Sex chromosome turnovers and genetic drift: a simulation study

Area of Science:

• Evolutionary genetics
• Genomics
• Population genetics

Background:

• Genomic technologies reveal frequent sex chromosome turnover in diverse species.
• Evolutionary drivers of sex chromosome turnover are not well understood.
• Genetic drift's role in turnover is increasingly considered.

Purpose of the Study:

• To analyze sex chromosome turnover dynamics using simulations.
• To investigate the influence of genetic drift on turnover rates.
• To examine how system type and dominance affect turnover likelihood.

Main Methods:

• Individual-based simulations were employed.
• Analysis focused on different sex chromosome systems (XY, ZW).
• Epistatic dominance of sex-determining factors was modeled.

Main Results:

• Drift-mediated turnovers are generally easier than neutral marker substitutions.
• Turnover likelihood depends on sex chromosome system and dominance.
• Drift-mediated turnovers preserving heterogamety are 2-4x more likely than those changing it.
• This ratio decreases with effective population size and can reverse in polygynous systems.

Conclusions:

• Genetic drift plays a significant role in sex chromosome turnover.
• Turnover dynamics are influenced by system type and dominance interactions.
• Drift-mediated selection can favor turnovers that maintain the heterogametic sex.