Levels of organization: the concept of hierarchy in ecology, temporal and spatial scales, emerging properties of ecological systems. The ecosystem: abiotic components such as resources and environmental conditions, tolerance and limiting factors, gradients and ecotones, habitats and niches. Open and closed ecosystems. Energy: ecological implications of the principles of thermodynamics. Solar radiation and climate, the ozone screen, energy flow through the biosphere and the biological compartment (Odum model), food grids, solar radiation and climate zones. Biogeochemical cycles: basic elements, the hydrological cycle, water scarcity and rain shadow, carbon cycles, ozone, phosphorus and nitrogen. Ecology of populations and communities: growth models r- and K- strategist, growth of human population, growth in competition, birth rate and mortality. Ecosystem services: examples and case studies. The main terrestrial and aquatic ecosystems. Biodiversity: the measure of wealth in species, evenness and heterogeneity. Human ecology; biological and genetic coevolution. Basics of molecular ecology at population and community level.