8.1 What is Ecology?
Ecology is the study of the interactions of living organisms with their environment. A central goal of ecology is to understand the distribution and abundance of organisms across the Earth. Achieving this goal requires integrating knowledge from many scientific disciplines, both within and beyond biology – including biochemistry, physiology, evolution, biodiversity, molecular biology, geology, and climatology. Some ecological research even incorporates chemistry and physics, and frequently relies on mathematical models.
Levels of Ecological Study
When a discipline such as biology is studied, it is often helpful to subdivide it into smaller, related areas. For instance, cell biologists interested in cell signalling need to understand the chemistry of the signal molecules (which are usually proteins) as well as the result of cell signalling. Ecologists interested in the factors that influence the survival of an endangered species might use mathematical models to predict how current conservation efforts affect endangered organisms. To produce a sound set of management options, a conservation biologist needs to collect accurate data, including current population size, factors affecting reproduction, habitat requirements, and potential human influences on the endangered population and its habitat.
A habitat is the natural environment in which an organism lives. It includes all the resources and conditions the organism needs to survive, grow, and reproduce. These conditions are shaped by both biotic factors (the living components of the environment, such as plants, animals, fungi, and microbes) and abiotic factors (the non-living components like temperature, sunlight, water, soil, and air).
Within the discipline of ecology, researchers work at four specific levels, sometimes discretely and sometimes with overlap: organism, population, community, and ecosystem (Figure 8.1.1)
Organismal Ecology
Organismal ecology focuses on the adaptations that enable individuals to live in specific habitats. The distribution of organisms is limited by the abiotic conditions they can tolerate.
For example, the woodland caribou (Rangifer tarandus caribou) is specially adapted to life in Canada’s boreal forests. These caribou have large, fur-covered hooves that help grip the ice and dig through snow for food. They rely heavily on lichens, which are slow-growing and found in mature forests. Their seasonal migrations and calving behaviors are also shaped by environmental conditions.
An ecologist studying woodland caribou at the organismal level might ask:
- What are the limits of temperature that woodland caribou can tolerate?
- What is the maximum snow depth that woodland caribou can tolerate before their movement or foraging is significantly affected?
- What environmental factors do woodland caribou use to select calving sites to reduce predation?
Population Ecology
A population is a group of interbreeding individuals of the same species living in the same area at the same time. Population boundaries may be natural (like rivers or mountains) or artificial (such as roads or buildings). Population ecology focuses on the number of individuals in a population and how and why that number changes over time.
Woodland caribou populations have declined in many parts of Canada due to habitat fragmentation, industrial development, and increased predation. Because they are listed as threatened under Canada’s Species at Risk Act, ecologists monitor their numbers closely. Researchers might also use mathematical models to predict population trends under various conditions.
An ecologist studying woodland caribou at the population level might ask:
- How has the population size of woodland caribou changed over the past several decades in different regions of Canada?
- What impact does road construction have on the movement patterns and connectivity between caribou populations?
- How does habitat fragmentation affect the genetic diversity of isolated caribou populations?
Community Ecology
A community includes all the different species living in a particular area and the interactions among them. Community ecology focuses on interspecific interactions, which are interactions that occur between different species.In Canada’s boreal forest, woodland caribou share their habitat with species such as moose, wolves, and black bears. Human activities like logging and road construction have altered these landscapes, creating younger forests that are more suitable for moose. The growing moose population supports a larger wolf population. These wolves also prey on caribou. Community ecologists might study how these predator-prey dynamics influence caribou survival and how restoring natural forest patterns could help rebalance these interactions.
An ecologist studying woodland caribou at the community level might ask:
- How does the presence of moose influence wolf population density and predation rates on woodland caribou?
- What are the effects of increased predator abundance on caribou behavior and habitat use?
Ecosystem Ecology
An ecosystem is a community of living organisms (biotic components) interacting with the non-living elements (abiotic components) of their environment. Ecosystem ecology focuses on how energy flows and nutrients cycle through these biotic and abiotic systems. Abiotic factors include elements such as air, water, soil, temperature, and sunlight.
Woodland caribou live in ecosystems dominated by coniferous forests, peatlands, and wetlands. These ecosystems store large amounts of carbon and play a role in regulating climate. The slow decomposition rates in these cold, wet environments affect nutrient cycling and plant growth.
Ecosystem ecologists might study how climate change and industrial development alter the carbon balance of boreal forests, or how changes in soil moisture affect lichen availability for caribou.
An ecologist studying woodland caribou at the ecosystem level might ask:
- What impact does industrial development have on nutrient availability in caribou habitats?
- How do changes in permafrost associated with global warming affect hydrology in caribou habitat?
- How does atmospheric pollution (e.g., acid rain or nitrogen deposition) influence the growth and distribution of lichen species?
Knowledge Check
Text Description
- How does road construction impact gene flow between caribou populations?
- How do caribou choose calving sites to reduce predation risk?
- What is the effect of nitrogen deposition on lichen growth?
- How do moose populations affect wolf densities?
- Studying how wolves interact with caribou and moose.
- Examining how lichens respond to climate change.
- Monitoring caribou numbers and predicting future population trends.
- Exploring how caribou select habitats based on snow depth.
- Overharvesting of lichens
- Introduction of invasive species
- Logging and road construction
- Air pollution from mining
- What is the snow depth tolerance of woodland caribou?
- How does permafrost thaw impact wetland hydrology?
- How many caribou inhabit a given forest region?
- How do moose compete with caribou for space?
- By adjusting migration routes in response to wolf populations
- By relying on mature forests with slow-growing lichens and using fur-covered hooves to navigate snowy terrain
- By increasing birth rates in response to declining populations
- By forming larger herds to confuse predators
6. Drag and Drop Activity #6
Match the phrase to its corresponding definition
Answer options: Community Ecology, Population Ecology, Ecosystem Ecology, Organismal Ecology
- Level of ecology concerned with the adaptations of individuals
- Level of ecology concerned with groups of individuals of the same species
- Level of ecology concerned with groups of different species living together
- Level of ecology concerned with both the biotic and abiotic factors influencing things living together
Answers:
- b
- c
- c
- b
- b
- 1 = Organismal Ecology, 2 = Population Ecology, 3 = Community Ecology, 4 = Ecosystem Ecology
OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Create 5 multiple-choice questions using the following content
“The Scope of Ecology” from Principles of Biology by Lisa Bartee, Walter Shriner & Catherine Creech is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.
