Investigation of the dynamics of sex chromosomes and karyotypic evolution in species of the genus Engystomops (Anura, Leptodactylidae)

• Grant number: 25/07690-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2025
• End date: December 31, 2027
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Luciana Bolsoni Lourenço
• Grantee: Jennifer Nunes Pompeo
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 24/00073-2 - Chromosomal variations in two species complexes of Anura: simple polymorphisms or elements with important roles in the speciation process?, AP.R

Abstract

The Edentulus clade of the genus Engystomops is composed of E. pustulosus and the E. freibergi-E. petersi species complex, which includes between five and seven species. Three species within this complex exhibit heteromorphic X and Y sex chromosomes, while two others do not present chromosomal sexual heteromorphism. The sex chromosomes of E. pustulosus, the sister species to the E. freibergi-E. petersi clade, remain unknown. Based on cytogenetic data, including chromosome painting, previous studies have suggested the common origin of the sex chromosomes in E. freibergi, E. petersi, and Engystomops sp. from Amapá/French Guiana, as well as the secondary and independent loss of chromosomal sexual heteromorphism in E. "magnus" and E. "selva". However, the molecular nature of these sex chromosomes and the rearrangements involved in their evolution remain unknown.Additionally, there is a need to expand cytogenetic studies on E. freibergi, a species with a wide geographical distribution in the Amazon. Based on cytogenetic analysis of specimens from Acre, notable karyotypic variation has already been observed in E. freibergi, making it imperative to expand the study areas. In the present study, we aim to advance the understanding of karyotypic evolution in the Edentulus clade, with a particular focus on sex chromosomes. To this end, the genomes of male and female E. freibergi will be sequenced, and a new population of E. freibergi found in Mato Grosso, as well as specimens of E. pustulosus, whose genome has already been sequenced, will be cytogenetically analyzed. Additionally, the repetitive fraction of the E. pustulosus genome will be characterized, and new cytogenetic markers will be obtained to aid in interspecific comparisons.Phylogenetic analyses based on mitochondrial sequences will be conducted to assist in interpreting the cytogenetic data, thereby providing a better understanding of chromosomal evolution within the Edentulus clade of Engystomops. (AU)