Testing the species boundaries and geographic limits of Ceratophrys aurita and Ceratophrys joazeirensis using high-throughput sequencing methods.

• Grant number: 25/05468-8
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: September 30, 2025
• End date: May 29, 2026
• Field of knowledge: Biological Sciences - Zoology
• Principal Investigator: Célio Fernando Baptista Haddad
• Grantee: Diego Bueno Villafañe
• Supervisor: Arley Camargo Bentaberry
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Institution abroad: Universidad De La República, Sede Rivera, Uruguay
• Associated to the scholarship: 23/08932-1 - Diversification and evolutionary history of horned frogs Ceratophrys aurita (Raddi, 1823), Ceratophrys cranwelli Barrio 1980, Ceratophrys joazeirensis Mercadal and Barrio, 1986 and Ceratophrys ornata (Bell, 1843) (Anura, Ceratophryidae), BP.DR

Abstract

The genus Ceratophrys (Anura: Ceratophryidae) includes terrestrial anuran amphibians with unique morphological characteristics and a broad distribution in South America. The species Ceratophrys aurita and C. joazeirensis, distributed in the Atlantic Forest and Caatinga, respectively, present taxonomic challenges due to their similar morphology and low genetic differentiation. Although previous studies have confirmed the monophyly of the C. aurita + C. joazeirensis clade, limitations in sampling and the resolution power of the genetic markers used hinder a detailed understanding of their evolutionary histories.To date, our unpublished results, obtained from the most extensive geographic sampling conducted for these species, have revealed low support for the basal branches of the clades of both species, especially in C. aurita. These findings suggest a more complex evolutionary history than previously estimated, raising hypotheses about possible scenarios of recent divergence, hybridization, or introgression events. These indications highlight the need for a thorough reassessment to address the pending taxonomic and evolutionary issues.In this context, this project aims to reassess the species boundaries between C. aurita and C. joazeirensis, define their taxonomic status, and investigate the evolutionary events that shaped their diversification. For this purpose, the most extensive geographic sampling obtained to date for both species will be used, along with high-resolution genomic data generated through the ddRADseq method. This approach allows access to thousands of SNPs, ideal markers for examining both shallow and deep divergences, providing a robust basis for testing the existence of distinct taxonomic entities and exploring evolutionary interactions since their divergence.Furthermore, the project will investigate crucial aspects of population genetic structure, such as historical and contemporary gene flow, potential hybridization and introgression events, as well as demographic dynamics associated with paleogeographic and climatic changes in the Atlantic Forest and Caatinga regions. The correct delimitation of C. aurita and C. joazeirensis will not only contribute to a better understanding of their biology and evolution but will also establish a stronger foundation for future research and more well-founded conservation strategies. This work is particularly relevant because little is known about both species, including basic aspects of their natural history, geographic distribution, and even their conservation status.The work will consist of extracting DNA from the available samples, followed by training and the development of a protocol for preparing libraries using the ddRADseq technique, which will be employed for next-generation sequencing on the Illumina platform. Additionally, I will be trained to process raw sequencing data and generate SNP data matrices using the necessary bioinformatics tools to achieve the project's objectives. The Laboratory of Biogeography and Evolution (University of the Republic, Rivera, Uruguay) is fully equipped to carry out these activities and has a highly skilled team familiar with the required protocols. Dr. Arley Camargo Bentaberry, a regional reference in ddRADseq methods, will oversee the process and contribute his extensive experience in implementing and optimizing these techniques. (AU)