Ecology: The scientific study of the interactions and relationships between organisms and their environment. The term "ecology" was coined by Ernst Haeckel in 1866 (from Greek Oikos 'house' + Logos 'study').
The environment includes:
Ecology studies life at various levels of complexity. These levels are hierarchical:
The habitat is the physical place or environment where an organism lives. It's the organism's "address."
The niche is the functional role of a species in an ecosystem. It includes its tolerance to abiotic factors and its resource needs.
G.E. Hutchinson's Niche: An "n-dimensional hypervolume," where each dimension is a resource or environmental factor.
Ecosystem stability is the ability to withstand disturbances.
| Feature | Autecology (Species Ecology) | Synecology (Community Ecology) |
|---|---|---|
| Unit of Study | Individual or Population (single species) | Community or Ecosystem (multiple species) |
| Focus | Adaptation, life history, population dynamics | Species interactions, community structure, energy flow |
| Example | A study of the water needs of a saguaro cactus. | A study of all plant and animal interactions in the Sonoran Desert. |
Biomes are large-scale ecosystems defined by climate (temperature and precipitation) and dominant vegetation.
| Biome | Climate | Dominant Vegetation | Key Characteristics |
|---|---|---|---|
| Tropical Rainforest | Hot and wet all year. | Broadleaf evergreen trees. | Highest biodiversity. Nutrient-poor soil. |
| Savanna | Hot, with distinct wet and dry seasons. | Grasses with scattered trees. | Supports large grazing mammals. Fire-adapted. |
| Desert | Very dry (low precipitation). Hot or cold. | Succulents, drought-tolerant shrubs. | Water-saving adaptations (e.g., nocturnal). |
| Temperate Grassland | Moderate precipitation, four seasons. | Grasses. | Very fertile soil. Adapted to fire/grazing. |
| Temperate Deciduous Forest | Moderate precipitation, four seasons. | Broadleaf deciduous trees (oak, maple). | Trees lose leaves in winter. Rich soil. |
| Taiga (Boreal Forest) | Cold, with short summers and long winters. | Coniferous evergreen trees (spruce, fir). | Largest biome. Acidic, nutrient-poor soil. |
| Tundra | Extremely cold and dry. | Mosses, lichens, dwarf shrubs. | Permafrost (permanently frozen subsoil). |
The range of an environmental factor (e.g., temperature) within which a species can survive and reproduce.
A genetically distinct population of a species that is adapted to specific local environmental conditions. They can still interbreed with other ecotypes.
A gradual, continuous change in the traits of a species or community composition over a geographical gradient.
This law states that growth is controlled not by the total amount of resources available, but by the scarcest resource (the "limiting factor").
Analogy: The Leaky Barrel. A barrel's capacity to hold water is limited by its shortest stave (plank). It doesn't matter how high the other staves are; water will leak out at the level of the shortest one.
Example: Plant growth in a lake may be limited by the amount of phosphorus, even if nitrogen, sunlight, and water are abundant. Adding more nitrogen will not increase growth; only adding phosphorus will.
This law expands on Liebig's. It states that an organism's success is determined by a range of environmental factors, and that for each factor, there is a minimum, maximum, and optimum level.
In short: Too much of a good thing can be just as bad as too little. (e.g., too much water can be as bad as too little).
These are the components of the environment that affect organisms. They are broadly classified as abiotic (non-living) and biotic (living).
These relate to the soil.
All the living components or interactions.