Chapter 4 - Ecosystems

Branch of biology that deals with the relations between organisms and their surroundings.
Biological Populations and Communities * Organisms that look similar in genetic makeup, chemistry and behavior belong to the same species. * Organisms of the same species that occupy a specific area are a population. * Populations of different species makes a community * An ecosystem is formed by the interaction of a community of organisms with their physical environment. * These make up the biosphere.
Population Dispersal Patterns * Populations can be dispersed in 3 ways * Clumped * Dense with organisms in some communities. * When resources become scarce, organisms clump together to get those resources. * Random * Little interaction between organisms. * Usually in places consistent with environmental conditions and resources. * Uniform * Uniform spacing between individuals. * Usually arises from competition between resources.
Ecological Niches * Area within a habitat occupied by an organism and includes the function of that organism within an ecological community.

States that the existence, abundance, and distribution of species depends on the tolerance level of each species to both chemical and physical factors.
Limiting Factors * Abiotic factor that limits or prevents the growth of a population.
Resource Partitioning * Resources in an environment are limited. * Some species have evolved to share a certain resource. * Spatial Partitioning - where the competing species use the same resource by occupying different areas within the range of the resource. * Morphological Partitioning - Where they share the species, but have evolved different structures to use the resources differently.
Interactions between species * Amensalism - One species suffers, while the other species is not affected. * Commensalism - One species benefits, while the other species is not affected. * Competition - Prominent in predator-prey relationships. * Mutualism - Two species benefit * Parasitism - One species benefits, the other is harmed. * Predation - Predators hunt and kill prey. * Saprotrophism - Obtain nutrients from dead or decaying plants.
Keystone Species * A species that contributes to a diversity of life and whose extinction would lead to an extinction of multiple species.
Edge Effects * How a local environment changes along some type of boundary or edge.

The ultimate source of energy is the sun. Plants use the sun to produce food.
Photosynthesis * Plants remove carbon dioxide from the atmosphere using photosynthesis. * Plants capture light through chlorophyll. * Oxygen is released into the atmosphere during photosynthesis.
Cellular respiration * Organisms that rely on autotrophs are called heterotrophs. * Cellular respiration is the opposite of photosynthesis. * Glucose in the cells will result in carbon dioxide, water, and chemical energy to be produced.
Ecological Pyramids and 10% rule * During the transfer of energy from one trophic level to the other, only 10% of energy is transferred. * The rest of the energy is lost in the form of heat, metabolic processes, and so on.
Ecosystem Productivity * Of all sunlight that reaches earth, 3% for land plants, and <1% are used for aquatic plants.

Biomes * Biotic Community characterized by the dominant forms of plant life and the climate. * Temperature and precipitation are determinants of biomes.