Lecture 2: Climate and other niches Flashcards
What is plotted on the y-axis and x-axis on the gradients
y-axis: Performance of the species
x-axis: Environmental gradients
the x-axis could only be a continuous factor like salinity, ph, temp etc
What was the problem with the gradient diagram?
Only one environmental factor could have been plotted, either temp, ph, salinity or resource like density of the prey etc. Moreover, more than 2 environmental conditions affect the species, hence needed something that has more than one gradient.
What is ecological niche?
It is the combination of physiological tolerance and the resource requirements of a species.
or casually a species place in the world, where it lives, what it eats.
What is the ‘Hutchinsonian niche’? (Year 1957)
It was made by G.Eveleyn Hutchinson. Same person who wrote the book ‘ The ecological theater and the evolutionary play’
He suggested that species have niches and made a mathematical expression.
How did G. Evelyn Hutchkinson describe the ecological niche?
He described niche as an ‘n-dimensional hyperbole’ in which each axis is an ecological factor important to specie being considered.
What is shown in the ellipses in the Hutchkinsonian niche?
It is the range of values of environmental conditions 1 and 2 where the species can survive.
Describe the colours in the ‘hutchkinson’s niche’
The white zones are the lethal zones where the specie in study is being considered.
The dark blue: They are the optimal conditions under which the species grow the best for that specie.
What is the most important factor for all species on earth?
Temperature, hence always ask where the species live, like in what climate they can tolerate in order to know more about them.
What was the x and y axis for the scarlet macaw’s two dimentional niche.
-x: temp in C
-y: precipitation in mm
Usually lived in warm climate
Why have n-dimentions?
The survival of the specie depends on more than two environmental conditions, hence having only two gradients would be incomplete model. So you need n-dimensions to be accurate.
What is temperature a function of?
The function of latitudes
-warmer at the equator and cooler towards the poles.
What drives the seasonal patterns in temp in the temperate zones?
The temperature, they have warmer summers and cooler winters.
How’s temp at the equator:
Much more constant, and seasonality is a function of rainfall. That’s why the tropical forests have rainy and dry temp.
What affects rainfall?
Atmospheric circulation, off-shore currents and rain shadows (created by mountains)
What is a biome and what determines it?
Biome: All species, vegetation in an area (is what species live there, they type of vegetations that grows etc)
What determines it: Temperature, Rain fall and their seasonality
Why is it warm at the equator?
Sun shines directly at the equator (higher angle is concentrated at a small area)
Ie: the incoming photon vector hits the earths surface perpendicularly, which increases the photon density, making it warm at the equator.
Why is it cold at the poles?
The incoming photon vector, hits the earth at a lower angle, which covers more area, hence photon density becomes less making it cooler.
What does tilt generate?
Seasonality and Temperature
How do you know its winter at poles?
- The tilt in the earth away from the earth cause even larger angle, making it cooler, and eath heats up less.
What is seasonality a function of at the tropics?
Function of rainfall, hence tropics have dry or wet climate
What is seasonality a function of at the temperate regions?
Function of temperature. (Warmer summers and colder winters)
Why are hadley cells created in the first place?
Sunlight hits directly, warming the earth a lot at the equator; the hot air masses rise at the equator and drift north and south.
Since they can’t keep going forever, they go 30 deg north and 30 deg south and fall back into the earth.
What is the Adiabatic lapse rate?
Rate at which the air cools down, As the hot air raises from the hadley cells, the air cools down 5-10 degrees celsius per KM.
This can be seen when climbing up the mountains.
Why is it rainy at the equator?
As the air cools at the adiabatic lapse rate, the water vapor condenses and falls as rainfall, making it so rainy.
What happens to air masses after the rain fall at the equator?
They become dry masses and fall back to the earth 30 degrees north and south. They get stripped out of all the moisture and with high pressure.
Why are desserts located at 30 degrees north and south?
Because the air masses from the hadley cells have been stripped out of all moisture and water vapour after the rainfall, and are now dry with high pressure. They fall back to the earth at 30 degrees north and south of latitudes making that region dry hence deserts.
