Repeatome analysis of the orchid Epidendrum denticulatum Barb. Rodr.: a comparative analysis between Atlantic Forest and Cerrado populations

• Grant number: 23/05740-4
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2023
• End date: August 31, 2025
• Field of knowledge: Biological Sciences - Botany
• Principal Investigator: Ana Paula de Moraes
• Grantee: Ana Carolina Humberto
• Host Institution: Centro de Ciências Naturais e Humanas (CCNH). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil
• Associated research grant: 21/10639-5 - Center for Research on Biodiversity Dynamics and Climate Change, AP.CEPID

Abstract

Genome size variations are considered one of the main post-zygotic reproductive barriers in plants, and when such variations are observed among populations of the same species, they may indicate an incipient speciation process. Epidendrum denticulatum (2n=52), distributed in the Atlantic Forest and Cerrado biomes, exhibits genome size variation between the two biomes, with Cerrado populations presenting a higher genomic content (2C=5.82pg) compared to Atlantic Forest populations (2C=5.27pg). Previous analyses of the climatic envelope indicated that E. denticulatum initially colonized the southern Brazilian forests (Atlantic Forest), and the migration of this species to the Cerrado in southeastern Brazil occurred soon after the Quaternary period. Environmental changes may have triggered genomic alterations, causing the increase in genome size in Cerrado populations. However, to validate this hypothesis, it is necessary to perform a comparative analysis of the repeat composition of E. denticulatum populations from the two biomes. Thus, the present project aims to answer three main questions: (1) Which sequence(s) is/are responsible for genome size variation among individuals of E. denticulatum populations from the Atlantic Forest and Cerrado?; (2) How do these sequences distribute in the chromosomes of individuals from the Atlantic Forest and Cerrado? (3) Is the divergence time of the sequences present in the Atlantic Forest and Cerrado populations compatible with the results of the climatic envelope analyses, which suggest the migration of E. denticulatum to the Cerrado during the Quaternary period?