Phylogeny and Classification

From a structural comparison of primitive living Mecoptera and Diptera and from the relatively scarce fossil evidence, it seems probable that Diptera evolved from mecopteralike insects in the Permian period. Permotipula patricia, from the Upper Permian of Australia, was originally thought to be the oldest dipteran. However, it is now considered an early Mecopteran. Similarly, other four-winged forms (the Protodiptera Permotanytarsus and Choristotanyderus) from the same strata, which were originally considered to be Diptera (Riek, 1977), have been reexamined and, as a result, moved from the dipteran stem group (Willmann, 1989; Wootton and Ennos, 1989). Thus, the earliest reliable records of fossil Diptera come from the Middle Triassic, though these are quite meager. By the late Triassic, the more primitive suborder, Nematocera, had undergone a considerable radiation, possibly making use of the honeydew produced by the already abundant homopterans (Downes and Dahlem, 1987). By the Lower Jurassic, well-developed Nematocera (some assignable to recent families) and primitive orthorrhaphous forms were present. The Mus-comorpha (Cyclorrhapha) evolved from orthorrhaphan stock, probably in the Late Jurassic. The great radiation of the order, and the establishment of many of the structures and habits of modern flies, took place in the Cretaceous period. This was, of course, correlated with the evolution of the flowering plants and mammals. By the Eocene period, the dipteran fauna was similar in many respects to that which survives today. Indeed, many Eocene fossils are assigned to modern genera. A possible phylogeny of the order is shown in Figure 9.3.

Classification of the modern Diptera continues to present problems, particularly the rank assignable to different groups. The difficulty arises in part because the order is extremely old; it contains many extinct groups and others that are in decline; and yet there are also groups that are still evolving at a rapid rate. Thus, while ancient families have well-established differences and are easily separated, more recent groups, notably the families and superfamilies of Muscomorpha, are sometimes little more than convenient divisions because of the vast number of species that must be considered. The differences between these groups, therefore, are relatively minor. The classification used here is adapted from the views presented in the Manual ofNearctic Diptera (McAlpine et al., 1981-1989). In this arrangement, the Diptera are arranged in two suborders, Nematocera and Brachycera. Within the Nematocera, seven infraorders are recognized. Figure 9.3 indicates that Nema-tocera are monophyletic. However, it should be noted that some authors believe that this is a paraphyletic group, with the Bibionomorpha or Psychodomorpha being the sister group to the Brachycera (Yeates and Wiegmann, 1999). In the undoubtedly monophyletic Brachycera there are three infraorders; the first two, Asilomorpha and Tabanomorpha, correspond to the "Orthorrhapha" while the third, Muscomorpha, is equivalent to the "Cyclorrhapha" of

FIGURE 9.3. A suggested phylogeny of the Diptera. [After J. F. McAlpine and D. M. Wood, coordinators, 1989, Manual ofNearctic Diptera, Vol. 3, Agriculture Canada Monograph No. 32. By permission of the Minister of Supply and Services Canada.]

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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