually results in the loss of some information. SSCP (single-stranded conformation polymorphism) offers a sensitive but inexpensive, rapid, and convenient method for determining which DNA samples in a set differ in sequence, so that only an informative subset need be sequenced. In short, most DNA sequence variation can be detected with relatively little sequencing. SSCP has been widely applied in medical diagnosis, yet few studies have been published in population genetics. The utility and convenience of SSCP is far from fully appreciated by molecular population biologists. We hope to help redress this by illustrating the application of a single simple SSCP protocol to mitochondrial genes, nuclear introns, microsatellites, and anonymous nuclear sequences, in a range of vertebrates and invertebrates.

The current state of insect molecular systematics: a thriving Tower of Babel

Insect molecular systematics has undergone remarkable recent growth. Advances in methods of data generation and analysis have led to the accumulation of large amounts of DNA sequence data from most major insect groups. In addition to reviewing theoretical and methodological advances, we have compiled information on the taxa and regions sequenced from all available phylogenetic studies of insects. It is evident that investigators have not usually coordinated their efforts. The genes and regions that have been sequenced differ substantially among studies and the whole of our efforts is thus little greater than the sum of its parts. The cytochrome oxidase I, 16S, 18S, and elongation factor-1 alpha genes have been widely used and are informative across a broad range of divergences in insects. We advocate their use as standards for insect phylogenetics. Insect molecular systematics has complemented and enhanced the value of morphological and ecological data, making substantial contributions to evolutionary biology in the process. A more coordinated approach focused on gathering homologous sequence data will greatly facilitate such efforts.