Ecological principles can be studied in the laboratory as well. Perhaps you can think of some
ways in which some aspects of ecology can be isolated in the lab. Statistical analysis is also
used for analyzing both field and laboratory data. Finally, ecologists often use computer
simulations to model complex ecological systems and to help predict how future environ-
mental changes can affect a system. Can you think of some possible environmental change
in the future that could be studied?
Organisms and Environments
All organisms have the abilities to grow and reproduce, properties which require materials
and energy from the environment. The organism’s environment includes physical properties
(abioticfactors), such as sunlight, climate, soil, water and air, and biological properties
(bioticfactors), which are the other living organisms, both of the same and different species,
which share its habitat. In other words, the biotic factors live in the same area. Biotic and
abiotic factors will be further discussed in the Ecosystems lesson.
Anexampleofhowbioticfactorsinfluencetheenvironmentinwhichanorganismlivescanbe
seen in the primitive atmosphere. The first photosynthesizing organisms on Earth produced
oxygen. This led to an oxygen-rich atmosphere, which caused life forms for which oxygen
was toxic to die, and other organisms which needed oxygen to evolve.
Levels of Organization in Ecology
Ecology can be studied at a wide range of levels, from the smallest unit, at the individual
level, to the largest, or most inclusive, thebiosphere(the portion of the planet occupied
by living matter (Figure23.2)) (Table(23.1) ). In between the individual level and the
biosphere, from smallest to largest, are thepopulation(organisms belonging to the same
species that occupy the same area and interact with one another) level, thecommunity
(populations of different species that occupy the same area and interact with one another)
level, and the ecosystem (a natural unit composed of all the living forms in an area,
functioning together with all the abiotic components of the environment (Figure23.3))
level.
Table 23.1: Ecological RangeLevel Definition
population organisms belonging to the same species
that occupy the same area and interact with
one another
community populations of different species that occupy
the same area and interact with one another