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Summary Ecology APES1001 MBBCH I
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EcologyIntroduction to Ecology
Population Ecology
Human Population Dynamics
Community Ecology
Interactions
Human activities effects on Nutrient Cycles
Biodiversity threats
Conservation Ecology
,Ecologist → An ecologist is a scientist who studies how animals and plants interact with their
environment
Definitions of Ecology
1. The study of distribution and abundance of living organisms and their interactions
with the environment
2. The scientific study of the processes influencing the distribution and abundance of
organisms, the interactions among organisms, and the interactions between
organisms and the transformation and flux of energy and matter
3. The branch of biology that deals with the relations of organisms to one another and
to their physical surroundings
4. The study of the relationships between plants, animals, people, and their environment,
and the balances between these relationships
5. Concerning interactions among organisms and their biophysical environment,
which includes both biotic and abiotic components
6. Ernst Haeckel was the first person to use the word: he defined ecology as “the study of
the relationship of organisms with their environment”
Main idea of these definitions: “interactions” or “relationships”: The hallmark of ecology
is its encompassing and synthetic view of nature, not a fragmented view.
Why does Ecology matter?
Ecosystem services are used to explain why we should care about the environment, endangered
animals, pollution, or climate change.
Ecosystem services → the benefits people derive from nature
There are 4 broad categories of ecosystem services:
- Provisioning
We obtain our resources from the environment: food (meat/grains), shelter (wood),
energy (fuel wood), medicines
- Regulating
A healthy environment can help to regulate things like floods and wildfires and the
spread of disease (healthy river systems regulate flow to prevent floods, and the
dangerous wildfires in the US at the moment are caused by human disruptions to the
climate and fuel controls on fire)
- Cultural
Ecosystems also provide us with cultural services – A lot of the GDP of South Africa
for example comes from tourists coming here to visit our beautiful natural ecosystems.
, - Supporting
All of these benefits are supported by basic ecological processes, like nutrient cycling,
pollination, and photosynthesis.
Natural Capital → term used to describe the economical value of nature → shows the close
relation between economy and ecology
Ecology and Evolution
Adaptation → evolutionary time Natural selection → ecological time
Ecology is needed to understand evolution. The key process driving evolution is “Natural
Selection” which is an ecological process.
Natural selection is influenced by the interactions between the organism and the
environment at ecological time
One example is the evolution of a disease:
1: Antibiotics are an effective treatment for bacterial infections because they reduce the
population of the bacteria: this is an ecological effect (you will learn about predator prey
dynamics and population growth later in this course).
2: Because there is variation in the bacterial population some of them are more resistant to
the bacteria than others, and these are the ones that are more likely to survive (ecological
effect: interaction between the bacteria and their environment).
3: These antibiotic-resistant bacteria have higher fitness, and therefore reproduce more,
which means their population grows faster than the non-resistant bacteria.
The environment selects for antibiotic resistant bacteria in evolutionary time
The Importance of Scale
Scale is a key concept for ecologists: we study processes that occur at all scales – from the
scale of one individual organism, to the scale of the whole globe.
, We also need to be able to think about what processes change as we move across scales –
how does the interaction of one zebra with its environment change when we are thinking about
a population of zebras, or a community of zebras and their predators?
It is important to think about what scale you are engaging with. Understanding the difference
between an individual, a species, and a community can be quite confusing.
Definitions:
Organismal: How an organism’s structure, physiology and behaviour help them to survive
and reproduce
Population: A group of individuals of the same species living in an area
Community: A group of populations of different species living in an area
Ecosystem: The community of organisms in an area and the physical factors with which those
organisms interact
Landscape: A mosaic of connected ecosystems
Biosphere: The global ecosystem – i.e., the sum of all the planet’s ecosystems and landscapes
These are nested within each other:
Global ecology → landscape ecology → ecosystem ecology → community ecology →
population ecology → organismal ecology
As medical doctors you will often be treating individuals – but the effective treatment for these
individuals depends on the populations they are living in as well as the community and
ecosystems. → could refer to the impact of the social on health of an individual.
Species Distribution
One of the central questions ecologists try to answer is why species occur where they occur?
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