Sex chromosomes evolution in Characoidei fishes

• Grant number: 24/03891-8
• Support Opportunities: Research Projects - Thematic Grants
• Start date: January 01, 2025
• End date: December 31, 2029
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Agreement: ANR
• Principal Investigator: Fausto Foresti
• Grantee: Fausto Foresti
• Principal researcher abroad: Guiguen Yann
• Institution abroad: Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Paris, France
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated researchers: Alessandro de Mello Varani ; Claudio de Oliveira ; Diogo Teruo Hashimoto ; Fábio Fernandes Roxo ; Fábio Porto-Foresti ; Ricardo Utsunomia

Abstract

Sex chromosomes (SC) evolution is a long-standing question in evolutionary biology. H.J. Muller's century-old theory suggests that SC evolve by fixing a new sex-determining gene (SD) on an ancestral autosome. Over time, sex-specific alleles accumulate, leading to recombination loss and ultimately SC degeneration. While this unidirectional scenario aligns with SC evolution in well-studied models with highly differentiated SC like mammals, birds, and Drosophila, recent insights challenge it, like in teleost fishes, where rapid SC and SD turnovers are observed along with a wide range of SC differentiation. To challenge this theory, we will explore SC evolution on a large macro-evolutionary scale (100 species) using high-resolution genomics (de novo genome assemblies, population genetics, genome editing) and advanced cytogenetics (Oligopaint FISH) in the Characoidei clade, a 100-million-year-old, species-rich vertebrate group. Species in this clade exhibit diverse SC systems i.e., monofactorial systems, multiple SC and even sex-linked supernumerary B chromosomes, highlighting a complex array of SC turnovers. Their SC differentiation is very dynamic, from cytologically undifferentiated to highly differentiated SC, even sometime within closely related species or populations. This clade also includes major aquaculture species in which tools for precise sex control will be highly relevant, and many small aquarium trade species suitable for laboratory experimentation. Our genomics and cytogenetics-based SC characterizations will allow to infer the number and age of SC/SD turnovers and the precise comparison of non-recombining region size and organization among conserved homologous SC. This project will capitalize on French and Brazilian partners complementary expertise, particularly in genomics and cytogenetics and will also leverage resources from Neotropical species in both French Guiana and Brazil, ensuring a comprehensive study of SC evolution in the Characoidei clade. (AU)