Unraveling cacao: systematics and evolution of Theobroma L. and Herrania Goudot (Malvaceae, Byttnerioideae)

• Grant number: 20/01375-1
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): August 01, 2020
• Effective date (End): June 30, 2023
• Field of knowledge: Biological Sciences - Botany - Plant Taxonomy
• Principal Investigator: José Rubens Pirani
• Grantee: Matheus Colli Silva
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 21/08635-1 - Study of the botanical collections of Theobroma L. and Herrania Goudot (Malvaceae, Byttnerioideae) of the USA, BE.EP.DR

Abstract

Speciation is a key evolutionary process that has generated the enormous species richness levels of South America. Modern methods of molecular systematics and genomic data are currently used to generate high-resolution phylogenies, which are essential for the study of speciation patterns and processes. In this sense, novel studies that assess changes decurrent from different speciation modes at genomic and phenotypic levels are desirable, especially within plants, which are highly diversified organisms still demanding such investigations. Concurrently, studies on the natural history of the rich Brazilian flora - especially on groups acknowledged by their importance in society - are the basis for further technological development and innovation, whereas they represent a recognition of the history and identity of national culture. The "cacao group", composed of Theobroma and Herrania species (Malvaceae, Byttnerioideae), a remarkable group of Amazonian trees with c. 39 species, being c. 18 native or potentially naturalized in Brazil, provides an interesting case study to be performed under those approaches. Phylogenetic relationships between both genera and among their species are being elucidated, but, consequently, infrageneric taxonomic delimitations require a reassessment using modern tools. In this project we propose to undertake a revision of the nomenclatural and taxonomic status of Theobroma and Herrania, particularly focusing on the Brazilian species, associated to an assessment of the morphological evolution and speciation modes in the group. Specifically, (1) given the increasing records in herbarium collections, we will assess the morphology and distribution of current species, critically reevaluating taxonomic delimitations of the group; (2) by using a species-level phylogeny as a backbone for reconstruction of ancestral state characters, we will look for structural synapomorphies and discuss how the evolution of such characters might have occurred in both genera and in their respective sections; (3) by integrating modern methods of population genomics with selected pairs of sister-species, we will evaluate how genetic variation of populations of closely related species under different speciation modes (allopatric and sympatric) behave regarding its divergence levels of genes under selection. This project shall culminate in the publication of at least three manuscripts in high impact scientific journals, as well as an illustrated guide, providing information on the Brazilian species of cacao, which will be detailed described by means of an extensive description. We aim that the results will contribute for improving the knowledge about the structural and genomic heterogeneity of an important Amazonian group, and about the fundamental steps of its diversification within the Neotropical biota. (AU)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

SILVA, Matheus Colli. Unraveling cacaos: systematics and evolution of Theobroma L and Herrania Goudot (Malvaceae, Byttnerioideae). 2023. Doctoral Thesis - Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) São Paulo.