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Convergence and divergence in sex-chromosome evolution
1Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
Nature Genetics
|February 25, 2017
Summary
The chicken W chromosome assembly reveals conserved gene content across bird species, similar to mammals. Unlike mammalian Y chromosomes, it lacks female-specific genes, indicating divergent sex chromosome evolution.
Area of Science:
- Genomics
- Evolutionary Biology
- Comparative Genomics
Background:
- Sex chromosomes evolve differently in birds and mammals.
- Understanding avian sex chromosome evolution, particularly the W chromosome, is crucial for comparative studies.
Purpose of the Study:
- To reconstruct the gene content of the chicken W chromosome and compare it across 14 bird species.
- To investigate the evolutionary patterns of sex-linked genes in birds and contrast them with mammals.
Main Methods:
- Sequencing and assembly of the chicken W chromosome.
- Comparative analysis of W chromosome gene content across avian species.
- Comparison with mammalian sex chromosome gene content.
Main Results:
- The chicken W chromosome shares similarities with mammalian sex chromosomes in maintaining broadly expressed and dosage-sensitive genes.
- Despite degeneration, the chicken W chromosome is not enriched for genes expressed in female-specific tissues.
- This contrasts with the amplification of testis-specific genes on mammalian Y chromosomes.
Conclusions:
- Inheritance patterns (female-only for W, male-only for Y) influence sex chromosome evolution differently.
- Avian and mammalian sex chromosomes show convergent and divergent evolutionary strategies.
- The study provides insights into the unique evolutionary trajectory of the avian W chromosome.
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