From repeats to chromosomes: integrating the repeatome with karyotype and sex chromosome evolution in Erythrinidae fishes (Characiformes, Teleostei).

• Grant number: 26/05486-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2026
• End date: March 31, 2027
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Marcelo de Bello Cioffi
• Grantee: Leticia Cristina de Souza
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 24/12644-4 - Connecting genome sequences to chromosomes: bridging the gap between genomic and cytogenetic data, AP.TEM

Abstract

The huge karyotypic diversity of Erythrinidae (Characiformes, Teleostei) makes it an excellent model for investigating chromosomal evolution. Extensive genomic structural variation can be observed for species complexes like Hoplias malabaricus and Erythrinus erythrinus, which possess several karyomorphs, variable diploid numbers, and unique sex chromosome systems. The genomic mechanisms underlying such chromosomal diversification are still poorly understood, despite the fact that the cytogenetic traits of these species have been thoroughly recorded. This project seeks to investigate the association between repetitive DNA sequences and chromosomal rearrangements in H. malabaricus (Kar B- XY system) and E. erythrinus (Kar D- X1X2Y system, integrating genomic and cytogenetic approaches to shed light on the processes driving their evolution. Low-coverage genome sequencing will be used to describe their repetitive DNA landscapes (repeatomes). To establish their chromosomal location, selected satellite DNA families will be PCR-amplified and used as probes in fluorescence in situ hybridization (FISH) assays. By integrating comparative repeatome analyses with in silico and cytogenetic mapping, we aim to resolve the spatial genomic architecture underlying repeat dynamics and their relationship with chromosomal structure. This approach will help clarify how repetitive DNA contributes to sex chromosome evolution and the broader processes driving karyotype diversification. (AU)