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How life scientists work with data

Here are some examples of life on earth. They show places teeming with numerous life forms, engaged in intricate interactions. How can we understand this complex planet that humans depend upon for existence?

When faced with the challenge of understanding what is going on in the images above, how do scientists go about making sense of it?  In order to understand what these things are, how they interact and where humans fit into the picture. They investigate, record, form hypotheses, experiment and discuss, using what is called the scientific method.

(Hint: click on the images on this site for full-size versions.)

Life scientists carry out some or all these activities to further our knowledge

ecologist in the field
ecologist in the field
  • research for existing information about their questions
  • collaborate with other scientists
  • collect samples and classify them
  • assign names to novel organisms
  • take measurements of both organisms e.g. size, sex ratios, densities   and environmental factors.g. temperature, oxygen levels
  • investigate and record material movement and energy flows as appropriate
  • form hypotheses
  • perform experiments to test hypotheses
  • draw conclusions
  • publish their work for peer review
  • discuss interpretations arising from their publications
  • arrive at more refined conclusions

Tools of the trade


Dividing organisms into groups based on shared characteristics, and assigning names and linking groups into a hierarchical structure.
This field of study is called taxonomy.

Characteristics were originally based on anatomy; increasingly frequently DNA comparisons are taken into account.

Some basic information about taxonomic classification as used by biologists.

Defining levels of organization

level of organization
A common example of levels of classification

Ecologists designate levels of organization to study

  • Individual - each living organism
  • Population - collection of all the organisms of a given species living in the same ecosystem. It is at this level that we see evolution at work, with organisms changing to better suit their environment, or disappearing if they cannot.
  • Community - all the organisms in a given ecosystem. Within the community level, different species have different roles to play. The most prominent activity is often related to feeding e.g. finches pick up seeds, humming birds gather nectar. They are said to fill different niches. All species have an ecological niche in the ecosystem, which describes how they acquire the resources they need and how they interact with other species in the community. Having niches reduces competition, which helps keep the ecosystem diverse.
  • Ecosystem - habitat (non-living components)  of a community, plus the community itself
  • Biosphere - encompasses all the ecosystems on earth
representation of the biospere
Biosphere Ecology



The planet is considered to consist of 4  interconnected spheres

  • biosphere - as explained above
  • atmosphere -the gaseous mass surrounding the earth, and retained by the planet's gravitational field.
  • hydrosphere - all of the water, ice, and water vapor at or near the surface of the earth, such as the seas, clouds, and the water in and under the ground
  • geosphere - the solid part of the earth consisting of the crust and outer mantle


We will be concentrating on the ecosystem level of organization.

Background on ecosystems concepts

Ecosystems components

An ecosystem is defined as set of components, both living and non-living which interact with each via energy and material flows.

Abiotic (non-living) components include factors such as

abiotic and biotic components of an ecosystem
abiotic and biotic components of an ecosystem
  • water- e.g. state, amount, frequency of refresh, drainage, concentration of salts, rate of movement
  • gases - e.g. nitrogen, oxygen, carbon dioxide, methane in the atmosphere
  • exposure to sunlight -e.g. shading, aspect, duration
  • temperature - range, rate of change, humidity
  • soil components e.g. chemical composition of rocks and minerals present, relative proportions -

Biotic (living) components

  • producers - organisms which can capture an external energy source and bring it into the system
  • consumers - organisms which rely on producers for their energy
  • decomposers - organisms which breakdown the remains of organisms and their waste materials into simpler forms which can be recycled in the system

Ecosystems persist due to the the biodiversity of their biotic components and the relative stability of the abiotic components. Removing biotic elements or drastic changes to abiotic conditions can lead to instability, and in some cases, complete obliteration of the system.

Examples of energy flows in an ecosystem

Energy from an external source (usually the sun in most ecosystems) flows into an ecosystem and then is moved around by the action of organisms.

Examples of materials flow in an ecosystem

Materials move around ecosystems primarily through

  • biotic interactions (e.g. eating and decomposition activities)
  • physical relocation processes ( e.g. evaporation, erosion)

For appreciating material flows, it is necessary to have some understanding of the chemistry of what is flowing and why. A very brief explanation of the required knowledge has been provided as a single page which will open in a new page.

solving problems
putting the pieces together

Checking your understanding

Scores are given but only for personal checking.  Note: They are not being recorded by the system.

food chains and food webs







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