Download PopulationsPP

Geochemical Cycles , Symbiosis,
& Population Growth
Biogeochemical Cycles of matter
•
Unlike energy, matter is constantly being recycled
in an ecosystem in what are known as
biogeochemical cycles.
• Water Cycle: continuous flow of water on Earth:
- Precipitation – rain, snow, sleet, hail
- Evaporation – change of state from liquid to gas
- Condensation – change of
state from gas to liquid
- Transpiration – evaporation
of water from plant leaves
- Respiration – release of water
from animal breathing
Carbon – Oxygen Cycle
The continuous flow of O2 & CO2 on Earth
• Biological processes (photosynthesis, respiration, &
decomposition)
• Geochemical processes (volcanoes)
• Human activity (burning of fossil fuels & deforestation)
Nitrogen Cycle: continuous flow of N on Earth.
• Nitrogen fixation, denitrification, & human activities
contribute
• N is the most abundant gas in atmosphere (78%)
• Nitrogen gas is unusable for plants,
it must be “fixed” or
changed into the nitrate
or nitrite form by bacteria
in the soil. Known as
nitrogen fixation
Phosphorus Cycle
• The continuous flow of phosphorus from land to water
to organisms and back to land,
• P is important in the production of DNA and RNA.
• phosphorus is
NOT found in
the atmosphere.
Found in rocks
and minerals.
Symbiosis: Relationship between 2 species
that benefits at least one of the species.
• Mutualism – both organisms benefit. ex: lichens (fungus
& algae); and bees pollinate flowers
• Commensalism – one benefits; the
other is neither helped nor harmed.
ex: bird nest in a tree, clownfish in anemone
• Parasitism – one benefits; the other
is harmed. ex. fleas & ticks on a dog
3 characteristics of a population: Growth Rate,
Population Density, & Geographic Distribution
1. Geographic Distribution
• Clumped Dispertion – far apart in some areas, close
together in some areas.
• Uniform Dispertion – evenly spread out
• Random Dispersion – no pattern
2. Population Density:
the number of individuals per unit area
Methods of conducting a population survey:
Direct observation, indirect observation, sampling,
& catch and release.
3. Growth Rate (includes immigration & emigration):
the difference between birth and
death rate of a population.
• Immigration – movement of individuals of a
population moving into an area. (I = in)
• Emigration – movement of individuals of a
population out of an area. (E = exit)
- Logistical Growth: population growth slows or
stops as resources become less available;
resulting in an S-shaped curve.
- Exponential Growth: population increases
rapidly in a few generations under ideal conditions
in which birth rates exceed death rates.
- Carrying Capacity: largest population an
environment can support.
Limiting Factors to Population Growth:
• Density Dependent: Competition, predation,
parasites, & disease.
-Competition: the struggle among organisms for
basic needs (food, water, shelter, space, mates)
-Predation: Predator-Prey Relationships.
• Density Independent:
weather conditions,
natural disasters,
seasonal cycles, &
human activities.