Chapter

96 features are said to show homoplasy (analogy) and are the result of either parallelism (the features had a distant, common ancestor) or convergence (the features are derived from entirely unrelated ancestral conditions). Once homology is established, it is then a matter of determining whether the character states under consideration are advanced (derived) or primitive (ancestral) (apomorphies or plesiomorphies, respectively). Both comparative morphology of extant forms and the fossil record have been used extensively in such determinations. Apomorphies shared by taxa are said to be synapomorphies, while those unique to ataxon are described as autapomorphies. Neither autapomorphies nor plesiomorphies can show relationships between groups. Broadly speaking, the greater the number of synapo-morphies, the closer will be the relationship between taxa. Each taxon, regardless of rank, will have a sister group—its closest relative—so that the development of classifications and phylogenies is the establishment of successively larger sister groups, often depicted as a branching diagram known as a phylogenetic tree (see the section on Phylogeny and Classification under each order for examples). An ancestor and all of its descendants form a monophyletic group; when some of the descendants are lacking, the remaining descendants are said to be paraphyletic. Groups derived from more than one ancestor are said to be polyphyletic. It must be emphasized that the actual ancestor of two taxa is rarely known, though its general features (the so-called "ground plan") will be defined by the plesiomor-phic characters of its descendants. The term stem group refers to collections of fossils that have some plesiomorphic characters of a more recent group; they may be close to, but are not directly on, the group's line of descent.

As the following section (and comparison of the current with previous editions of this book) shows, ideas on relationships among insect groups change with time, sometimes quite significantly. Though partly related to the acquisition of new knowledge, it is also because taxonomists differ in their analysis and interpretation of data, or use different data sets on which to base their conclusions.

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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