Diversity, genetic structure and domestication of piquiás (Caryocar villosum) in two localities of the Brazilian Amazon

Author(s)

Ana Flávia Francisconi

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2018-12-12

Examining board members

Elizabeth Ann Veasey; Gabriel Dequigiovanni; Karina Martins; Maria Imaculada Zucchi

• Advisor: Elizabeth Ann Veasey

Abstract

Piquiá (Caryocar villosum (Aubl.) Pers.) is a tree species present in the Amazon biome, used mainly for food and timber. Piquiá is incipiently domesticated, and the selection and management by traditional populations may be promoting the continuity of this process. This process began in the Amazon around the end of the Pleistocene and the beginning of the Holocene, and today is being resumed by traditional populations, which cultivate different species in their backyards, among them is the piquiá. Despite its constant use by traditional populations and commercial potential, the diversity and distribution of piquiá have been little studied. The objectives of this study were to analyze the genetic diversity and the genetic structure of piquiás in two different cases. The first was to examine the process of domestication of C. villosum by traditional populations in the Floresta Nacional (FLONA) do Tapajós. The second one was to compare the piquiás populations from the FLONA do Tapajós, in Pará, with another one located in the Reserva Extrativista (RESEX) Rio Ouro Preto, in Rondônia. Sixtyseven individuals from the forest and 26 cultivated in the backyards were genotyped, with the use of seven microsatellite markers, in FLONA. Higher allelic richness, number of alleles, number of effective alleles, private alleles and observed heterozygosity were found in the forest, as well as spatial genetic structuring in backyard individuals, which indicates the domestication of the species, despite the low genetic structure found between the forest/backyards groups in the applied methods. In the second part, 130 piquiás were genotyped, being 92 of Pará, the same ones used in the study of domestication, and 38 of Rondônia. Pará presented higher values for average number of alleles/locus, effective number of alleles, number of private alleles, allelic richness and expected heterozygosity, indicating a possible center of origin of the species. The spatial genetic structure was significant in both localities, suggesting kinship correlations among the individuals, probably due to the forage behavior of their pollinators and dispersers. Genetic structuring between the two localities was observed in all methods, with most of the variation (89%) occurring within populations, according to AMOVA. The differentiation between populations (11%) can be explained by historical factors and high gene flow (Nm = 2,043). According to the Ecological Niche Modeling, used to verify the species distribution, the piquiá occurs predominantly in the Amazonian biome, with best suitability in hot climates, with temperature averages above 18°C, and humid, presenting between 1 and 3 months of drought. (AU)

• FAPESP's process: 17/04868-6 - Genetic diversity and domestication of piquiá (Caryocar villosum) originated from forest and home gardens of the Tapajós National Forest
• Grantee: Ana Flávia Francisconi
• Support Opportunities: Scholarships in Brazil - Master