2. What is ecology?
• It is the study of the rules of engagement
between living and non-living
• It answers questions like:
• Why is the north pole filled with ice?
• Why are mosquitos so common while rhinos are
going extinct?
3. Why??
• Why do some organisms like to live in
one place but not another?
• What makes earth’s different place, like
ecosystems and biomes different from
one another?
6. What is the difference between
environmental science and ecology?
• Both are closely related disciplines
• Environmental science is a broader subject
• Ecology, on the other hand, is usually more focused on how
organisms interact with each other and with their immediate
surroundings
• Ecologists tend to focus their research on very specific
populations of living things
7. Population
• A group of the same organism
• Population ecologists studies why a population grows or shrinks over time,
depending on where they are
8.
9. Ecosystem
• Everything in a community
• Plus the non-living things
• It is a system that includes all living organisms (biotic
factors) in an area as well as its physical environment
(abiotic factors) functioning together as a unit
10. Biomes
• Regions of the world with
similar climate (weather,
temperature) animals and plants
• Organisms have evolved to
adapt similar set of conditions
• There are
terrestrial biomes (land) and
aquatic biomes, both freshwater
and marine
12. Determinants of ecology
• Abiotic elements:
• The climatic factors as temperature, wind, rainfall
• The physical factors as light, fire, pressure, geomagnetism
• Chemical factors as acidity
13. Determinants of ecology (contd.)
• Biotic element:
• The biological (biotic) factors of ecosystem include all the living organisms-
plants, animals, bacteria and viruses. Each kind of living organism found in
an ecosystem is given the name a species.
• Resources are often limited environmental factors which are consumed or
used up and a source of competitions for those organisms. These include
primary producers and predators
14. Aspects of Ecosystem
• Structural aspects: arrangement s of the elements, types and numbers of
species and their life histories, physical features of the environment
• Functional aspect: flow of energy and cycling of the nutrients
33. Relationships
• In an ecosystem, there exist various relationships between species. The relationship
may be as under:
1. Effects
• Two species may have any of the following kind of effects:
I. They may have a negative effect upon one another (competition).
II. They may have a neutral effect (neutralism).
III. They may have beneficial effect (protoco-operation and mutualism).
2. Other kinds of Relationship
• The species may aggregate, or separate, or show a random relationship to one
another.
36. Divisions of ecosystems from the
energetic perspective
1. Producers
2. Consumers
3. Reducers/decomposers
37. The First and Second Laws
of Thermodynamics
• Thermodynamics is the study of energy and its
transformations.
• First law of thermodynamics: A physical law which states that
energy cannot be created or destroyed, although it can
change from one form to another.
• Second law of thermodynamics: A physical law which states
that when energy is converted from one form to another,
some of it is degraded into heat, a less usable form that
disperses into the environment.
38. Producers, Consumers,
and Decomposers
• The organisms of an ecosystem are divided into three
categories, based on how they obtain nourishment
• Producers
• Consumers
• Primary consumers
• Secondary / tertiary
• Decomposers
39. Food web
• A food web consists of all the food chains in a single
ecosystem. Each living thing in an ecosystem is part
of multiple food chains. Each food chain is one
possible path that energy and nutrients may take as
they move through the ecosystem. All of the
interconnected and overlapping food chains in an
ecosystem make up a food web.
40.
41. Food chain
• A food chain is a linear sequence of links in a food web starting from
"producer" species (such as grass or trees) and ending at apex predator
species (like grizzly bears or killer whales), detrivores (like earthworms or
woodlice), or decomposer species (such as fungi or bacteria). A food chain
also shows how the organisms are related with each other by the food they
eat. Each level of a food chain represents a different trophic level. A food
chain differs from a food web, because the complex network of different
animals' feeding relations are aggregated and the chain only follows a direct,
linear pathway of one animal at a time.
44. Trophic level
• Ecologists group the organisms in a food web into trophic levels. A trophic
level consists of all those organisms in a food web that are the same number
of feeding levels away from the original source of energy (sun).
• First trophic level: Autotrophs (Micro-organisms and all green plants, which make
their own food through the chemical process)
• Second trophic level: Herbivores
• Third trophic level: Carnivores
• Fourth trophic level: Carnivores who depend on the carnivores of 3rd trophic
level.
45. A food chain showing how energy travels through different trophic level
46.
47.
48. Trophic cascade
• An ecological phenomenon triggered by the addition or
removal of top predators and involving reciprocal changes in
the relative populations of predator and prey through a food
chain, which often results in dramatic changes in ecosystem
structure and nutrient cycling. In a three-level food chain, an
increase (or decrease) in carnivores causes a decrease (or
increase) in herbivores and an increase (or decrease) in primary
producers such as plants and phytoplankton.
49. Key concepts
• Keystone species
• Species that have large effect on other
species of the community or the ecosystem
• Ecological services
• Positive benefit that wildlife or ecosystems
provides to people.
