title: Blastoderm segmentation in Oncopeltus fasciatus and the evolution of insect segmentation mechanisms.
abstract: Segments are formed simultaneously in the blastoderm of the fly Drosophila melanogaster through a hierarchical cascade of interacting transcription factors. Conversely, in many insects and in all non-insect arthropods most segments are formed sequentially from the posterior. We have looked at segmentation in the milkweed bug Oncopeltus fasciatus. Posterior segments are formed sequentially, through what is probably the ancestral arthropod mechanism. Formation of anterior segments bears many similarities to the Drosophila segmentation mode. These segments appear nearly simultaneously in the blastoderm, via a segmentation cascade that involves orthologues of Drosophila gap genes working through a functionally similar mechanism. We suggest that simultaneous blastoderm segmentation evolved at or close to the origin of holometabolous insects, and formed the basis for the evolution of the segmentation mode seen in Drosophila We discuss the changes in segmentation mechanisms throughout insect evolution, and suggest that the appearance of simultaneous segmentation as a novel feature of holometabolous insects may have contributed to the phenomenal success of this group.
authors.affiliation: The Department of Ecology, Evolution and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram 91904, Jerusalem, Israel.
authors.forename: Reut
authors.initials: R
authors.lastname: Stahi
authors.affiliation: The Department of Ecology, Evolution and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram 91904, Jerusalem, Israel ariel.chipman@huji.ac.il.
authors.forename: Ariel D
authors.identifier: 0000-0001-6696-840X
authors.initials: AD
authors.lastname: Chipman
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001756:Blastoderm / Q000196:embryology*; D019521:Body Patterning; D004331:Drosophila melanogaster; D018507:Gene Expression Regulation, Developmental; D020062:Heteroptera / Q000196:embryology* / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: D019476:Insect Proteins; D014157:Transcription Factors
keywords: blastoderm; evo-devo; insects; segmentation; transcription factors