Ecology is the scientific study of relationships between living organisms and their environments. It examines how species interact with each other and with the physical world around them - from microscopic bacteria in soil to the cascading effects of climate change on global ecosystems. Ecology underpins nearly every environmental science career and discipline.
If you've ever wondered why a forest looks the way it does, how predator and prey populations stay in balance, or what happens to an ecosystem when a key species disappears, you're already thinking ecologically. Ecology is one of the most foundational fields in environmental science, and understanding it opens the door to dozens of rewarding careers and research paths.
This guide covers what ecology actually is (and what it isn't), its history, its many sub-disciplines, and where the field is heading in the years ahead.
Table of Contents
- What Is Ecology?
- A History of Ecology
- The Sub-Disciplines of Ecology
- The Future of Ecology
- The Challenges Ahead
- Emerging Technologies
- Frequently Asked Questions
- Key Takeaways
What Is Ecology? An Introduction to the Field
Ecology studies organic life, examining such elements as spatial distribution, abundance, and each organism's relationship with its environment. This includes interactions with other organisms within that environment - essentially their "interrelatedness" as a functioning network.
The word "ecology" comes from the Greek, meaning roughly "house study" or "living relations study." That's an apt description: ecology is the study of relationships between those who occupy a shared home, whether that home is a tidal pool, a temperate forest, or the entire biosphere.
Although closely associated with conservation and environmentalism today, ecology is a far broader discipline than most people realize. It includes aspects of biology, botany, zoology, genetics, bacteriology, chemistry, and physics. An ecological study can examine bacterial cells, gut flora, aphid populations on a single plant, or the planetary-scale impact of rainforests on Earth's carbon cycle.
Its main areas of focus include:
- The biological processes that drive life, including adaptation and evolution
- Distribution, abundance, spatial concentration, and biodiversity
- How and why ecosystems form, shift, or collapse under external pressures
- The movement of energy and materials through an ecosystem over time
A History of Ecology
Antiquity to 1900
Despite being closely associated with environmental sciences, the philosophy of relationships between biological systems - which is the actual definition of ecology - emerged as a formal discipline only in the late 19th century. Some argue awareness of species relationships began with Aristotle, though his writings on the matter are largely lost. Aristotle's student Theophrastus described relationships between plants and animals, but from a philosophical rather than scientific perspective.
The first recognizable ecological study is arguably the Park Grass Experiment, which began in 1856 and is still ongoing today. Around 150 papers have been published on the study, contributing to major areas of biodiversity research and agricultural science. Two of Charles Darwin's contemporaries also made pivotal contributions. His friend Alfred Russell Wallace examined the geography of animal species, while Johannes Eugenius Warming studied the effects of fire, temperature, and other abiotic influences on plant communities. Warming is now credited with creating Botanical Geography - today known as a division of ecology - and his work helped shift the scientific community toward understanding how environmental factors shape the biological systems within them.
It was also during the late 19th and early 20th century that researchers began to grapple seriously with the ecological consequences of industrialization, deforestation, and colonial-era land use.
20th Century to the Modern Era
Ecology became a true scientific discipline in the 20th century. The concept of the "biosphere" - the idea that Earth and its biological systems form an interconnected whole - was formalized during this period. Vladimir I. Vernadsky, a Russian geologist who relocated to France around the time of the Russian Revolution, wrote extensively about the biosphere in his 1926 study The Biosphere. The term itself had been coined earlier by Austrian geologist Eduard Suess in 1875.
To many, ecology didn't truly begin as a discipline until Arthur Tansley coined the term "ecosystem" in the early 20th century. Tansley's contribution was in framing ecology as a philosophy applicable across scientific disciplines, which allowed it to be adopted into theories far beyond environmental science. Around the same time, American botanist Henry Chandler Cowles founded the concept of "dynamic ecology" through his study of the Indiana Dunes at Lake Michigan, demonstrating how environmental influences change a landscape over large time periods.
Later, British-born ecologist G. Evelyn Hutchinson transformed ecology into an applied science as well as a theoretical one. His work shaped many subdisciplines, including biogeochemistry, entomology, genetics, limnology, and population dynamics theory.
The Sub-Disciplines of Ecology
Ecology is best understood as an umbrella term. Despite its strong associations with environmental studies, it encompasses dozens of subdisciplines - some directly focused on the environment, some not. Here's an overview of the most significant.
Applied Ecology
Applied ecology uses ecological principles to identify and solve real-world problems, balancing effective land use with conservation. It's an interdisciplinary field drawing on genetics, animal and plant biology, conservation biology, and environmental management. The aim is to examine the impact of human activity on landscapes and encourage land use practices that don't damage wildlife or ecosystems.
Biogeochemistry
Biogeochemistry fuses ecology with physics and chemistry, examining how biological materials affect global chemistry and vice versa. It focuses on the natural physical cycles of energy and matter on Earth - specifically the roles of nitrogen, oxygen, and carbon as they move through the lithosphere, biosphere, and atmosphere. Understanding these cycles is essential for tracking climate change and pollution impacts.
Biogeography
Biogeography studies the geographic distribution of species and their related ecosystems across geological time. It draws on environmental biology, evolutionary biology, climate science, and geology to answer a core question: why do biological species thrive in one ecological system but not another? A botanist studying plant distribution across climate zones, for example, is working within this sub-discipline.
Chemical Ecology
Chemical ecology examines how biological species use chemicals - not how humans introduce chemicals into the environment. This includes chemical defense mechanisms (like capsicum in chili plants), predator-deterrent sprays (like those of skunks), pheromones for mate attraction and territorial marking, and the chemistry of animal digestive systems. It also looks at how those chemicals affect surrounding ecosystems.
Community Ecology
Community ecology studies how groups of species interact with each other and their environment - predators and prey, symbiotic relationships, co-operation between unrelated species, and coevolution. It's a powerful lens through which to examine biodiversity, and it can apply to human communities as well as animal ones. Wildlife biologists frequently draw on community ecology principles when studying population dynamics in mixed-species environments.
Conservation Ecology
This is the subdiscipline most people picture when they hear the word "ecology," though it's only one part of the larger field. Conservation ecologists examine how changing practices in an environment might reduce the risk of species extinction. They work closely with conservation biologists, though ecologists focus more on the broader impact of the environment, biodiversity, and natural resources as an interconnected whole. Learn more about what ecologists do and how conservation fits into the wider field.
Ecophysiology
Also known as environmental physiology or physiological ecology, this subdiscipline examines how environmental conditions affect a species' physiology. It has some overlap with evolutionary biology, looking at how environmental forces drive adaptation rather than random genetic drift. Charles Darwin's famous observations of the Galápagos finches are an early example of ecophysiological thinking in practice.
Ecotoxicology
Ecotoxicology examines the ecological role of toxic materials on biological systems - at the individual, species, community, and biosphere levels. Rather than focusing on pollution from a medical perspective, practitioners examine broad, long-term effects on the environment. This field's work contributed to landmark legislation, including the Clean Air Act and the formation of the EPA. Rachel Carson, a marine biologist and author of Silent Spring (1962), is credited with founding this area of study.
Evolutionary Ecology
Evolutionary ecology - also called ecoevolution - fuses biology, evolution, and ecology to consider how environmental pressures shape species evolution. This can include sudden temperature shifts, vegetation changes in newly colonized areas, predator-prey dynamics, and population pressure. It considers evolution at both the individual and community level, examining how natural selection plays out within a specific ecological context.
Fire Ecology
Fire ecologists study the Earth's relationship with wildfire - how fires start and end, why they occur in certain areas, their frequency and intensity, and the ecological history of wildfire in a given landscape. Despite common perception, many ecosystems depend on periodic fire to regenerate. Fire ecology is increasingly important as climate change extends fire seasons across the western United States and other regions.
Functional Ecology
Functional ecology examines the roles specific species - or groups of species - play in maintaining ecosystem balance. This includes predator-prey interactions, interdependencies, and the downstream consequences when a key species is removed. A plant ecologist studying the role of wildflowers in sustaining bee populations, for example, is working within functional ecology.
Global Ecology
Global ecology studies the entire planet as a single ecosystem, examining how micro and macro events interact across regions. Events in one area - a large volcanic eruption, mass deforestation, ocean temperature shifts - can have local, regional, or worldwide consequences. Global ecology addresses macroecological questions about climate change, ocean acidification, and the human impact on planetary systems.
Human Ecology
No species has transformed its habitat quite like humans. Human ecology takes an interdisciplinary look at the ecological impact of human life across our 200,000-year history - from deforestation for agriculture and urbanization, to the crossbreeding of animal and plant species, to our ongoing modification of natural environments. It examines how humanity's ecological dominance has reshaped the biosphere, and what that means for other living systems.
Landscape Ecology
Landscape ecology examines interactions between discrete elements within a single landscape type - its structure, composition, and functions within a wider ecology. A landscape can be a mountain range, a freshwater floodplain, or a wetland. This field seeks to understand how the spatial arrangement of habitats within a landscape affects species movement, biodiversity, and ecosystem function.
Macroecology
Between landscape ecology and global ecology lies macroecology - the study of large-scale ecological phenomena spanning multiple geographic locations without reaching planetary scale. An example: the ecological disruption caused by the 2010 Eyjafjallajökull eruption in Iceland, which affected weather patterns, air traffic, and ecosystems across a significant portion of the northern hemisphere.
Marine Ecology and Aquatic Ecology
Marine and aquatic ecology examines the relationships and interactions of water-based ecosystems - at the biochemical, cellular, individual, and community levels. Practitioners study marine biology, the impact of external pressures (weather systems, land-based pollution) on aquatic ecosystems, and marine geology on biological life and chemical processes. This is a rapidly growing field given the urgency of ocean acidification and reef collapse.
Microbial Ecology
Microorganisms - defined as those too small to see with the naked eye - are vital to all life on Earth. Microbial ecology examines the interactions, ecological needs, and relationships of Archaea, Eukaryota, Bacteria, and Viruses. These organisms exist in every ecosystem on the planet, from the deepest ocean trenches to the highest mountain peaks, and represent some of the oldest lifeforms in Earth's history.
Paleoecology
Paleoecology studies changes to landscapes over geological timeframes, examining extinct animals and plants and exploring ecological reasons for their disappearance. It considers how natural landscape changes - glacier advance or retreat, volcanic activity, sea level shifts - altered biodiversity and drove the migration, contraction, or extinction of species. Paleoecological data increasingly inform predictions about how current climate change may affect species distribution.
Population Ecology
Population ecology is concerned with understanding and predicting the dynamics of a single species within an ecological zone over time. It considers the impact of population numbers on the surrounding environment, including the consequences of predator-prey imbalances where population numbers exceed what the ecosystem can sustain. This applies to wildlife populations as well as human population pressures on ecologically sensitive environments.
Quantitative Ecology
Quantitative ecology applies mathematics, statistics, and increasingly, data modeling to ecological questions. The arrival of Big Data has accelerated growth in this subdiscipline, which uses hard data to answer spatial, demographic, and distribution questions. Computer modeling and simulations now allow ecologists to test hypotheses and predict ecosystem responses at scales and speeds that weren't possible a generation ago.
Restoration Ecology
Restoration ecology examines damage to a landscape - whether from human activity like an oil spill or natural events like volcanic eruptions or flooding - and identifies steps to restore it. Research has shown that concerted restoration efforts can meaningfully reduce extinction rates in affected areas. In the arid western United States, ongoing restoration work is succeeding in combating invasive weed species that threaten native plant communities.
Soil Ecology
Soil is an ecosystem in itself - and a vital one. Soil ecology examines the biological life within soil (bacteria, viruses, fungi, protozoa, algae) alongside the abiological processes that make soil function, including nutrient cycles, acidity, hydration, and the decomposition of organic material. Because the entire food chain ultimately depends on healthy soil, this has become a distinct and increasingly important area of study.
Theoretical Ecology
Like most areas of science, ecology has a theoretical dimension. Theoretical ecologists develop universal theories to underpin ecological understanding regardless of the specific ecosystem in question. Professionals in this area define ecological theory using statistics, mathematical models, computer simulations, and data analysis - providing the conceptual frameworks that applied ecologists test in the field.
Urban Ecology
Around half of the world's human population now lives in urban centers, and that proportion is growing. Urban ecology examines the urban environment not just as a human living unit, but as a complex ecological system - including the networks that connect cities and the non-human species that have made urban environments their home. Rodents, birds, insects, and diverse plant communities all form part of urban ecological systems, and urban designers increasingly draw on ecological principles to improve urban biodiversity.
The Future of Ecology
Ecology and its many subdisciplines are entering both a challenging and exciting period. Accelerating environmental pressures are creating urgent demand for ecological expertise, while new technologies are transforming how ecological data is collected, analyzed, and applied.
The Challenges Ahead
The most pressing challenge is in conservation ecology. Increasing species extinction driven by human-induced climate change is just one factor - we're also seeing measurable impacts of average temperature rises on local, regional, and global ecologies right now. International agreements continue to evolve around carbon emissions targets, and ecologists are at the forefront of modeling what further warming will mean for specific ecosystems.
Ocean acidification is already damaging aquatic ecologies, degrading coral, and affecting the biological life dependent on those ecosystems. Biodiversity loss from habitat clearance - making way for farmland or urban development - creates imbalances between predators and prey and removes vital food sources across the food chain. And access to water, or water scarcity, underpins many of these problems: drought and wildfire events in California in recent years illustrate how water stress amplifies ecological vulnerability across entire regions.
Ecological damage in the developing world is another concern. As previously low-income countries improve their economies, developers are clearing natural landscapes for urban centers, factories, and infrastructure. Balancing these legitimate economic needs against the global ecology is expected to remain a central tension in international trade and climate agreements for decades to come.
Emerging Technologies and Advances in Ecology
New technologies are fundamentally changing how ecological work is done. The biggest shift has been the arrival of Big Data. The Long Term Ecological Research Network, established in 1980, now makes available more than four decades of data sets from long-term ecological studies. Cloud access means researchers can examine and synthesize findings more thoroughly and faster than ever before.
Geographic information systems (GIS) have also transformed conservation ecology, allowing geographic data sets to be plotted into maps and manipulated to show almost any required information. Graphic data presents complex findings in forms that non-experts - including policymakers and the general public - can understand and act on. Coupled with modern remote sensing technology, GIS now allows researchers to track environmental changes and map species movement at scales previously impossible.
Citizen science and crowdsourced data are also growing in importance. By engaging the public in data collection, researchers can gather information at a volume and geographic scale that no single research team could achieve independently. This democratization of ecological data collection is opening new avenues of inquiry across nearly every subdiscipline.
Frequently Asked Questions
What is the difference between ecology and environmental science?
Ecology is one branch within the broader field of environmental science. Ecology specifically studies the relationships between organisms and their environments - the biological interactions and ecological processes that shape ecosystems. Environmental science is a wider, more interdisciplinary field that also includes chemistry, geology, policy, and human dimensions of environmental problems. Many environmental science careers draw heavily on ecological knowledge.
What careers are available in ecology?
Ecology opens pathways into a wide range of careers, including ecologist, conservation biologist, wildlife biologist, marine biologist, environmental consultant, restoration ecologist, and research scientist. Many ecologists also work in government agencies, nonprofits, land management organizations, and academia. The specific career path often depends on your specialization within ecology - marine ecologists follow a different route than fire ecologists, for example.
What degree do you need to work in ecology?
Most ecology careers require at least a bachelor's degree in ecology, environmental science, biology, or a closely related field. Research positions and faculty roles typically require a master's degree or a PhD. Applied roles in conservation, land management, or environmental consulting often begin with a bachelor's degree and develop through field experience. Some government positions have specific degree and certification requirements that vary by agency.
Is ecology a good career path?
Ecology offers meaningful, varied work for people passionate about the natural world - but it's worth going in with realistic expectations. Entry-level positions can be competitive, and fieldwork roles often involve physically demanding conditions. That said, demand for ecological expertise is growing alongside awareness of climate change, habitat loss, and biodiversity decline. Strong quantitative skills, GIS proficiency, and fieldwork experience improve job prospects significantly.
How is ecology connected to climate change?
Ecology and climate change are deeply intertwined. Ecologists study how changing temperatures, precipitation patterns, and ocean chemistry affect species distribution, ecosystem function, and biodiversity. They also contribute to climate modeling, carbon cycle research, and conservation strategies designed to help ecosystems adapt. In many ways, ecology provides the biological and systems-level understanding that climate science depends on to predict and respond to real-world impacts.
Key Takeaways
- Ecology is the science of relationships: It examines how organisms interact with each other and their physical environment - from single cells to global climate systems.
- It's far broader than conservation: Ecology encompasses 20+ subdisciplines, from microbial ecology and soil ecology to urban ecology and theoretical ecology.
- It has deep historical roots: The field developed formally in the late 19th and early 20th centuries, with key contributions from Warming, Tansley, Cowles, and Hutchinson.
- Ecology underpins environmental careers: Whether you pursue wildlife biology, marine science, conservation, or environmental consulting, ecological knowledge is foundational.
- The field is growing in urgency and scope: Climate change, biodiversity loss, and emerging technologies are making ecological expertise more important - and more data-driven - than ever before.
Ready to turn your interest in ecology into a career? Explore environmental science degree programs that build the ecological knowledge, fieldwork skills, and scientific foundation you need - and find funding to help get you there.
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