The geometry of decline: testing the abundant-center hypothesis for spatial and temporal trends of abundance of Neotropical herpetofauna

• Grant number: 24/10038-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: August 01, 2024
• End date: March 31, 2025
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Marcio Roberto Costa Martins
• Grantee: Filipe Alexandre Cabreirinha Serrano
• Supervisor: Ana Sofia Luis Rodrigues
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Centre d'Ecologie Fonctionnelle & Evolutive (CEFE), France
• Associated to the scholarship: 23/06999-1 - Drivers of vulnerability to extinction of Brazilian amphibians: insights for conservation, BP.PD

Abstract

The abundance of vertebrates is declining at a global scale and quantifying these declines is essential to design better conservation strategies, especially in the Neotropical region where these declines are stronger. The abundance of populations has been suggested to be naturally lower at the edges of their distributions compared to the center, which is commonly known as the 'abundant-center hypothesis'. Despite tested for several groups with mixed results, this hypothesis has not been widely tested for amphibians. Furthermore, changes in abundance over time have not been incorporated in the 'abundant-center hypothesis', even though populations at the edge may be more vulnerable by being in less suitable habitat. Herein, we use published databases of abundance and density to test whether the abundance of Neotropical amphibians, one of the less studied but more threatened taxonomic groups, decreases with distance to the center. Furthermore, we test if temporal changes in abundance are stronger for populations at the edge of species distribution. For both approaches, we incorporate ecological traits and correct for phylogenetic relatedness. By understanding how and where the abundance of amphibians is decreasing, we can more efficiently design and inform conservation actions, with such analyses being potentially applied to other taxonomic groups.