Searching for the "budding" clades: Exploring the peripheral distribution of cacti found on limestone outcrops

• Grant number: 24/23100-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2025
• End date: April 30, 2027
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Fernando de Faria Franco
• Grantee: Juliana Palmeira Garcia
• Host Institution: Centro de Ciências Humanas e Biológicas (CCHB). Universidade Federal de São Carlos (UFSCAR). Sorocaba , SP, Brazil

Abstract

Lithobiomes are rocky ecosystems that host specialized flora adapted to water stress and high temperatures. In the Cerrado-Caatinga ecotone, they are abundant in limestone outcrops, which are considered azonal lithobiomes. The Neotropical region, encompassing the study area, presents vast biodiversity often linked to geomorphological events during the Miocene and Pliocene and/or Quaternary climatic oscillations. Limestone outcrops are rich in endemic species, likely due to their microhabitats and fragmented distribution as "islands". This project aims to study the genetic diversity of Cactaceae from the subgenus Cereus, specifically species occurring in limestone outcrops in Central-West Brazil. It seeks to expand the sampling area for species such as Cereus calcirupicola, C. pierrebraunianus, C. hexagonus, and populations of C. bicolor, focusing on peripheral and underexplored regions of their distribution. Genetic data will be obtained using the target capture sequencing technique, employing the Cactaceae591 ortholog panel developed by our research group. Phylogenetic reconstructions based on maximum likelihood (IQ-Tree) and coalescent methods (ASTRAL) will infer kinship relationships and position the newly collected localities. Given the significant role of dispersal in the diversification of Cereus species, coupled with the fragmented distribution of limestone outcrops, it is plausible that peripheral localities may have undergone rapid differentiation due to founder effects and continued genetic drift, forming derived monophyletic groups ("budding clades"). In this context, the project can provide new insights into the role of peripheral diversification in cactus species.