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THE SYSTEMATIC APPROACH
Systematic studies form the basis of all scientific work, and this is no coincidence or artificial contrivance. Classifying natural objects is an essential instinct in human beings that enables us to make sense of the world, and the origins of this ability are not hard to trace. For an off-beat and thought-provoking look at this subject see Yoon (2009); as Quentin Wheeler says in a review of that book, taxonomy is the ‘oldest profession practiced by people with their clothes on’, a reference to the belief that Adam was given the task of naming all the creatures (Genesis 2: 19–20).
Superficial characters like colour, shape and even some behaviours are often quickly seen to be of little use in predicting the unknown, which is the value of systematics, even at a domestic level. From careful observations about a few animals or plants we can make generalizations about other species that we have not yet encountered, and this ability to predict the unknown is what makes taxonomy a science rather than simply a technical procedure. Recognizing that plants related to nightshades are likely to be poisonous is clearly valuable, whereas wrongly classifying bats as a kind of bird might entail a long and fruitless wait for them to lay eggs!
Classifying organisms can, of course, be done for different purposes: there is a well-known cartoon by Charles Keene in Punch magazine (1869, vol. 56, p. 96) in which a railway porter is informing a lady of the charge for carrying a tortoise on a train; he tells her that, ‘Cats is “dogs” and rabbits is “dogs” and so’s parrots, but this ’ere “Tortis” is an insect …’.
The terms classification, taxonomy and systematics are often used as if synonymous, but there are some important differences. A classification is basically a way of groupings organisms in a logical way: although it claims to be based on similarities it often ends up emphasizing differences in order to define the boundaries of groups, and no assumptions about processes or underlying causes of any perceived patterns are made. Such systems are often phenetic in nature, based on morphological differences to divide a large taxon into manageable pieces. Systematics uses the principle that similarities are based on shared, derived characters; it therefore assumes an evolutionary, phylogenetic cause, and importantly it makes predictions about the characteristics of groups, whether morphological, behavioural, ecological or physiological. Taxonomy has traditionally been regarded as all about naming things, though it is linked to a classification or a systematic study, because any system of naming has to be based on principles of relationships, whether real or artificial. This narrow definition has led to the perception that taxonomy is a somewhat mechanical process, which simply produces names and groupings on behalf of the real scientists who are carrying out systematic analysis. It is more useful to see taxonomy as the overarching activity of studying phylogenetic relationships, postulating testable hypotheses about distributions of characters, and hence producing useful classifications with meaningful systems of nomenclature that reflect the underlying relationships.
Thus, the need to recognize true relationships between organisms is essential to our perception of the world and to our ability to exist in some kind of harmony with our environment. The importance of taxonomic research is frequently cited, which makes it all the more surprising that support for taxonomy is increasingly hard to find. Even national museums, the custodians of the most important natural history collections in the world, seem to be constantly downgrading the emphasis on taxonomy in their organizational research priorities (Wheeler, 2008), though this is likely to be rooted in the fundamental misunderstanding of the value and true aims of taxonomy, as stated above. This issue is discussed further by Secord (1996).
THE BRITISH INSECTS
The terms ‘British’ and ‘Britain’ are deliberately used rather loosely to include Ireland as part of the British Isles, because many published ‘British’ lists also include Irish species, even if they contain species found in Ireland but not in the UK. However, there are many special Irish lists (see, for example, http://www.habitas.org.uk/invertebrateireland/index.html). With well over a million species of insects known in the world, and many more to be discovered, our fauna of around 24,000 species looks rather insignificant. However, insect diversity is generally much greater in the tropics than in temperate regions (Foottit & Adler, 2009) and the British insect fauna is in the range to be expected at our latitude.
Table 1.1 shows the approximate numbers of species, families and orders of insects known in the world, Europe and the British isles. World figures are based on Foottit and Adler (2009) and Resh and Cardé (2009), European figures are from the Fauna Europaea website, and British figures from the current book. Of course, these numbers can only reflect the species described to date, and are not necessarily indicative of the numbers of species that actually occur. On a world scale, the five largest groups of insects are: (i) Coleoptera; (ii) Lepidoptera...
