Taxonomy and classification

Current classifications of insects are based on a combination of ideas for how to recognize the rank and relationships of groups, with most orders being based on groups (taxa) with distinctive morphology. It does not follow that these groups are monophyletic; for instance, the traditionally defined Blattodea and Psocoptera were each paraphyletic (see below in the discussion of each order in section 7.4.2). However, it is unlikely that any higher-level groups are polyphyletic. In many cases, the present groupings coincide with the earliest colloquial observations on insects, for example the term "beetles" for Coleoptera. However, in other cases, such old colloquial names cover disparate modern groupings, as with the old term "flies", now seen to encompass unrelated orders from mayflies (Ephemeroptera) to true flies (Diptera). Refinements continue as classification is found to be out of step with our developing understanding of the evolution of the Hexapoda. Thus, current classifications increasingly combine traditional views with more recent ideas on phylogeny.

Difficulties with attaining a comprehensive, coherent classification of the insects (at all taxonomic levels; see Table 1.1 for the taxonomic categories) arise when phylogeny is obscured by complex evolutionary diversifications. These include radiations associated with adoption of specialized plant or animal feeding (phytophagy and parasitism; section 8.6) and radiations from a single founder on isolated islands (section 8.7). Sometimes the evolution of reproductive isolation of closely related taxa is not accompanied by obvious (to humans) morphological differences among the entities, and it is a challenge to delimit species. Difficulties may arise also because of conflicting evidence from immature and adult insects, but, above all, problems derive from the immense number of species (section 1.3.2).

Scientists who study the taxonomy of insects - i.e. describe, name, and classify them - face a daunting task. Virtually all the world's vertebrates are described, their past and present distributions verified, and their behaviors and ecologies studied at some level. In contrast, perhaps only 5-20% of the estimated number of insect species have been described formally, let alone studied biologically. The disproportionate allocation of taxonomic resources is exemplified by Q.D. Wheeler's report for the USA of seven described mammal species per mammal taxonomist in contrast to 425 described insects per insect taxonomist. These ratios, which probably have worldwide application, become even more alarming if we include estimates of undescribed species. There are very few unnamed mammals, but estimates of global insect diversity may involve millions of unde-scribed species.

New species and other taxa of insects (and other organisms) are named according to a set of rules developed by international agreement and revised as practices and technologies change. For all animals, the International Code of Zoological Nomenclature regulates names in the species, genus, and family groups (i.e. from infraspecific to superfamily level). The standard use of a unique binomen (two names) for each species (section 1.4) ensures that people everywhere can communicate clearly. Unique and universal names for taxa result from making new names available through permanent publication with the appropriate designation of type specimens (that serve as the reference for names), and by recognizing the priority of names (i.e. the oldest available name is the valid name of a taxon). Today much controversy is centered upon what constitutes a "published" work for the purposes of nomenclature, principally due to the difficulty of ensuring permanence and long-term accessibility of electronic publications.

When a new insect species is recognized and a new name published, it must be accompanied by a published description of the appropriate life stages (almost always including the adult) in sufficient detail that the species can be distinguished from its close relatives. Features diagnostic of the new species must be explained and any variations in appearance or habits described or discussed. Sometimes diagnostic nucleotide sequences will be available for one or more genes of the new species and these can be deposited in online databases, such as GenBank. Indeed, comparison of sequences from a number of related specimens and populations often lead to the recognition of new species that were previously "cryptic" due to similar morphology. Species delimitation remains one of the challenging tasks of taxonomy and new character systems are being explored in many insect groups (Box 7.1).

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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