Population Structure, Molecular Systematics, and Forensic Identification of Whales and Dolphins

Validation of a tRNA-Glu-cytochrome b key for the molecular identification of 12 hake species (Merluccius spp.) and Atlantic Cod (Gadus morhua) using PCR-RFLPs, FINS, and BLAST

The goal of this study was to develop a diagnostic key for hake meat to solve the limitations of previous identification methodologies, mainly related to the high degradation of the DNA recovered from processed foods. We describe the development of two molecular tools based on polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphisms of the cytochrome b gene, respectively, to identify DNA from 12 hake species in commercial products. The first assay is an exclusion test consisting of the PCR amplification of a 122 bp fragment using nested primers interspecifically conserved in Merluccius spp. and in Gadus morhua. This 122 bp amplicon, being the shortest one so far designed for hake DNA, is a useful traceability tool for highly degraded samples because its sequence contains enough interspecific diagnostic variation to identify 10 hake species and cod and has been successfully amplified from most commercial products so far tested. The second identification key follows a positive outcome of the exclusion test and consists of the PCR amplification of a 464-465 bp fragment and its digestion with three restriction enzymes whose targets map at interspecifically nonconserved sites of the cytochrome b. The key presented here has passed through a rigorous methodological calibration including its testing for genus specificity, its validation on a large number of authenticated sample types from each species range, and its implementation with a maximum likelihood method for the assignment of unknown samples. Together, these two procedures constitute the most complete molecular key so far developed for Merluccius spp., which is optimal for routine identification of hakes in large commercial samples at a reasonable cost-time ratio.

Applied Evolution

▪ Abstract  Evolutionary biology is widely perceived as a discipline with relevance that lies purely in academia. Until recently, that perception was largely true, except for the often neglected role of evolutionary biology in the improvement of agricultural crops and animals. In the past two decades, however, evolutionary biology has assumed a broad relevance extending far outside its original bounds. Phylogenetics, the study of Darwin's theory of “descent with modification,” is now the foundation of disease tracking and of the identification of species in medical, pharmacological, or conservation settings. It further underlies bioinformatics approaches to the analysis of genomes. Darwin's “evolution by natural selection” is being used in many contexts, from the design of biotechnology protocols to create new drugs and industrial enzymes, to the avoidance of resistant pests and microbes, to the development of new computer technologies. These examples present opportunities for education of the public and for nontraditional career paths in evolutionary biology. They also provide new research material for people trained in classical approaches.