Ecology is the study of the relationships between organisms and their environment. The biosphere contains all life on Earth, including the interactions between biotic (living) and abiotic (non-living) factors, from individuals to entire ecosystems and biomes. Ecologists use observation, experimentation, and modeling to understand energy flow through trophic levels and the cycling of matter like water, nutrients, carbon, and nitrogen between ecosystems. Population growth rates are influenced by births, deaths, immigration and emigration, and are limited by available resources and carrying capacity.
1. Ecology
• Biosphere – contains combine portions of
the planet in which all life exists; abiotic
and biotic
• Relationships within the biosphere,
ecologists ask questions about events and
organisms that range in complexity from a
single individual to the entire biosphere
• Species – populations – communities –
ecosystem - biome
2. methodologies
• Regardless of the tools they use,
scientists conduct modern ecological
research using 3 basic methods;
• observing, experimenting, modeling
3. Energy Flow
• Sunlight is the main source of energy for
life on earth - photosynthesis
• Some life forms rely on the energy stored
in inorganic chemical compounds (no
carbon) chemosysthesis
• Energy flows through an ecosystem in one
direction, from the sun/inorganic
compounds to autotrophs and
heterotrophs (food chains)
4. Cont.
• Only 10% of the energy available within
one trophic level is transferred to
organisms at the next trophic level
5. Cycles of Matter
• Matter is recycled within and between
ecosystems
• Biogeochemical cycles: matter is not
used up, it is transformed
• Water cycle – evaporation, condensation,
precipitation
• Nutrient cycle – organisms need nutrients
to build tissue and carry out essential life
functions
6. Cont.
• Carbon cycle – key ingredient of living
tissue
• Nitrogen cycle – required to make amino
acids
• Phosphorus cycle – forms DNA and RNA
• Nutrient limitations – scares or cycles
slowly
7. Ecosystems
• Biotic – biological factors
• Abiotic – physical factors
• Both determine the survival and growth of
an organism and the productivity of the
ecosystem in which the organism lives
• Niche – occupation
8. Interaction
• Community interaction, such as, competition,
predation, and various forms of symbiosis can
powerfully affect an ecosystem
• Ecosystems are constantly changing in
response to natural and human disturbances.
• As an ecosystem changes, older inhabitants
gradually die out, new organisms move in,
causing further changes in the community
9. Cont.
• Primary succession – no soil exists
• Secondary succession – changes
existing community without removing soil
• Pioneer species – the first to arrive (other
than soil)
11. Cont.
• Each biome has a characteristic climate
and community of organisms which
include but are not limited to:
• Abiotic factors
• Dominant plants
• Dominant wildlife
• Geographic distribution
12. Aquatic Ecosystems
• Aquatic ecosystems are determined
primarily by the depth, flow, temperature
and chemistry of the overlying water
• Freshwater; divided into two main types;
flowing water and standing water
• Flowing water-river, streams, creeks, and
brooks
• Standing water – lakes and ponds
13. Cont.
• Plankton – tiny free floating organisms
(food)
• Phytoplankton – single celled algae
supported by nutrients in the water and
form the base of aquatic food webs
• Freshwater wetlands – bogs, marshes,
swamps (fresh or salt water)
• Estuaries – rivers meet sea
14. Marine Ecosystems
• Photic – where photosynthesis takes
place, limited to first 200m
• Aphotic – permanently dark, below 200m
• Marine biologist divide the ocean into
zones based on the depth and distance
from shore; intertidal, coastal ocean, open
ocean
15. Cont.
• Intertidal – area where tides changes
• Coastal oceans – low tide mark to
continental shelf (coral reefs)
• Open ocean – edge of continental shelf
outward, largest marine zone, covers 90%
of ocean
• Benthic – sea floor
16. Populations
• Geographic distribution, density, growth
rate
• 3 factors can affect population size; births,
deaths, and immigration/emigration
• Exponential growth – reproduction at a
constant rate
• Under ideal conditions with unlimited
resources, a population will grow
exponentially
17. Cont.
• Logistic growth – when populations
growth slows or stops following a period
of exponential growth
• As resources become less available, the
growth of a population slows or stops
• Carrying capacity – largest number of
individuals that an environment can hold
