Ecology
This information is a cumulative record of my notes from an ecology course from my fall semester, 2026.
Ecology comes from the word oikos, Greek for "home" or "place."
Applies statistical approaches to test hypothesises: quantatative values. Sampling bias can be present (i.e. lots of sampling data done in western Europe).
Population distribution
Where each dot represents an individual
Tells us something about the environment.
Driven largely by food supply & other resources.
Richness of species / species diversity
Area 1 has an equal distribution of species, and therefore is more rich, whereas area 2 has one species dominating.
Relative abundance of each species; species evenness, species dominance.
Ecological units
Individual: survival & reproduction; per capita (per individual).
Emphasizes the way in which an individual's morphology, physiology, and behavior enable it to survive its environment.
Population: population dynamics; the unit of evolution.
Individuals of the same species living in the same area. Emphasizes variation over time and space in the number, density, and composition of individuals.
Community: interaction amoung spes[ecoes ;ovongcies; all of the living things; interspecific interactions (i.e. predation); intraspecific interactions (i.e. competition for resources).
Emphasizes the diversity & relative abundance of different kinds of organisms living together in the same place.
Ecosystem: one or more communities of living organisms interacting with their nonliving physical and chemical environments.
Emphasizes the storage and transfer of energy and matter, including the various chemical elements essential to life.
Landscape: multiple ecosystems that are connected by the movement of individuals, populations, matter, and energy.
Concerned with the movement of energy, matter, and individuals between ecosystems.
Biosphere: all of the ecosystems on earth.
Concerned with the largest scale, including movements of air and water - and the energy and chemical elements they contain - over earth's surface.
Principles of ecology
Law of conservation of matter: matter cannot be created or destroyed, can only change form.
Law of conservation of energy: energy cannot be created or destroted, it can only change form; aka law of thermodynamics.
Classifications of organisms via energy
Producer: an organism that uses photosynthesis to convert solar energy into organic compounds or uses chemosynthesis to convert chemical energy into organic compounds, aka an autotroph.
Consumer: an organism that obtains its energy from other organisms, aka heterotroph.
Mixotroph: an organism that obtains its energy from more than one source.
Classification
Predator: kills and partially or entirely consumes another individual.
Parasites: lives & feeds in or on another organism, rarely killing host.
Prasitoid: lives within & consumes the tissues of a living host, eventually killing it.
Pathogen: parasite that causes a disease in its host.
Herbivore: an organism that consumes producers such as plants and algae.
Competition: an interaction resulting in a negative effect between two species that depend on the same limited resource to surviva, grow, and reproduce.
Mutualism: an interaction between two species where each species recieves benefits from the other.
Commensalism: an interaction in which two species live in close association, and one species recieves a benefit, while the other experiences neither a benefir nor a cost.
Relationships
Symbiotic relationships: when two different types of organisms live in a close physical relationship.
Scavanger: an organism that consumes dead animals.
Detritivore: an organism that feeds on dead organic matter and waste products that are collectively known as detrities.
Decomposer: organism that breaks down dead organic material into simpler elements and compounds that can be recycled through the ecosystem.
Habitats
Niche: the range of abiotic and biotic conditions that an organism can tolerate.
Fundamental theory: two species cannot have the same niche because each has unique phenotypes that determine the conditions it can tolerate.
Fundamental niche: all the potential places an organism can live.
Realized niche: where an organism really lives.
Law of 10%: only 10% of energy is transferred to the next trophic level.
Applies statistical approaches to test hypothesises: quantatative values. Sampling bias can be present (i.e. lots of sampling data done in western Europe).
Population distribution
Where each dot represents an individual
Tells us something about the environment.
Driven largely by food supply & other resources.
Richness of species / species diversity
Area 1 has an equal distribution of species, and therefore is more rich, whereas area 2 has one species dominating.
Relative abundance of each species; species evenness, species dominance.
Ecological units
Individual: survival & reproduction; per capita (per individual).
Emphasizes the way in which an individual's morphology, physiology, and behavior enable it to survive its environment.
Population: population dynamics; the unit of evolution.
Individuals of the same species living in the same area. Emphasizes variation over time and space in the number, density, and composition of individuals.
Community: interaction amoung spes[ecoes ;ovongcies; all of the living things; interspecific interactions (i.e. predation); intraspecific interactions (i.e. competition for resources).
Emphasizes the diversity & relative abundance of different kinds of organisms living together in the same place.
Ecosystem: one or more communities of living organisms interacting with their nonliving physical and chemical environments.
Emphasizes the storage and transfer of energy and matter, including the various chemical elements essential to life.
Landscape: multiple ecosystems that are connected by the movement of individuals, populations, matter, and energy.
Concerned with the movement of energy, matter, and individuals between ecosystems.
Biosphere: all of the ecosystems on earth.
Concerned with the largest scale, including movements of air and water - and the energy and chemical elements they contain - over earth's surface.
Principles of ecology
Law of conservation of matter: matter cannot be created or destroyed, can only change form.
Law of conservation of energy: energy cannot be created or destroted, it can only change form; aka law of thermodynamics.
Classifications of organisms via energy
Producer: an organism that uses photosynthesis to convert solar energy into organic compounds or uses chemosynthesis to convert chemical energy into organic compounds, aka an autotroph.
Consumer: an organism that obtains its energy from other organisms, aka heterotroph.
Mixotroph: an organism that obtains its energy from more than one source.
Classification
Predator: kills and partially or entirely consumes another individual.
Parasites: lives & feeds in or on another organism, rarely killing host.
Prasitoid: lives within & consumes the tissues of a living host, eventually killing it.
Pathogen: parasite that causes a disease in its host.
Herbivore: an organism that consumes producers such as plants and algae.
| Type of interaction | Species 1 | Species 2 |
|---|---|---|
| Predation/parasitoidism | + | - |
| Parasitism | + | - |
| Herbivory | + | - |
| Competition | - | - |
| Mutualism | + | + |
| Commensalism | + | 0 |
Competition: an interaction resulting in a negative effect between two species that depend on the same limited resource to surviva, grow, and reproduce.
Mutualism: an interaction between two species where each species recieves benefits from the other.
Commensalism: an interaction in which two species live in close association, and one species recieves a benefit, while the other experiences neither a benefir nor a cost.
Relationships
Symbiotic relationships: when two different types of organisms live in a close physical relationship.
Scavanger: an organism that consumes dead animals.
Detritivore: an organism that feeds on dead organic matter and waste products that are collectively known as detrities.
Decomposer: organism that breaks down dead organic material into simpler elements and compounds that can be recycled through the ecosystem.
Habitats
Niche: the range of abiotic and biotic conditions that an organism can tolerate.
Fundamental theory: two species cannot have the same niche because each has unique phenotypes that determine the conditions it can tolerate.
Fundamental niche: all the potential places an organism can live.
Realized niche: where an organism really lives.
Law of 10%: only 10% of energy is transferred to the next trophic level.