Evolution of multiple sex chromosomes in Leptidea butterflies
In a comprehensive study published in Heredity, we deciphered the origin and evolution of unique system of multiple sex chromosomes in three cryptic species of Leptidea wood white butterflies.
Image description: Upper left panel: BAC-FISH analysis and schematic drawing of the sex-chromosome multivalent in female pachytene of Leptidea juvernica. BAC clones mapping to different Z chromosomes are marked with a different colour. Chromosomes were stained with DAPI (grey). Bar = 10 μm. Lower left panel: schematic illustration of multiple sex-chromosomes in Leptidea juvernica female. Right panel: mating of Leptidea sinapis (Ibiza, Balearic Islands - photo Roger Vila).
Multiple sex chromosomes formed by rearrangements with autosomes are rare in female heterogametic taxa (WZ/ZZ), hampering studies on their evolutionary drivers and significance. Three cryptic species of Leptidea wood white butterflies – L. juvernica, L. sinapis and L. reali – have unique and exceptionally complex multiple sex chromosomes with 3–4 W chromosomes and 3–4 Z chromosomes. In this study, we provide evidence of evolutionary mechanisms resulting in the chain of events that led to the formation of their species-specific sex chromosome systems. We also demonstrate, for the first time in species with female heterogamety, gradual molecular degeneration of originally autosomal parts translocated onto W chromosomes that represent evolutionary strata of various age and levels of differentiation. These findings are important for understanding general mechanisms of the evolution of multiple sex chromosomes and their role in population divergence and speciation.
Yoshido A., Šíchová J., Pospíšilová K., Nguyen P., Šafář J., Provazník J., Voleníková A., Vila R., Marec F. (2020) Evolution of multiple sex-chromosomes associated with dynamic genome reshuffling in Leptidea wood-white butterflies. Heredity. Published online: 9 June 2020. DOI: 10.1038/s41437-020-0325-9