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Sex Chromosome Turnovers and Stability in Snakes
Tomáš Pšenička1, Barbora Augstenová1, Daniel Frynta2
1Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic.
Molecular Biology and Evolution
|December 13, 2024
Summary
Snake sex chromosome evolution is complex, with multiple origins of ZZ/ZW and XX/XY systems. Recent studies reveal diverse sex chromosome systems across snake lineages, challenging previous assumptions.
Area of Science:
- * Evolutionary genetics
- * Comparative genomics
- * Herpetology
Background:
- * Snakes were long considered a model for gradual ZZ/ZW sex chromosome differentiation.
- * Recent findings indicate ZZ/ZW systems are limited to caenophidian snakes.
- * Non-caenophidian boas and pythons exhibit nonhomologous XX/XY sex chromosomes.
Purpose of the Study:
- * To identify sex chromosomes in non-caenophidian snake species.
- * To investigate sex chromosome homology across diverse snake lineages.
- * To elucidate the complex evolutionary history of snake sex chromosomes.
Main Methods:
- * Genome coverage analysis in four non-caenophidian species.
- * Comparative analysis of sex chromosome homology across phylogenetic lineages.
Main Results:
- * Sex chromosomes were identified for the first time in 13 non-caenophidian species.
- * Snake sex chromosome evolution involves multiple transitions to both XX/XY and ZZ/ZW systems.
- * Genomic regions were repeatedly co-opted as sex chromosomes, even with opposite heterogamety.
- * Rates of sex chromosome differentiation vary significantly among snake lineages.
- * Snakes likely had ancestral sex chromosomes prone to turnover, stabilizing later in caenophidians.
Conclusions:
- * Snake sex chromosome evolution is more complex than previously understood.
- * Multiple independent origins and turnovers of sex chromosomes occurred across snake phylogeny.
- * Snakes offer a valuable model for studying sex chromosome evolution dynamics.
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