The emerging entomologist: the merits of taxonomy

Studying monitor lizards my sample size on morphology was a meagre 6 lizards, of which I collected movement data from 5 individuals. Small numbers achieved from 4 months of hard graft scrambling through dense rainforest for hours every day. Studying ants I have already identified a dizzying 21,085 ants and I am only half way though the arboreal samples I collected from the field not to mention my subterranean samples. Entomology projects cannot be criticised for having low statistical power.

For the last 3 months I have sat at a microscope on a steep and fast learning curve on ant taxonomy. To date I have sorted through 355 samples, counted 21,085 ants and identified them as belonging to 119 different species, 27 genera and 5 subfamilies. A far cry from my days spent searching for only one species of interest the elusive monitor lizard, Varanus bitatawa. Vertebrate and invertebrate studies inevitably differ wildly. Whilst many people are drawn to the charismatic charm cast by many vertebrate species the captivation of many invertebrates is really only revealed under the microscope.

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Ants belong to the family Formicidae and it is estimated that there are over 20,000 ant species of which only around half have been formally classified. The diversity of this family is incredible and is equally reflected in its morphology. From the largest ant in the world, Camponotus gigas, measuring in at just over an inch to some of the smallest ants belonging to the genus Carebara, at only a couple of mm, both extremes can be found in my Bornean samples.  Ants are generally distinguishable from other insects by an elbowed antennae and by a narrow constriction in the abdomen. A feature called the petiole forms a narrow waist joining the upper half of the body (the head and alitrunk) with the lower half (the gaster). Despite sharing common features, the morphological diversity I have observed in my specimens has been astounding. Not only in size but in colour, ranging across a spectrum of oranges and yellows to browns and black, even a metallic blue. Many of the specimens, like Polyrhachis, are armoured with elaborate spines. Assumed to serve as predator deterrence, spines are found ranging in size and number across the alitrunk and petiole. Other genera like Cataulacus resemble military tanks by their distinctive angular heads and bodies with antennae tucked away into grooves on the side of the head. This contrasts sharply with the rounded, elegant heads and long legs of Camponotus. Many of the genera I have encountered have identifiable features to look for, Diacamma are characterized with swirls of fingerprint like marking whilst Crematogaster are distinguishable by their heart shaped gaster. The range in morphology across all specimens display remarkable feats of evolution.

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The process of identification I find is methodical, logical and satisfying. Turning the unknown mixed sample into a beautifully ordered reference collection to be admired and utilised for future projects. Putting ethical questions to one side, the draws of compiling collections and placing order on what appears to be disorder is compelling. Historically collections have been put together by natural historians and by hobbyists from the Victorian age. Scientists have for many years systematically catalogued life on Earth through reference collections and, although far less common now with vertebrates, it is still commonly practised by entomologists.

Measures of biodiversity are reliant on collections of specimens from the field. The ability to easily obtain large samples of insects from varied environments determines that exhaustive hours are required in the laboratory to sort, clean, identify and mount specimens. Recent attendance at the international canopy science conference brought to my attention the growing field of metabarcoding in measurements of biodiversity. This technique first relies on the ability to mass amplify DNA from large collections of mixed specimens using PCR technology. Simply it is to make multiple copies of the same small segment of DNA from the collected organisms, like photocopying the same page of a book again and again.  The genetic code, the order of A, C, G and T bases, of each copied DNA segment is then sequenced using NextGen sequencing techniques. Like reading the letters on each photocopied page and thus being able to determine how many different words exist on the page. The point is that metabarcoding enables the number of different species present in mass collections to be determined without the necessity for the labour exhaustive sorting of samples, a particular problem when working in entomology. It also however removes the need for taxonomic expertise. So is taxonomy a dying skill? As a teacher I was frequently amazed at the ignorance of many of my bright A-Level students when it came to basic natural history. Year on year students were unable to distinguish basic morphological features that differentiated an insect from an arachnid. Yet the same students could tell me about DNA structure, the genetic code and the PCR method. Progressive technology such as metabarcoding should be embraced alongside traditional natural history methods. Data on morphology, behaviour and other life history traits are not obtainable through analysis of the DNA alone. The ability to identify, observe and measure such traits should not be lost in exchange for time and effort saved. The skills of the taxonomist and the natural historian need to be recognized and taught alongside the rapidly developing, and important, world of DNA technology.

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Can I call myself a taxonomist or even a natural historian? Well maybe not quite yet, I have not yet acquired the extensive knowledge to add that label to my CV at this point in time. As an emerging entomologist I have however a new found respect for those that can.

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