BIO 121 MODULE 6 EXTRA LECTURE
NOTES LATEST 2023-2024
Module 6 | Lecture 1: Abiotic limits to distributions and life in the extremes
• Biogeography is the study of the distribution of biodiversity over space and time
• Range maps represent the geographic distribution of species
• Biogeographers try to understand the factors determining a species distribution
• Biotic factors are interactions among living things
• Abiotic factors are interactions between organisms and their non-living physical and
chemical environment e.g., pH, salinity, wind, nutrients
• Some species tolerate a wide range in abiotic conditions, others only tolerate a narrow
amount
• Each species functions best over a limited part of the full range = species optimal range
is called a fundamental niche
• Major abiotic gradients influence species distribution in the terrestrial (temperature,
wind, light, water, nutrients, latitude, elevation, soil type) and aquatic environment
(water currents and temp, nutrients, salinity, pH):
1. Temperature is the most important factor in the distribution of organisms (lower and
upper limits of tolerance):
- Have major effects on biological processes
o Endotherm is an organism that generates/regulates its own internal temp
(humans, mammals, birds)
o Ectotherm is an organism whose body temperature changes with the
environmental temperature. They are located near the coasts (fish, reptiles,
sharks)
- Water temperature drives differences in metabolism, swim speed and diversity in marine
endotherms and ectotherms
- Frost is the most important factor limiting geographic distribution of tropical and
subtropical plants. The Saguaro Cactus distribution in Arizona is surviving based on if
there is frost or not
- Coral reefs present in warm water (20 degree minimum) due to effects of temperature
on coral deposition. Coral-zooxanthellae algae symbiosis is threatened by rising ocean
temperature (algae dissociates with coral at high temperatures causing bleaching
2. Water availability and tolerance:
- Plants have range of tolerance for water (waterlogged to desert conditions).
o E.g., wetlands have zones of vegetation based on amount of time they are
waterlogged (submergent, emergent, wet meadow and upland)
- In terrestrial plants, 3 different photosynthetic pathways exist to fix CO2 (C3 (wheat and
most annual crops), C4 (corn and sugar cane) and CAM (cactus and pineapple))
- C4 and CAM photosynthesis are adaptations to light intensity and water availability
- CAM plants occur in very hot climates – stomata closed during day to prevent water
loss, open a night, so must store CO2 to later run Calvin cycle during daylight
, BIO 121 MODULE 6 EXTRA LECTURE
NOTES LATEST 2023-2024
- 80-90% of all organisms are composed of water
- Animal distribution is intimately linked to water and subsequently distribution (food
source)
3. Light
- In aquatic environments, water absorbs light preventing photosynthesis at depths
greater than about 200 m (euphotic zone)
- Red algae occur at greater depths because they possess accessory pigments enabling
them to use high energy blue light. The pigment is phycoerythrin
4. Wind
- Increases heat and water loss by evaporation/transpiration and convection (wind chill) -
alpine treeline is the tallest a tree will get
- Can intensify oceanic wave action – seaweeds adapted holdfasts, animals with organic
glues and muscular feet
5. Salt Concentrations
- Plant: in arid areas, watering can result in salt accumulation due to evaporation.
Halophytes are plants that tolerate higher salt concentrations – many have salt glands to
excrete salt. Ex) spartina alterniflora (smooth cord grass) found in salt marshes
, BIO 121 MODULE 6 EXTRA LECTURE
NOTES LATEST 2023-2024
- Animals: freshwater fish tend to gain water and have to constantly eliminate water.
Euryhaline marine fish can tolerate wide range of salinity. Salt excreted by gills and
kidneys. Some seabirds and reptiles have specialized salt glands and ducts
6. PH
- normal rainwater pH 5.6
- Slightly acidic due to CO2 forming carbonic acid (H2CO3) when mixed with water H2O +
CO2 = H2CO3 (aq)
- Most plants grow best at pH 6.5 when nutrients are most available – chalk and
limestone soils have a richer flora than acidic soils
- Most fish and aquatic macroinvertebrates favour circumneutral pH 6.5-8.0 - acidity
decreases fish and invertebrate abundance and numbers of species present
• Extremophiles – adapted to and thrive in extremes: temperature, pH, pressure, water
availability, salinity, chemical and radiation. They are useful in biotechnology and
medicine, understanding the origin and evolution of life, potential for life on other
planetary bodies
1. Artemia salina (sea monkey or brine shrimp) living in hypersaline lakes or swamps
NOTES LATEST 2023-2024
Module 6 | Lecture 1: Abiotic limits to distributions and life in the extremes
• Biogeography is the study of the distribution of biodiversity over space and time
• Range maps represent the geographic distribution of species
• Biogeographers try to understand the factors determining a species distribution
• Biotic factors are interactions among living things
• Abiotic factors are interactions between organisms and their non-living physical and
chemical environment e.g., pH, salinity, wind, nutrients
• Some species tolerate a wide range in abiotic conditions, others only tolerate a narrow
amount
• Each species functions best over a limited part of the full range = species optimal range
is called a fundamental niche
• Major abiotic gradients influence species distribution in the terrestrial (temperature,
wind, light, water, nutrients, latitude, elevation, soil type) and aquatic environment
(water currents and temp, nutrients, salinity, pH):
1. Temperature is the most important factor in the distribution of organisms (lower and
upper limits of tolerance):
- Have major effects on biological processes
o Endotherm is an organism that generates/regulates its own internal temp
(humans, mammals, birds)
o Ectotherm is an organism whose body temperature changes with the
environmental temperature. They are located near the coasts (fish, reptiles,
sharks)
- Water temperature drives differences in metabolism, swim speed and diversity in marine
endotherms and ectotherms
- Frost is the most important factor limiting geographic distribution of tropical and
subtropical plants. The Saguaro Cactus distribution in Arizona is surviving based on if
there is frost or not
- Coral reefs present in warm water (20 degree minimum) due to effects of temperature
on coral deposition. Coral-zooxanthellae algae symbiosis is threatened by rising ocean
temperature (algae dissociates with coral at high temperatures causing bleaching
2. Water availability and tolerance:
- Plants have range of tolerance for water (waterlogged to desert conditions).
o E.g., wetlands have zones of vegetation based on amount of time they are
waterlogged (submergent, emergent, wet meadow and upland)
- In terrestrial plants, 3 different photosynthetic pathways exist to fix CO2 (C3 (wheat and
most annual crops), C4 (corn and sugar cane) and CAM (cactus and pineapple))
- C4 and CAM photosynthesis are adaptations to light intensity and water availability
- CAM plants occur in very hot climates – stomata closed during day to prevent water
loss, open a night, so must store CO2 to later run Calvin cycle during daylight
, BIO 121 MODULE 6 EXTRA LECTURE
NOTES LATEST 2023-2024
- 80-90% of all organisms are composed of water
- Animal distribution is intimately linked to water and subsequently distribution (food
source)
3. Light
- In aquatic environments, water absorbs light preventing photosynthesis at depths
greater than about 200 m (euphotic zone)
- Red algae occur at greater depths because they possess accessory pigments enabling
them to use high energy blue light. The pigment is phycoerythrin
4. Wind
- Increases heat and water loss by evaporation/transpiration and convection (wind chill) -
alpine treeline is the tallest a tree will get
- Can intensify oceanic wave action – seaweeds adapted holdfasts, animals with organic
glues and muscular feet
5. Salt Concentrations
- Plant: in arid areas, watering can result in salt accumulation due to evaporation.
Halophytes are plants that tolerate higher salt concentrations – many have salt glands to
excrete salt. Ex) spartina alterniflora (smooth cord grass) found in salt marshes
, BIO 121 MODULE 6 EXTRA LECTURE
NOTES LATEST 2023-2024
- Animals: freshwater fish tend to gain water and have to constantly eliminate water.
Euryhaline marine fish can tolerate wide range of salinity. Salt excreted by gills and
kidneys. Some seabirds and reptiles have specialized salt glands and ducts
6. PH
- normal rainwater pH 5.6
- Slightly acidic due to CO2 forming carbonic acid (H2CO3) when mixed with water H2O +
CO2 = H2CO3 (aq)
- Most plants grow best at pH 6.5 when nutrients are most available – chalk and
limestone soils have a richer flora than acidic soils
- Most fish and aquatic macroinvertebrates favour circumneutral pH 6.5-8.0 - acidity
decreases fish and invertebrate abundance and numbers of species present
• Extremophiles – adapted to and thrive in extremes: temperature, pH, pressure, water
availability, salinity, chemical and radiation. They are useful in biotechnology and
medicine, understanding the origin and evolution of life, potential for life on other
planetary bodies
1. Artemia salina (sea monkey or brine shrimp) living in hypersaline lakes or swamps
