Genitalia play an important role in the life histories of insects, as in other animals. These sexually dimorphic structures evolve rapidly and derive from multiple body segments. Despite the importance of insect genitalia, descriptions of their genetic patterning have been limited to fruit flies. In this study, we report the functions, interactions and regulation of appendage patterning genes (e.g. homothorax, dachshund, and Distal-less) in two insects: the milkweed bug Oncopeltus fasciatus, and the red flour beetle Tribolium castaneum. These species differ in the anatomical complexity of their genitalia. Females of T. castaneum have a terminal ovipositor ending in short styli, while O. fasciatus have a multi-jointed subterminal ovipositor. Male O. fasciatus have a genital capsule consisting of large gonocoxopodites and claspers; T. castaneum males have relatively simple genitalia. The requirement of appendage-patterning genes in males differed between the two species: No defects were observed in T. castaneum male genitalia, and while the male claspers of O. fasciatus were affected by depletion of appendage-patterning genes, the proximal gonocoxopodite was not, suggesting a non-appendicular origin for this structure. Only the styli of the T. castaneum ovipositor were affected by RNAi depletion of appendage-patterning genes (14 genes in all). The posterior Hox genes (abdominal-A and Abdominal-B) were required for proper genital development in O. fasciatus and regulated Distal-less and homothorax similarly in both sexes. Distal-less and dachshund were regulated differently in male and female O. fasciatus. Knockdown of the sex determination gene intersex produced a partial female-to-male transformation of abdominal and genital anatomy and also resulted in abrogation of female-specific regulation of these genes. These results provide developmental genetic support for specific anatomical hypotheses of serial homology. Importantly, these gene functions and interactions describe the developmental patterning of sexually dimorphic structures that have been critical to the diversification of these species-rich insect groups.
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http://dx.doi.org/10.1016/j.ydbio.2011.09.026 | DOI Listing |
Curr Opin Insect Sci
June 2024
Misaki Marine Biological Station, The University of Tokyo, Miura, Kanagawa 238-0225, Japan. Electronic address:
PeerJ
September 2023
University Instrumentation Center, University of New Hampshire, Durham, New Hampshire, United States.
In the literature there are numerous reports of developmental deformities in arthropods collected in their natural habitat. Since such teratogenically affected individuals are found purely by chance, the causes of their defects are unknown. Numerous potential physical, mechanical, chemical, and biological teratogens have been considered and tested in the laboratory.
View Article and Find Full Text PDFBMC Biol
May 2023
Department of Ecology & Evolution, University of Chicago, Chicago, IL, 60637, USA.
Background: Highly diverse butterfly wing patterns have emerged as a powerful system for understanding the genetic basis of phenotypic variation. While the genetic basis of this pattern variation is being clarified, the precise developmental pathways linking genotype to phenotype are not well understood. The gene aristaless, which plays a role in appendage patterning and extension, has been duplicated in Lepidoptera.
View Article and Find Full Text PDFProc Biol Sci
June 2022
Department of Biology, Duke University, Durham, NC 27708, USA.
Treehoppers of the insect family Membracidae have evolved enlarged and elaborate pronotal structures, which is hypothesized to involve co-opted expression of genes that are shared with the wings. Here, we investigate the similarity between the pronotum and wings in relation to growth. Our study reveals that the ontogenetic allometry of the pronotum is similar to that of wings in Membracidae, but not the outgroup.
View Article and Find Full Text PDFCell
February 2021
Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Orthopedic Research, Boston Children's Hospital, Boston, MA 02115, USA. Electronic address:
Changes in appendage structure underlie key transitions in vertebrate evolution. Addition of skeletal elements along the proximal-distal axis facilitated critical transformations, including the fin-to-limb transition that permitted generation of diverse modes of locomotion. Here, we identify zebrafish mutants that form supernumerary long bones in their pectoral fins.
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