Sept 12 2013
What is Ecology?
Interaction between organisms and their environment
Study of the distribution/abundance of organisms
How organisms affect-and are affected by other organisms and their environment
Although similar, an ecologist is not necessarily an environmental activist. Compared with
ecology, environmental science is focused more specifically on how people affect the
environment and how we can address environmental problems
There is no balance to nature. Human impact may prevent returning to the original state and
populations are dynamic. A change in one part of an ecological system can alter other parts of
The ecological community doesn't have a species with only one role to play. Many similar
species are redundant with similar functions. Different species in an area respond in different
ways to changing conditions, a finding at odds with the idea that each species has a distinct
function within a larger tightly knit group of species.
Guiding Principles of Ecology
1. Organisms interact and are interconnected. All organisms are connected to their environment.
Even species that do not interact directly with one another can be connected indirectly by
shared features of their environment.
2. Everything goes somewhere! (movement of energy/nutrients) There is no 'away' into which
waste materials disappear
3. Populations cannot increase in size forever. There are limits to the growth and resource use of
every population, including our own
4. Finite energy/resources result in tradeoffs. If you invest energy into any given strategy you are
taking it away from something else.
5. Organisms evolve/change over time. Evolution is an ongoing process because organisms
continually face new challenges from changes in both the living and non living components of
6. Communities/ecosystems change over time. New species replace others over time
7. Spatial scale matters. Abiotic and biotic environmental conditions can change dramatically from
one place to another, sometimes across very short distances. This variation matters because organisms are simultaneously influenced by processes acting at multiple spatial scales, from
local to regional to global
Ecological Hierarchy (organism->population->community->ecosystem-
Population: Single species in a single area
Community: Variety of species in the same area. They are typically grouped based on location.
They can cover large or small areas and they can differ greatly in terms of the numbers and
types of species found within them
Ecosystem: Community of organisms plus their physical environment
Landscapes: Areas with substantial differences. Typically includes a collection of ecosystems
Biosphere: All of the living organisms on earth plus the environments in which they live (highest
level of biological organization)
Adaptation & Natural Selection
A universal feature of living systems is that they change over time or evolve. Evolution can be
defined as a change in the genetic characteristics of a population over time or as descent with
modification, the process by which organisms gradually accumulate differences from their
ancestors. The following are 2 key evolutionary terms.
Adaptation: Characteristic that improves survival or reproduction. If the adaptation is heritable,
the frequency of the characteristic may increase in a population over time
Natural Selection: Individuals with certain adaptations tend to survive and reproduce at a higher
rate than other individuals
Ex: Antibiotic resistance occurs through what is called natural selection and mutation. The
simple explanation for this process is that when an antibiotic is administered to combat a
certain species of microorganisms it may cause a mutation in the genetic code of some
microorganisms of this specific species causing them to survive the course of antibiotic so, some
of these microorganisms will die and the mutant microorganism will tend to replicate and
spread the mutant gene between them horizontally, and the colony became fully resistant to
that type of antibiotic.
Producers: Capture energy from an external source like the sun and use it to produce food
Net Primary Productivity (NPP): Energy captured by producers minus the amount lost as heat in
cellular respiration. Changes in NPP can have large effects on ecosystem function, and NPP
varies greatly from one ecosystem to another.
Consumers: Get energy by eating other organisms or their remains How Ecosystems Work
Each unit of energy captured by producers is eventually lost as heat. Therefore, energy moves
through ecosystems in a single direction. It cannot be recycled.
Nutrients are continuously being recycled from the physical environment to organisms and back
again. This is known as the nutrient cycle. (nitrogen and phosphorous)
Plants take in the sun's energy. Primary consumers gain energy by eating the plants. When the
consumer dies, the energy is lost and the nutrients end up back in the physical environment.
This allows plants to take up the nutrients and the cycle begins.
Investigator alters one or more features of the environment and observes the effect of that
change on natural processes. (control group and one or more experimental groups)
Can be done at different scales. every ecological study addresses events on some scales but