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Sex and neo-sex chromosome evolution in beetles
Ryan Bracewell1,2, Anita Tran1, Kamalakar Chatla1
1Department of Integrative Biology, University of California, Berkeley, California, United States of America.
Plos Genetics
|November 25, 2024
Summary
Beetles exhibit diverse sex determination, with new neo-sex chromosomes evolving from autosomes. This study reveals independent additions to ancestral sex chromosomes, driving karyotype evolution in Coleoptera.
Area of Science:
- Genomics
- Evolutionary Biology
- Entomology
Background:
- Beetles (Coleoptera) represent the most species-rich animal group, displaying significant karyotype diversity.
- Common sex determination mechanisms include XY and X0 systems, with varied evolutionary trajectories.
- Understanding beetle karyotype evolution offers insights into broader chromosomal evolution processes.
Purpose of the Study:
- To reconstruct karyotype evolution across Coleoptera using genomic data.
- To identify conserved ancestral linkage groups (Stevens elements) in beetles.
- To investigate the formation and properties of neo-sex chromosomes in beetles.
Main Methods:
- Whole-chromosome assembly of Tribolium confusum (a species with a neo-sex chromosome).
- Comparative genomic analysis of eleven additional beetle genomes.
- Reconstruction of ancestral linkage groups and sex chromosome evolution.
Main Results:
- Identification of conserved ancestral linkage groups, named Stevens elements, across beetle species.
- Demonstration of independent additions of autosomes to ancestral sex chromosomes, forming neo-sex chromosomes.
- Evidence for the evolution of dosage compensation and non-random gene expression in neo-sex chromosomes.
Conclusions:
- Beetles provide a unique model system for studying sex chromosome evolution due to their diverse karyotypes and neo-sex chromosome formation.
- Independent evolutionary pathways lead to the development of sex chromosome properties, including dosage compensation.
- Comparative genomics of beetle genomes illuminates the dynamic processes shaping karyotype diversity.
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