Lecture 1: Physical Environments Flashcards
Define ecology
the scientific study of the interactions that determine the distribution and abundance of organisms
Define distribution
the location in space or the geographic range of a species
Define abundance
the number of individuals and their density in space and time
Define abiotic factors
the non-living components of the environment; the physical and chemical conditions that contribute to the distribution and abundance of organisms
What are 7 examples of abiotic factors?
- TEMPERATURE
- WATER
- nutrient availability
- oxygen availability
- salinity
- pH
- light
Define biotic factors
The living components of the environment that contribute to the distribution and abundance of organisms
What are 5 examples of biotic factors?
- dispersal ability
- behaviour
- predation
- competition
- parasitism and disease
Define habitat
the physical place in which an organism lives
Define niche
the range of abiotic and biotic conditions which an organism can tolerate
T or F: many species can occupy both the same habitat and the same niche
FALSE.
Many organisms can occupy the same habitat, but no two organisms can occupy the same niche. One will become extinct or adapt.
Define organism
the individual that lives within a population. It acquires nutrients and produces wastes and has a boundary that separates internal processes from the environment
the basic unit of natural selection
Define population
a group of individuals from the same species that live and interact in the same area
Define species (in this class)
individuals that are capable of interbreeding and producing fertile, viable offspring
Define community
populations of different species that live and interact in the same area and time
Define ecosystem
one or more communities of living organisms interacting with their nonliving physical and chemical environments
ex. nutrient cycling
Define biome
a geographic region with communities of organisms with similar adaptations
ex. deserts, rainforests
Define biosphere
all the ecosystems on earth
distant ecosystems are linked together by wind and water exchanges and movements of organisms
What is the hierarchy of ecological systems?
organism < population < community < ecosystem < biome < biosphere
What is the key field of research involved in studying organisms? Describe it
Individual approach
looks at the connection between physiology, behaviour and an organism’s environment
tends to focus on adaptations
What is the key field of research involved in studying populations? Describe it
Population approach
studies the variations in the abundance, density and composition (genetic, sex ratio, age) of groups of individuals over space and time
What is the key field of research involved in studying communities? Describe it
Community approach
studies how interactions between species promotes or limits their coexistence
What is the key field of research involved in studying ecosystems? Describe it
Ecosystem approach
studies the flow of energy and cycling of matter (ex. carbon, nitrogen, and phosphorous) between physical and biological components
What is the key field of research involved in studying the biosphere? Describe it
Biosphere approach
studies the movements of air and water across Earth’s surface and how it impacts all other levels of the hierarchy
What are the three key thermal properties of water?
- resistance to temperature change
- resistance to phase changes
- density is affected by temperature
Describe why water is able to resist changes in temperature
water has a very high specific heat capacity which means it requires a lot of energy to raise the temperature even by 1 degree C. This is due to the hydrogen bonds that form water molecules. They require a lot of energy to break and reform.
Describe why water is able to resist phase changes (liquid, solid, gaseous)
water molecules are made up of hydrogen bonds between the partially negative oxygen molecule and 2 partially positive hydrogen molecules so it is very polar. This means the bonds require a lot of energy to break
Describe how the density of water changes with temperature
Water is less dense as a solid than it is as a liquid
Density of water is highest at 4 degrees C
higher temperatures = less dense because the molecules are moving faster so the H-bonds break and reform at a faster rate
lower temperatures = less dense because the molecules are moving slower and stretch out around the H-bonds to form a crystal lattice and prevent the bonds from breaking and reforming
Explain how the density of water results in a favourable environment for life but also limits the form and function of life
For example, in the Arctic, the solid water (ice) is less dense than the liquid water, so it will float. The floating ice results in a terrestrial environment for Arctic animals like polar bears. The ice also acts as an insulator for the body of water underneath so that an aquatic habitat can be maintained year round in a stable temperature.
Limits organisms’ ability to move through the water column - ability is dependent on their body density in relation to the density of water
- many aquatic organisms can adjust their density to maintain position or move through the water column
Explain how the viscosity of water results in a favourable environment for life but also limits the form and function of life
viscosity of water creates friction while an organism moves through the water column and makes it so that movement requires much more energy and is much slower
organisms have to compensate for this by having streamlined body shapes to reduce drag and methods to do gas exchange like countercurrent gas exchange.
Explain the importance of hydrogen ions in water
H+ ions are extremely reactive and can dissolve minerals from rocks and soils which is crucial for releasing otherwise trapped minerals required by organisms
What pH range is acidic, neutral, and basic
<7 = acidic 7 = neutral >7 = basic
What 3 elements do organisms require in the greatest quantities?
hydrogen
oxygen
carbon
What are the other 8 elements organisms also require?
- nitrogen
- phosphorous
- calcium
- iron
- magnesium
- sulfur
- potassium
- sodium
How does the particulate composition of soil affect its ability to provide dissolved nutrients and oxygen to plants?
Nutrients in the soil are usually in dissolved in an aqueous solution and the composition of the soil particles determines how well the soil can retain or drain water and the dissolved nutrients.
Soils with larger particulates like sand will drain more quickly and lose nutrients easier but will have more air space and more available oxygen
Soils with smaller particulates like clay will drain slower and hold onto nutrients easier, but will have less air space and less available oxygen
What is the best soil type for plant productivity?
Loam: a combination of 40-50% sand, 30-40% silt, and 20% clay
Why can oxygen availability be an issue in aquatic environments?
The dissolved oxygen content is much lower in water than it is in the air - 1% to 21% in air
Oxygen also diffuses much slower in water due to the viscosity and density of water so it requires more energy for oxygen to move from water into the systems of aquatic organisms
How is oxygen availability in aquatic environments affected by temperature?
dissolved oxygen content is INVERSELY related to temperature
As temperature increases, dissolved oxygen content will decrease
ex. tide pools experience this dramatically
Describe some adaptations in plants that help them overcome the low oxygen content of aquatic environments?
- aerenchyma: many root cells die and form air filled tubes that are better suited for oxygen transport
- pneumatophore: above ground extensions of root tissues filled with aerenchyma that enhance the ability of plants in swampy soils to access air
- adventitious roots: roots that grow above the surface of the soil to take advantage of the oxygen content in the air
Describe some adaptations in animals that help them overcome the low oxygen content of aquatic environments?
Countercurrent gas exchange: maximizes oxygen uptake by having blood flow in opposite directions
Keeps oxygen constantly moving from water into the blood stream and from CO2 in the blood back into water
Why is CO2 usually less available to plants in aquatic environments than in terrestrial environments?
CO2 is a large molecule so diffusion into aquatic plants is a very slow and energetically intensive process
aquatic organisms also are surrounded by a boundary layer which slows down diffusion of large molecules even more
What is the primary source of carbon in aquatic environments?
Bicarbonate (HCO3)
An even larger molecule than CO2
Describe osmoregulatory issues experienced by aquatic organisms in saltwater conditions and provide examples of adaptations to overcome these challenges
there is a lower salt concentration in the organism than in its surroundings so water will move out of the organism by osmosis (water moves from low solute concentration to high)
Adaptation: balance the loss by drinking saltwater and producing very concentrated urine with little water
Solutes will diffuse into the fish due to the concentration gradient (solutes move from high to low)
Adaptation: solutes diffuse across skin, lungs, and gills
Describe examples of adaptations in plants that allow them to survive in hot environments
In hot temperatures, plants are vulnerable to desiccation
they will close their stomata when soil dries up
stomatal pits: the air in the pits can be kept moist due to trichome hairs to prevent water loss and allow stomata to remain open
trichome hairs: reflect direct sunlight from plant surface and trap moisture
reduced surface area of leaves and photosynthesis instead occurs in the chloroplast containing cells of the stem
Describe examples of adaptations in plants that allow them to survive in cold environments
- seasonally drop leaves to reduce vulnerable tissue
- concentrate organic compounds in tissues to lower freezing temperature
- produce antifreeze proteins to prevent ice crystal formation in cells
What are some examples of how marine organisms excrete salt?
Animals have specialized salt glands
- ex. marine Iguanas
plants: take in saltwater and concentrate organic molecules in their roots to create higher solute solution in the tissues compared to the salt water so that water will flow from their surroundings into their roots
Describe examples of adaptations in animals that allow them to survive in hot environments
temperate animals have veins in the extremities that are farther apart and closer to the surface
as blood travels out to extremities, it cools and as it returns to torso, it is much cooler than it was going out
Describe examples of adaptations in animals that allow them to survive in cold environments
SOME animals (like frogs) can: - concentrate organic compounds in tissues to lower freezing temperature
- produce antifreeze proteins to prevent ice crystal formation in cells
Others:
- countercurrent heat exchange: veins are arranged close together and close to arteries (away from surface) in extremities (limbs) to reduce heat loss to surroundings
- fur, fat, feathers reduce heat loss
- thermal inertia: resistance to temperature change with large body volume - increased surface area to volume ratio = helps with insulation
Describe examples of adaptations in animals that allow them to survive in variable environments
Seasonal fluctuations can be a real issue for aquatic animals life fish so they can acclimate to gradual changes in temperature by using different enzymes that function better in different temperatures
Describe ectotherms and give an example
animals with an internal body temperature that matches the external environment and will fluctuate as the environment fluctuates
ex. reptiles
Describe endotherms and give an example
animals with an internal body temperature that is constant and maintained at a different temperature than the external environment
ex. mammals
Describe the photosynthetically active region of the electromagnetic spectrum
the visible light part of the electromagnetic spectrum that is used by photosynthetic organisms (400nm-700nm)
What factors impact the availability of visible light to plants in terrestrial environments?
shading by other plants reduces light availability under forest canopies
Canopies have the most light but as you move down through the plant growth levels, less and less light will filter through until there’s mostly shade on the forest floor
What factors impact the availability of visible light to photosynthetic organisms in aquatic environments?
Most light reflects directly off the water surface so there’s already not much light actually penetrating into the photic zone
Then most of the light that does penetrate into the photic zone is absorbed by photosynthetic organisms and other particles in the water, so less light will be able to penetrate deeper
Which colours of light are most important in providing energy for photosynthesis of terrestrial plants?
Chlorophyll a (major pigment): absorbs blue and red wavelengths
chlorophyll b: absorbs blue and orange wavelengths
carotenoids: absorb more blue-green and yellow
In water, which colour (and wavelength) penetrate the deepest? Why?
Blue because light quality changes with depth and not all pigments are absorbed in the same amount as you move down the water column
this is also due to the fact that not much light penetrates deeper than 200m
What is homeothermy?
temperature regulation that endotherms use via a negative feedback loop
Describe dispersal ability and how it’s a biotic factor
characteristics of a species itself that limit its dispersal
ex. an animal that can walk, run, swim, or fly better than others will be able to disperse further
ex. a tree that has a better ability to more widely disperse seeds
Describe how behaviour can be a biotic factor
animals can look for specific cues in habitats when selecting where to be
How do hummingbirds regulate their temperature?
by increasing metabolic rate
lower air temperature = higher metabolic rate, especially when active
as air temp. increases, their metabolism can drop because they won’t need to consume as much oxygen to maintain their internal temperature
torpid: temporary hibernation state done at night to slow down metabolism
List 2 advantages and 2 disadvantages of ectothermy
ADV:
- lower metabolic requirements allow organisms to live where food or oxygen is less available
- can withstand more environmental fluctuations
DIS:
- do not do as well in extreme temperatures
- there is an upper limit on body size due to efficiency of heat exchange so they tend to be smaller organisms
List 2 advantages and 2 disadvantages of endothermy
ADV:
- less effected by external temperatures so metabolic rates can be increased to maintain internal temperature
- can survive and reproduce in much more extreme climates
DIS:
- very energetically expensive to maintain a constant internal temperature = requires much more food and oxygen
- there is a lower limit on body size due to the surface area: volume ratio = larger organisms don’t tend to lose heat as quickly as smaller organisms
T or F: light is the primary source of energy for the biosphere - why/why not?
TRUE because of photosynthesis
Describe the photic zone of aquatic environments
the top 200m of the water column where light penetrates
the zone where photosynthetic organisms occupy
