Chromosomal variations in two species complexes of Anura: simple polymorphisms or elements with important roles in the speciation process?

• Grant number: 24/00073-2
• Support Opportunities: Regular Research Grants
• Start date: March 01, 2025
• End date: February 29, 2028
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Luciana Bolsoni Lourenço
• Grantee: Luciana Bolsoni Lourenço
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated researchers: DOMINGOS DE JESUS RODRIGUES ; Juan Martín Ferro ; Marcos Gridi-Papp
• Associated scholarship(s): 25/07690-0 - Investigation of the dynamics of sex chromosomes and karyotypic evolution in species of the genus Engystomops (Anura, Leptodactylidae), BP.DR; 25/07768-9 - Comparative analysis of the molecular composition of the nucleolus organizer regions in the Physalaemus cuvieri - Physalaemus ephippifer species complex, BP.MS

Abstract

The role of chromosomal variations in speciation processes is widely supported by theoretical models, but empirical data on chromosomal speciation are still scarce. Groups of lineages undergoing divergence that still exhibit contact zones and evidence of hybridization represent valuable models for studies on this topic. In this project, we will focus on two species complexes of Anura with broad geographical distribution and multiple genetic lineages, aiming to explore the role of chromosomal variations in speciation: the Physalaemus cuvieri - P. ephiphifer and the Engystomops freibergi - E. petersi complexes. Initially, we will complement the cytogenetic analyses of these groups, filling important gaps in knowledge. In the case of the first complex, we will analyze females from the lineage known as L3 to assess whether there is sex chromosome heteromorphism in this lineage. We will also conduct cytogenetic analyses of specimens from Mãe do Rio/Aurora do Pará and the central region of Brazil to deepen the characterization of contact zones between different genetic lineages of this complex. As the NORs are particularly variable and informative in this group and, in P. ephippifer, they were found to be associated with at least four satellite DNAs, we will also investigate the association of NORs with satellite DNAs in the other lineages of this species complex. To this end, we will analyze the repetitive fraction of the genome of L1 and L3 and perform chromosomal mapping of the sequences of interest. Regarding E. freibergi - E. petersi, with to refine the comparison between the distinct karyotypes, we will describe the karyotype of a new population from this group and search for new chromosomal markers based on the genomic analysis of E. freibergi and E. pustulosus. With all cytogenetic data in hand, we will identify the lineages with the greatest chromosomal variation in each group. We will then use mitochondrial DNA sequences to test the hypothesis that karyotypic variations may have accelerated the rate of evolution in these groups. For this purpose, the predicted diversity calculated in the absence of the tested event (i.e., karyotypic variation) will be compared with the observed diversity using the cross-validation method proposed by Moore & Donoghue (2009). In this way, we aim to identify the role of chromosomal variations in the diversification of the selected anurans. (AU)