Rafael Plá Matielo Lemos

Genetic structure and internal gene flow in populations of Schinus molle (Anacardiaceae) in the Brazilian Pampa

One of the most important aspects for population ecology and evolution is to understand the connectivity between individuals and their groups. In this study, amplified fragment length polymorphism (AFLP) markers were employed aiming to examine genetic diversity, spatial genetic structure, and internal gene flow of nine populations of Schinus molle across the Brazilian Pampa. The dispersal capacity of S. molle in the Brazilian Pampa, the implications of the forest fragmentation to species genetic structure, and the impact of the actual genetic structure of the species to its conservation and management were investigated. AFLP markers revealed low genetic diversity and clear genetic structure among populations. Significant fine-scale spatial genetic structure at short distances was observed in all populations. Estimates of gene dispersal distance suggest that the dispersion capacity of this species is larger than the area covered by the studied populations. However, fragmentation hampers the gene flow among populations. The management of S. molle natural occurrence in this biome seems to be simple considering the species plasticity. The conservation of the species genetic resource depends on maintaining the extant forest patches and promoting their connectivity.

Characterization of Plastidial and Nuclear SSR Markers for Understanding Invasion Histories and Genetic Diversity of Schinus molle L.

Invasive plant species are expected to display high dispersal capacity but low levels of genetic diversity due to the founder effect occurring at each invasion episode. Understanding the history of invasions and the levels of genetic diversity of such species is an important task for planning management and monitoring strategy for these events. Peruvian Peppertree (Schinus molle L.) is a pioneer tree species native from South America which was introduced in North America, Europe and Africa, becoming a threat to these non-native habitats. In this study, we report the discovery and characterization of 17 plastidial (ptSSR) and seven nuclear (nSSR) markers for S. molle based on low-coverage whole-genome sequencing data acquired through next-generation sequencing. The markers were tested in 56 individuals from two natural populations sampled in the Brazilian Caatinga and Pampa biomes. All loci are moderately to highly polymorphic and revealed to be suitable for genetic monitoring of new invasions, for understanding the history of old invasions, as well as for genetic studies of native populations in their natural occurrence range and of orchards established with commercial purposes.