Hexapoda: Comparative Aspects of Early Development
Hexapoda not only constitutes the largest taxon in the biological world; its representatives are also the best-studied invertebrates. This chapter will give an overview of general principles of hexapod development, mostly in reference to the detailed desc
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Hexapoda: Comparative Aspects of Early Development Ariel D. Chipman
Chapter vignette artwork by Brigitte Baldrian. © Brigitte Baldrian and Andreas Wanninger. A.D. Chipman The Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Jerusalem, Israel e-mail: [email protected]
A. Wanninger (ed.), Evolutionary Developmental Biology of Invertebrates 5: Ecdysozoa III: Hexapoda DOI 10.1007/978-3-7091-1868-9_2, © Springer-Verlag Wien 2015
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INTRODUCTION Hexapoda not only constitutes the largest taxon in the biological world; its representatives are also the best-studied invertebrates. This chapter will give an overview of general principles of hexapod development, mostly in reference to the detailed description of Drosophila melanogaster (see Chapter 1). The description will be divided along key developmental processes in early development, leading from oogenesis through early patterning and ending in segmentation. Later development is covered in Chapter 3. Detailed morphological descriptions of embryonic development exist for many more species than do molecular descriptions of development. This chapter will focus on species for which some of the molecular basis of development is known, with some general morphological details on other species. Morphological descriptions, mostly from the early to mid-twentieth century, are reviewed thoroughly in the book edited by Counce and Waddington (1972).
Fig. 2.1 A phylogeny of the hexapod orders mentioned in the text, with the main model organisms listed for each order. The three insect groups are marked above. Note that
A.D. Chipman
Hexapoda is traditionally divided into three groups: the paraphyletic “Ametabola” and “Hemimetabola” and the monophyletic Holometabola (Fig. 2.1). In the following, a brief introduction to each group and the main model species in that group is given. The “Ametabola” is also referred to as “Apterygota” and includes the wingless insects and the non-insect hexapods. They typically go through an indeterminate number of molts, including adult molts. This is a relatively small group and includes several main basal lineages: Thysanura/Zygentoma (silverfish, firebrats, and relatives), Protura (coneheads), Diplura (bristletails), and Collembola (springtails). Strictly speaking, of these hexapod taxa, only Thysanura are contained within the Insecta. Relatively little is known about their development, and there are as yet almost no good model species. For the non-insect groups, there have been some attempts to use the springtail Folsomia candida as a model species, but this has proved largely unsuccessful. Recently, the springtail Orchesella cincta has emerged as an experimentally amenable species,
only Holometabola is a true monophyletic clade. Data assembled from multiple sources
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Hexapoda: Comparative Aspects of Early Development
but to date the only published studies have to do with Hox gene control of appendage patterning (Konopova and Akam 2014). The firebrat Thermobia domestica can be kept in the lab
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