A role for barcoding in the study of African fish diversity and conservation

Introduction Biodiversity assessments and implementation of conservation actions worldwide are hampered by slow progress in taxonomic research, termed the Taxonomic Impediment. The existing workforce of taxonomists cannot cope with the overwhelming need for basic field surveys, species descriptions and systematic revisions to provide basic information for conservation planning. In addition, Costa and Carvalho suggested that few taxonomists are able to distinguish critically between more than 1000 taxa. The reality facing taxonomy is that there may be more species that remain to be discovered on Earth than those that have already been described. It is estimated that 1.4–1.8 million species have been described out of a possible total of approximately 7–15 million. Species and populations are going extinct at an alarming but poorly understood rate. Many species may be going extinct before they can be identified or described. This presents a problem for conservation planning and prioritization, obviously because species that have not been identified cannot be protected effectively. This problem is especially evident in Africa, whose rich biodiversity is poorly known. Taxonomic expertise is lacking even for major and commercially important groups. The few taxonomists who are working in developing countries, home to more than 95% of globally described species, find it difficult to access basic taxonomic information such as species descriptions. Where taxonomic keys are available, they are rarely revised and often inadequate to identify specimens unambiguously to the species level. A further problem in Africa is that funding for taxonomic research and the museums or facilities that host biodiversity collections has been poor or non-existent, few new taxonomists are being trained, retirees are often not replaced and salaries are not competitive, such that the overall taxonomic expertise is declining. There have been strident calls on the taxonomy community to embrace new technologies and to form networks to speed up the description of biodiversity and to improve our ability to identify species. How this could be achieved without compromising rigorous taxonomic research principles is, however, questioned. There is legitimate concern that too little money is being spent on morphological taxonomy compared to molecular studies. A purely DNA taxonomy approach (e.g. Blaxter), not to be confused with DNA barcoding, is too simplistic in our view. DNA taxonomy can, however, provide additional characters for discrimination, especially in cases where other characters vary among species and are thus difficult to interpret. Therefore we do not agree with de Carvalho et al. that a molecular approach will do little to address the real problems in taxonomy. In our experience, most traditional taxonomists welcome the opportunity to refer to molecular data, but DNA taxonomy should not replace taxonomic research that can be based on multiple character data sets. Nucleotide sequence divergence in short, standardized gene regions (DNA barcodes) can be used to identify known species and facilitate the discovery of new ones. Mitochondrial DNA is a valuable marker in population genetic or phylogeographic studies because it is maternally inherited, evolves rapidly and recombination is rare or absent. Therefore, a part of the mitochondrial cytochrome oxidase subunit I (COI) has been chosen as a standard gene region for barcoding animals. Although there was no a priori reason for choosing COI among the 13 protein-coding mitochondrial genes, it has the advantage of having robust universal primers that can recover the 5’ end of COI of most animal species. Barcoding of species has become cheaper through the technological advances made by other molecular programmes, especially the human genome project. Rapid barcoding and comparison with the growing database of COI sequences will increase the speed of identification of newly collected or unknown specimens. This may focus taxonomists’ attention on unidentified lineages, and with the addition of morphological and other taxonomically relevant data, could lead to a faster rate of species description. The Consortium for the Barcode of Life (CBOL) was established as a growing coalition of biodiversity organizations interested in developing barcoding as a global standard for DNA-based species identification. CBOL promotes FISH-BOL as an international campaign to barcode all marine and freshwater fish. FISH-BOL consists of ten regional working groups representing Africa, Australia, Oceania/Antarctica, the Americas (North, Central and South America), Europe and Asia (India, North East Asia, and South East Asia). Each of these regional working groups is charged with the task of organizing support and participation to barcode the ichthyofauna within their region, based on expert-identified voucher specimens. The main purpose of barcoding is to identify species reliably, Review Articles South African Journal of Science 104, July/August 2008 293