Ecological niche modeling and biogeographic barriers in the distribution of rays of the genus Narcine in the western Atlantic Ocean

• Grant number: 25/09897-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: August 27, 2025
• End date: February 26, 2026
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Principal Investigator: Claudio de Oliveira
• Grantee: Beatriz Rochitti Boza
• Supervisor: Andrew Townsend Peterson
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Institution abroad: University of Kansas, United States
• Associated to the scholarship: 21/10936-0 - Study of genetic diversity and kinship analyzes in rays of the genus Narcine (Chondrichthyes: Narcinidae) in the western Atlantic Ocean using SNPs molecular markers, BP.DR

Abstract

Electric rays of the genus Narcine are benthic cartilaginous fishes distributed along tropical and subtropical continental shelves. In Brazil, the taxonomy and geographic distribution of Narcine brasiliensis and closely related species remain unresolved, with increasing evidence suggesting cryptic diversity and morphological overlap. This project aims to investigate the current and potential distribution of Narcine species along the Brazilian coast through ecological niche modeling (ENM). We hypothesize that environmental and geographic features, such as freshwater plumes, salinity gradients and coastal upwelling systems, act as biogeographic barriers that limit dispersal and contribute to population isolation or differentiation. To address this hypothesis, we will compile occurrence records from global biodiversity databases and scientific collections and gather marine environmental data from the MARSPEC and Bio-ORACLE repositories. Occurrence records will be spatially filtered to reduce sampling bias, and environmental variables will be screened for collinearity using variance inflation factor (VIF) analysis. ENMs will be constructed using the MaxEnt algorithm implemented in R, with model complexity optimized via the ENMeval package. Model performance will be evaluated through AUC, omission rates and partial ROC curves, and Jackknife tests will be used to identify the most influential environmental predictors. The expected outcomes will help clarify the spatial structure and potential environmental barriers affecting Narcine species, generating testable biogeographic hypotheses. This internship at the University of Kansas, under the guidance of Dr. A. Townsend Peterson, will provide advanced training in ecological niche modeling and spatial biogeography, directly enhancing the candidate's doctoral research. Ultimately, the project will contribute to species delimitation, conservation strategies and the understanding of evolutionary processes affecting marine biodiversity along the western Atlantic coast.