Genetic structure and clonal diversity of jatobá-do-cerrado (Hymenaea stigonocarpa Mart. ex Hayne) in two populations of the Cerrado in the State of São Paulo

Author(s)

Maria Andréia Moreno

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2009-06-26

Examining board members

Paulo Yoshio Kageyama; Mario Luiz Teixeira de Moraes; Maria Imaculada Zucchi

• Advisor: Paulo Yoshio Kageyama

Abstract

This study aimed to evaluate the population and genetic structure of Hymenaea stigonocarpa Mart. ex Hayne in two areas of Cerrado in the State of São Paulo. For this, eight nuclear microsatellite (SSR) primers from Hymenaea courbaril and five universal chloroplastidial microsatellite primers (cpSSR) were transferred from Hymenaea coubaril to H. stigonocarpa. This study answered the assumptions regarding restricted seed dispersal, vegetative propagation and the existence of the populations evolutionary viability in the studied conservation units. This study was conducted in two protected areas managed by the Forest Institute State of São Paulo and represent some of the last protected remnants of Cerrado in the State with contrasting physiognomies and history. The 68 trees of H. stigonocarpa on the population located in the Ecological Station of Itirapina (ESI), Itirapina, S.P., were spatially clumped. Using SSR markers only 18 different genotypes (genets) were found, showing the existence of vegetative propagation in ESI. Despite the limited number of genets in the area, this population showed an excess of heterozygotes. Even so, the minimum viable area for conservation ( AMV ) was greater than the total area of the ESI due to low density of individuals. The paternity analysis using all the available seeds in ESI (n = 71) revealed that 42.46% of pollen donors were outside the sampled area and the effective neighborhood size of pollination was 1283 ha demonstrating the importance of surrounding areas and the expansion of the protected area. There was pollen donor dominance and the average distance of pollination was 2325 m, ranging from 0.35 to 3570 m. Furthermore, the markers cpSSR revealed a strong founder effect, with the existence of a single haplotype. In contrast to the ESI, the population studied in the Ecological Station of Assis and in the Assis State Forest (EEA), had 47 trees, all genets. The use of SSR markers in the population of the ESA revealed a high and significant fixation index ( f = 0177), associated with a significant spatial genetic structure (SGS) ( xy q = 0075) up to 750 m. The SGS was originated by a limited seed dispersal, as evidenced by the use of cpSSR markers. The high genetic divergence shown by SSR markers and the number of private haplotypes found in the population of the ESA are reasons to consider each population independent units for management (IUM) and at the same time an Evolutionary Significant Unit (ESU). These designations mean that, in despite of the populations of the ESI and ESA have insufficient effective sizes ( e N ) and AMV for the maintenance of H. stigonocarpa inbreeding level in the short term, the specific location of these units allowed to include different gene pools, important in starting an adaptive-evolutionary conservation. Thus, programs aimed at forest restoration or breeding of H. stigonocarpa shall address each ESU genotypes. Moreover, the collection of seeds for conservation should have a minimum distance of 750 m among trees, when these are not clumped. (AU)