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Sex-limited experimental evolution drives transcriptomic divergence in a hermaphrodite
Aivars Cīrulis1,2,3, Anna K Nordén1, Allison M Churcher4
1Department of Biology, Lund University, 223 62 Lund, Sweden.
Genome Biology and Evolution
|December 29, 2023
Summary
This study reveals that early evolution of sex chromosomes and distinct sexes involves significant changes in gene expression, particularly in testis-biased genes, during experimental evolution in Macrostomum lignano.
Area of Science:
- Evolutionary biology
- Genomics
- Developmental biology
Background:
- The transition from hermaphroditism to gonochorism involves sex chromosome formation and sex-biased gene expression.
- Sexual selection is hypothesized to drive male-biased gene expression evolution.
- Previous studies relied on theoretical models or ancient sex chromosomes.
Purpose of the Study:
- Investigate gene expression changes during early sex chromosome evolution.
- Examine adaptive gene expression under sex-limited experimental evolution.
- Understand the role of sex-biased gene expression in the evolution of gonochorism.
Main Methods:
- Experimental evolution of the simultaneous hermaphrodite Macrostomum lignano under three selection regimes: female-fitness, male-fitness, and control.
- Characterization of whole-organism gene expression changes after 21-22 generations.
- Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses.
Main Results:
- Female-selected lines exhibited the most substantial changes in gene expression.
- Metabolic alterations, including amino acid biosynthesis and carbon metabolism, were identified as key adaptive components.
- Testis-biased gene candidates showed a tendency towards downregulation in female-selected lines.
Conclusions:
- Changes in testis-biased gene expression are crucial in the early stages of sex chromosome and gonochorism evolution.
- Experimental evolution provides insights into the genetic underpinnings of sexual system transitions.
- Metabolic adaptation plays a significant role in response to sex-limited selection pressures.
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