High-tech DNA techniques such as polymerase chain reaction (PCR), DNA sequencing, and micro-arrays have revolutionized all aspects of biology. My genetics professor as an undergrad, a traditional bristle-counting fruit fly geneticist, predicted that molecular genetic techniques would spark are theoretical and technical revolution in biology akin to the paradigm shift that quantum mechanics caused in physics. Medicine, ecology, taxonomy; they will never be the same.
Genetic barcoding will undoubtedly change taxonomy and systematics dramatically. Developing diagnostic barcodes for different taxa will allow much higher resolution and much faster speed in characterizing new species. New organisms will be able to be identified simply by “dredging” soil, water, and other substrates. A sample of any material could then be screened using barcoding techniques and any new species would emerge through the magic of PCR. Taxonomy is often marginalized as an esoteric activity best suited for Victorian parlours and musty beetle collectors. Our most important biologists, from Darwin and Wallace to E.O. Wilson, have all been detail-orientated taxonomists. Barcoding will likely bring taxonomy into greater significance in the study of all fields of biology, from human diseases to biodiversity.
While barcoding in the lab will help identify millions of new microorganisms and resolve the phylogeny of thousands of other taxa, a large portion of taxonomy will remain down and dirty. Field-based taxonomy requires more than just deft laboratory skills, but a keen eye, years of experience, and naturalists spirit of adventure. It this type of taxonomy – in the jungle, under the sun – that will remain most important for defining ecological interactions and developing conservation plans to conserve the world’s severely threatened biodiversity.
E.O Wilson estimates that the number of species on the earth varies between 3.5 to over 110 million most of which have not been discovered. Wilson is the world’s leading proponent of routing out as many species as possible, most of which are bacteria, fungi, and other microorganisms. It is invertebrates and vertebrates, from monarch butterflies to orangutans, that are of the most imperiled by deforestation and climate change. The number of these organisms are not insignificant: the International Union for the Conservation of Nature (ICUN) has tallied close to 1.2 million invertebrates and at least 60,000 vertebrates. Almost 9,000 of these are considered threatened. That habitat of many is being threatened by deforestation and other changes in the landscape. Climate change will likely effect all species to some degree, putting many in danger of extinction.
Many of these invertebrate and vertebrate species differ from each other, however, in very subtle ways. For example, my undergraduate advisor defined new mite species by counting variation in the number of bristles on their body. Also, marsh wrens in North America are considered one species but have been separated into two distinct groups, eastern and western. There are 14 subspecies among these two geographic grouping. A key basis for the east-west divide has been demonstrated by ornithologist Donald Kroodsma to be their song. Thus, fine-scale variation between species such microscopic hairs and modulation in bird songs can define new species, important subspecies, or other levels of variation and diversity important to conserve. The most informed conservation plans will require understanding these levels of diversity among and within species.
Despite their power, the DNA techniques of genetic barcoding will not be able to detect the subtle variations that often delineate very similar species, subspecies, and populations from each other. If mega flora and fauna like orangutans and snow leopards are the juicy meat of biodiversity, small scale variations are the potatoes. Fine-scale variations account for a phenomenal amount of biodiversity – if there are 110 million species, how many subspecies? How many geographically or genetically distinct populations?
These small scale variations are also the front lines of evolution. Sub-speciation can be one of the first steps towards development of a new species. Two species that appear the same but have subtle behavioral or morphological difference have taken another stride towards divergence along different evolutionary paths
In order to determine these different species, subspecies, and population it takes a dedicated and skilled taxonomist in the field sampling. It is this type of taxonomist, with their expert eye, experience, and dirt under their finger nails that will provide the information for ecologists and conservation biologists. Barcoding will be a revolutionary technique, but it will not replace or make redundant the fundamental field-based taxonomic techniques of biology.