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Ultrabithorax function in butterfly wings and the evolution of insect wing patterns
S D Weatherbee1, H F Nijhout, L W Grunert
1Howard Hughes Medical Institute, Laboratory of Molecular Biology, University of Wisconsin, Madison 53706, USA.
Current Biology : CB
|February 18, 1999
Summary
Changes in how the Ultrabithorax (Ubx) gene regulates its targets underlie insect hindwing evolution. This study reveals lineage-specific target gene acquisition by Ubx, driving morphological diversity in homologous structures.
Area of Science:
- Developmental biology
- Evolutionary genetics
- Insect morphology
Background:
- Appendage evolution is crucial for animal diversity, but developmental mechanisms remain unclear.
- Hox genes control homologous appendage development, suggesting regulatory changes drive diversity.
- Limited model organisms and known Hox targets hinder understanding of Hox gene roles in evolution.
Purpose of the Study:
- Investigate the role of Hox genes in morphological evolution.
- Analyze a butterfly mutant (Hindsight) for insights into hindwing pattern transformation.
- Compare target gene regulation by Ultrabithorax (Ubx) in Lepidopteran and Dipteran hindwings.
Main Methods:
- Studied a butterfly homeotic mutant ('Hindsight') with forewing-to-hindwing transformations.
- Examined Ubx gene expression in developing Hindsight hindwings.
- Compared Ubx-mediated gene regulation between butterfly and Drosophila hindwings.
Main Results:
- Loss of Ubx expression in Hindsight mutants correlated with altered wing pigmentation, pattern, and scale morphology.
- Several Ubx-regulated genes in Drosophila halteres were not repressed by Ubx in butterfly hindwings.
- Distal-less (Dll) expression showed unique Ubx regulation in butterflies.
Conclusions:
- Morphological diversification of insect hindwings involves lineage-specific acquisition of Ubx target genes.
- Altered sets of Hox-regulated target genes likely explain the divergence of homologous structures across animal lineages.