Ecology
March 6, 2021
1 Species, communities, ecosystems
• Species: group of organisms in an ecosystem that inbreed and pro-
duce fertile offspring
– similar physical characteristics
– common gene pool
– common phylogeny (family tree)
Exception:
• species that reproduce asexually (not interbreeding)
• infertile individuals
• Hybrids: different species interbreeding (closely related)
Example: horse + donkey = mule
Horse + zebra = zorse
tiger + lion = liger
Organism’s division based on food sources / modes of nutrition:
• Autotrophs: synthesize organic molecules from inorganic molecules
(photosynthesis)
also called PRODUCERS (plants, algae, bacteria)
• Heterotrophs: obtain organic molecules from other organisms (her-
bivores or carnivores)
also called CONSUMERS (Animals, fungi, bacteria)
DECOMPOSERS: consume non-living matter (recycle dead organic mat-
ter, returns to food chain)
1
, • Detrivores: internally digest (example: insects)
• Saprotrophs: externally digest (example: fungi)
Cycle:Producers transform inorganic matter in organic compounds. Con-
sumers transform organic compounds in organic monomers. When con-
sumers die and are digested by decomposers the matter goes back to soil.
Life organization:
1) individual: one organism
2) Population: more individuals of one species living together
3) Community: more populations living in the same place
4) Ecosystem: Biotic (living: animals, plants, ...) and Abiotic (non living:
light, soil, ...) factors within a system
5) Biome: collection of vegetation and wild life and climate in a geograph-
ical area
6) Biosphere: combination of all ecosystems in a planet (Earth)
2 Energy flow
Light →Plant →Herbivore →Carnivore
• Food chain: sequence showing feeding relationships and energy flow
(arrows follow energy flow)
• Trophic level: how many organisms has energy flowed through
Example:
Food chain: Maize → locust → lizard → snake
Levels: primary producer → primary consumer → secondary consumer →
tertiary consumer
At every level 10% energy is passed to the next energy, 90% energy is
lost (at most 4 levels, then no more energy is available to sustain a new
level)
primary producer (100) → primary consumer (10) → secondary consumer
(1) ...
2
March 6, 2021
1 Species, communities, ecosystems
• Species: group of organisms in an ecosystem that inbreed and pro-
duce fertile offspring
– similar physical characteristics
– common gene pool
– common phylogeny (family tree)
Exception:
• species that reproduce asexually (not interbreeding)
• infertile individuals
• Hybrids: different species interbreeding (closely related)
Example: horse + donkey = mule
Horse + zebra = zorse
tiger + lion = liger
Organism’s division based on food sources / modes of nutrition:
• Autotrophs: synthesize organic molecules from inorganic molecules
(photosynthesis)
also called PRODUCERS (plants, algae, bacteria)
• Heterotrophs: obtain organic molecules from other organisms (her-
bivores or carnivores)
also called CONSUMERS (Animals, fungi, bacteria)
DECOMPOSERS: consume non-living matter (recycle dead organic mat-
ter, returns to food chain)
1
, • Detrivores: internally digest (example: insects)
• Saprotrophs: externally digest (example: fungi)
Cycle:Producers transform inorganic matter in organic compounds. Con-
sumers transform organic compounds in organic monomers. When con-
sumers die and are digested by decomposers the matter goes back to soil.
Life organization:
1) individual: one organism
2) Population: more individuals of one species living together
3) Community: more populations living in the same place
4) Ecosystem: Biotic (living: animals, plants, ...) and Abiotic (non living:
light, soil, ...) factors within a system
5) Biome: collection of vegetation and wild life and climate in a geograph-
ical area
6) Biosphere: combination of all ecosystems in a planet (Earth)
2 Energy flow
Light →Plant →Herbivore →Carnivore
• Food chain: sequence showing feeding relationships and energy flow
(arrows follow energy flow)
• Trophic level: how many organisms has energy flowed through
Example:
Food chain: Maize → locust → lizard → snake
Levels: primary producer → primary consumer → secondary consumer →
tertiary consumer
At every level 10% energy is passed to the next energy, 90% energy is
lost (at most 4 levels, then no more energy is available to sustain a new
level)
primary producer (100) → primary consumer (10) → secondary consumer
(1) ...
2
