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This content will become publicly available on March 1, 2026

Title: A Conserved Somatic Sex Determination Cascade Instructs Trait‐Specific Sexual Dimorphism in Horned Dung Beetles
ABSTRACT Sex‐specific trait expression represents a striking dimension of morphological variation within and across species. The mechanisms instructing sex‐specific organ development have been well studied in a small number of insect model systems, suggesting striking conservation in some parts of the somatic sex determination pathway while hinting at possible evolutionary lability in others. However, further resolution of this phenomenon necessitates additional taxon sampling, particularly in groups in which sexual dimorphisms have undergone significant elaboration and diversification. Here, we functionally investigate the somatic sex determination pathway in the gazelle dung beetleDigitonthophagus gazella, an emerging model system in the study of the development and evolution of sexual dimorphisms. We find that RNA interference (RNAi) targetingtransformer (tra)caused chromosomal females to develop morphological traits largely indistinguishable from those normally only observed in males, and thattraRNAiis sufficient to induce splicing of the normally male‐specific isoform ofdoublesexin chromosomal females, while leaving males unaffected. Further,intersexRNAiwas found to phenocopy previously described RNAi phenotypes ofdoublesexin female but not male beetles. These findings match predictions derived from models of the sex determination cascade as developed largely through studies inDrosophila melanogaster. In contrast, efforts to targettransformer2via RNAi resulted in high juvenile mortality but did not appear to affectdoublesexsplicing, whereas RNAi targetingSex‐lethaland two putative orthologs ofhermaphroditeyielded no obvious phenotypic modifications in either males or females, raising the possibility that the function of a subset of sex determination genes may be derived in select Diptera and thus nonrepresentative of their roles in other holometabolous orders. Our results help illuminate how the differential evolutionary lability of the somatic sex determination pathway has contributed to the extraordinary morphological diversification of sex‐specific trait expression found in nature.  more » « less
Award ID(s):
2243725
PAR ID:
10608600
Author(s) / Creator(s):
; ;
Publisher / Repository:
Evolution & Development
Date Published:
Journal Name:
Evolution & Development
Volume:
27
Issue:
1
ISSN:
1520-541X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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