Efeito da estrutura da paisagem na diversidade genética neutra e adaptativa de Caryocar brasiliense Camb. (Caryocaraceae)
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2018-10-26
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Universidade Federal de Goiás
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Understanding how the human-caused impacts and environmental heterogeneity caused by these changes affect genetic variability is essential for the preservation and planning of animal and plant species management. The main objective of this work was to investigate the effects of landscape changes on diversity and on the adaptive and neutral genetic differentiation of Caryocar brasiliense Camb. (Caryocaraceae), an endemic species and tree symbol of Cerrrado. To do so, we selected five landscapes in regions near Goiânia, in the state of Goiás. Within each landscape, we selected two sample sites. To measure the structure of the landscape, we calculated metrics related to the amount of habitat, connectivity and heterogeneity in buffers of 2km, 4km and 6km that delimited the landscapes and in buffers of 500m around the sampling sites. In each site, we collect fruits of, on average, 10 mother-trees. The seeds of these fruits were measured (longitudinal diameter, transverse diameter and mass) and planted in a greenhouse. Afterwards, we performed character measurements of that were known to be important for the early stages of the plant, such as: percentage and germination time, initial and final heights, height growth rate, initial and final diameters, growth rate of diameter, number of leaves, leaf length and width, fresh and dry mass of root and shoot, root and shoot length. The experiment carried out in the greenhouse allowed us to access the quantitative genetic variability and the evolutionary potential of C. brasiliense in the sampled sites. Thus, in the first chapter, we evaluated the evolutionary potential of C. brasiliense in each sampled site and the effects of landscape structure on quantitative genetic variability. In the second chapter, we analyzed the effects of landscape structure on the diversity and genetic differentiation of adults and juveniles of C. brasiliense and verified if there is a time-lag of the effects of habitat change on the loss of genetic diversity in these landscapes. For this, in the same sites where we sampled the fruits, we collected leaves of adults and juveniles for DNA extraction. From the genotypes obtained using nine microsatellite loci, we access the neutral genetic diversity of C. brasiliense and relate it with the landscape metrics and the population effective size. From these analyzes, we found that functional connectivity was an important variable to explain the patterns observed in the quantitative genetic variability of most of the characters studied, such as those related to seeds, seedling diameter and leaf characters. The amount of habitat (%) was the variable that determined the patterns of genetic-quantitative differentiation for the growth rates of height and diameter, as well as being important to explain the neutral genetic diversity of juveniles. Intermediate levels of the amount of habitat had the highest values of allelic richness and heterozygosity expected for juveniles, while loss of genetic diversity, measured as the difference between adult and juvenile genetic diversity, was influenced by functional connectivity. The reduction of the genetic diversity detected mainly in juveniles evidences a time-lag effect, and corroborates with studies that affirm that species of long life, as C. brasiliense, require a long period of fragmentation so that the changes in heterozigosity are detected. In general, the movement of the pollinators and dispersers, and consequently the gene flow, is an important process in the maintenance of the evolutionary potential and genetic diversity of this species since functional connectivity was the most important variable
influencing the neutral and adaptive genetic diversity of C. brasiliense. In this way, our results demonstrate that restoring or conserving habitat areas in key places that allow the connectivity of the landscape are essential for the conservation of this species.
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AMARAL, T. S. Efeito da estrutura da paisagem na diversidade genética neutra e adaptativa de Caryocar brasiliense Camb. (Caryocaraceae). 2018. 166 f. Tese (Doutorado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2018.