Green Generation
Part I : General Ecological Principles
BMMS
Science Olympiad
2014 - 2015
Part I: Review of General Ecology
ECOLOGY – how organisms interact with one another
and with their environment
ENVIRONMENT – living and non-living components
• ABIOTIC – non-living component or physical factors
as soil, rainfall, sunlight, temperatures
• BIOTIC – living component are other organisms.
ECOLOGICAL ORGANIZATION
• INDIVIDUAL – individual organisms
• POPULATION – organisms of same species in
same area (biotic factors)
• COMMUNITY – several populations in same
area (biotic factors)
• ECOSYSTEM – community plus abiotic factors
• BIOME – group of ecosystems with the same
climate and similar communities (e.g. desert
biome)
• BIOSPHERE – all ecosystems on earth
ECOLOGICAL ORGANIZATION
ECOLOGY OF INDIVIDUALS
• Homeostasis – property in which variables are
regulated so that internal conditions remain stable
and relatively constant. It is a process that maintains
stability of an individual’s internal environment in
response to changes in external conditions.
(Warm-blooded vs Cold-blooded)
• Components
– Physiological Ecology (Physiology is the way in
which living organism or bodily part functions)
– Temperature and Water Balance
– Light and Biological Cycles (internal biological
clock, called the circadian rhythm, to help adapt
to daily cycle of day and night)
– Physiological Ecology and Conservation
ECOLOGY OF POPULATIONS
• Population ecology - The study of populations in
relation to the environment, including
environmental influences on population density
and distribution, age structure, and variations in
population size.
• Properties of populations
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Patterns of distribution and density
Intraspecific competition
Population dynamics
Growth and regulation
• Altering population growth
• Human impact
Population Size, Distribution and Density
• Population size is the number of individuals in a
population. Knowing the size can explain whether the
species is doing well or not. Example: Endangered
species have very small population size.
• Population distribution describe how individuals are
spread throughout their habitat. Sparsely populated
areas contain few animals. Densely populated areas
contain many animals. Sparsely populated places tend
to be difficult places to live (lack of food and water,
challenging climate) like Antartica or Mojave Desert.
• Population density is a measurement of the number of
individuals in an area. Population density is calculated
by dividing the number of individuals by area.
Intraspecific vs Interspecific
Competition
• Interspecific competition is the competition
for resources between individuals of different
species.
• In intraspecific competition, members of the
same species may compete for food, shelter,
water, and mates.
Growth Curves
(a)
Applies to populations with
no growth limits
(b) Growth that tops out at a certain carrying
capacity because of limited resources
Survival Curves
Survivorship is the percentage of
remaining survivors of a population
over time; usually shown
graphically.
Type I survivorship curve: most
individuals live out their life span
and die of old age (e.g., humans).
Type II survivorship curve:
individuals die at a constant rate
(e.g., birds, rodents, and perennial
plants).
Type III survivorship curve: most
individuals die early in life (e.g.,
fishes, invertebrates, and plants).
Survivorship Curves
Example of
Type I : Humans
and large
mammals
Example of
Type II : Birds and
lizards
Example of
Type III : Fish and
Frogs
ECOLOGY OF COMMUNITIES
• Closed vs. Open communities
– Closed – sharp boundaries
– Open – Lack boundaries
• Species abundance and diversity
– Keystone species are those whose presence or absence profoundly
affects other species in the community. Example: Gray wolf in
Yellowstone National Park were hunted / poisoned to protect elks &
bison. No wolves remaining in Yellowstone by 1924. With their
primary predator eliminated, elk populations exploded, leading to
overgrazing of plants. Significant declines in the populations of plants
influenced other wildlife, such as beaver and songbird populations.
Disappearance of these plant species not only caused loss of habitat
for other animals but also influenced other ecological factors,
including water temperature regulation via shading & nutrient cycling.
Removal of wolves thus led to instability of the environment.
• Trophic Structure of Communities
– Food chains
– Food web : graphical depiction of the interconnections among species
based on feeding relationships
– Trophic pyramid
INTERACTIONS AMONG SPECIES
• Interactions
• Interspecific competition
• Predation
• Exploitation
• Symbiosis
Types of Species Interactions
• Mutualism – both benefit. Ex: Oxpecker (a kind of bird)
and the rhinoceros or zebra. Oxpeckers land on rhinos or
zebras and eat ticks and other parasites that live on their
skin. The oxpeckers get food and the
rhinos / zebra get pest control.
• Commensalism – one benefits, other neutral. Ex:
Barnacles and whales. Barnacles benefit by receiving
transportation all over the ocean, which exposes them to
more currents and feeding
opportunities. The whale neither
benefits nor is harmed.
Types of Species Interactions
• Neutral – two species do not interact
• Parasitism – one benefits, one (host) harmed
but not killed. Ex: Tapeworm, Mosquito
• Predation – one benefits, other killed
Predator - Prey Relationship
Food Chain
• A simple pathway of the flow of nutrients in an ecosystem is
called a food chain. It is called a 'chain' because each living
organism provides a link in the chain and each organism
depends on the organism that comes before it.
• rose plant → aphids → beetle → chameleon → hawk
• Producer (Autotroph)
• Consumers (Heterotrophs)
1st order Consumer or Herbivore
2nd order Consumer or 1st order Carnivore
3rd order Consumer or 2nd order Carnivore
4th order Consumer or 3rd order Carnivore
Consumers that are able to eat both plants and animals are
known as omnivores
– animals that eat only dead animals are called scavengers
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• Decomposers – consume dead and decaying matter.
– Example: Bacteria & Fungi
Food Web
Each organism living in an ecosystem may have various food sources. Each
organism interacts with others and if one of the organisms is removed, all other
organisms are affected and the food web becomes unbalanced. Food webs also
become unbalanced if a new organism is introduced
ECOLOGY OF ECOSYSTEMS
• Energy Flow
– Energy Flow Pyramids
– Bio-mass Pyramids
• Community Succession and Stability
• Nutrient Recycling – nutrient cycles
• Decomposition and nutrient cycling are
fundamental to ecosystem biomass
production.
Energy vs Nutrient
• Nutrients – cyclic
(Biogeochemical
Cycles)
• Energy flow – one
way
Ecologic Pyramids
Ecological pyramid - a graph representing trophic
level numbers within an ecosystem. The primary
producer level is at the base of the pyramid with
the consumer levels above.
Numbers pyramid - compares the number of
individuals in each trophic level.
Biomass pyramid - compares the total dry weight
of the organisms in each trophic level.
Energy pyramid - compares the total amount of
energy available in each trophic level. This energy
is usually measured in kilocalories.
Numbers Pyramid
Biomass & Energy Flow Pyramids
In any food web, the energy that is trapped by the producers is passed
on to the consumers. Not all the energy, however, is passed on. Some of
the energy is lost to the environment as heat, sound and kinetic energy.
By the time the energy reaches the top of the food web, only a little of
the original energy remains. There is less food energy at each trophic
level and therefore there are fewer types of each organism.
Hydrologic (Water) Cycle
Phosphorus Cycle
Phosphorus Cycle
• Unlike many other biogeochemical cycles, the
atmosphere does not play a significant role in the
movement of phosphorus, because phosphorus and
phosphorus-based compounds are usually solids at
the typical ranges of temperature and pressure found
on Earth.
• Phosphorus is an essential nutrient for plants and
animals.
• Of all the elements recycled in the biosphere,
phosphorus is the scarcest and therefore the one
most limiting in any given ecological system. It is
indispensable to life, being intimately involved in
energy transfer and DNA of all cells.
Phosphorus Cycle
• Much of the phosphorus on Earth is tied up in rock
and sedimentary deposits, from which it is released
by weathering, leaching, and mining.
• Read more about Phosphorus Cycle:
http://en.wikipedia.org/wiki/Phosphorus_cycle
http://www.britannica.com/EBchecked/topic/457621/
phosphorus-cycle
Nitrogen
• Nitrogen is abundant in Earth’s atmosphere (78% of the air
we breathe is Nitrogen) but atmospheric nitrogen has limited
biological use, leading to a scarcity of usable nitrogen in the
ecosystem.
• Nitrogen must be released into the environment in usable
form to be consumed.
• Nitrogen molecule is held together by 3 covalent bonds,
making it difficult to break them apart.
• Read more about Nitrogen Cycle:
http://en.wikipedia.org/wiki/Nitrogen_cycle
http://www.nature.com/scitable/knowledge/library/the-nitrog
en-cycle-processes-players-and-human-15644632
Nitrogen Cycle
• Why is Nitrogen cycle important ?
The nitrogen cycle is important due to its role as a
basis for production of nitrogen that is essential to
all forms of life. Nitrogen is an important
component of complex molecules such as amino
acids and nucleotides, which lead to the creation
of proteins and DNA, the building blocks of all life.
Plants absorb nitrogen in the form of ammonium
and nitrate ion. Animals receive nitrogen from
feeding on living or dead organic matter.
Nitrogen Cycle
Nitrogen Cycle
Carbon Cycle
Carbon Cycle
• Carbon cycle is the process in which carbon
atoms are recycled over and over again on Earth.
• The complete cycle is made up of "sources" that
put carbon back into the environment and
"sinks" that absorb and store carbon.
• Carbon is known to be a basic building block of
life: carbohydrates, proteins, lipids, and nucleic
acids
Carbon Cycle
• Since all living things contain the element
carbon, it is one of the most abundant
elements on Earth. The total amount of
carbon on Earth, always remains the same,
although the carbon regularly changes its
form.
• Read more about Carbon Cycle:
http://www.encyclopedia.com/topic/carbon_cycle.aspx
http://en.wikipedia.org/wiki/Carbon_cycle