14 Flashcards
Draw and describe a general graph for the performance of species against an environmental gradient
label:
- lethal zones
- where growth occurs
- where reproduction occurs
- where survival occurs
species have ranges of tolerance along environmental gradients
define the ecological niche
- the combination of physiological tolerances and resource requirements of a species
- more casually, a species’ place in the world - what climate it prefers what it eats, etc
draw a graph and describe the Hutchinsonian niche
the niche is an ‘n-dimensional hypervolume’ shaped by the environmental conditions under which a species can ‘exist indefinitely’. Each axis is an ecological factor important to the species being considered
factors determining biomes
- temperature is mostly a function of latitude
- higher latitudes colder; seasonality a function of temperature (summer-winter)
- lower latitudes warmer; seasonality a function of rainfall (dry-wet season)
- rainfall mostly depends on atmospheric circulation, offshore ocean currents, rain shadows
Intertropical convergence
- shows a line of rain clouds across the pacific
- ITCZ shifts seasonally, producing rainy and dry seasons in some parts of the tropics
how does the ITCZ form?
When the northeast trade winds from the Northern Hemisphere and the southeast winds from the Southern Hemisphere come together, it forces the air up into the atmosphere, forming the ITCZ.
Coriolis effect
the earth’s rotation deflects winds: objects (including hurricanes) appear to be deflected eastwards as they move away from the equator and deflected westwards as they move towards the equator
general trends of terrestrial vegetation with climatic variables
- vegetation growth (primary productivity) increases with moisture and temperature
- vegetation stature also increases so region with certain combinations of moisture and temperature develop predictable, characteristic types of vegetation (biomes)
- seasonality is secondarily important
draw a Whittaker’s diagram
—– mostly determines terrestrial biomes
latitude
changes in temperature within basic latitudinal belts
land changes temperature more readily than water; maritime climates are moderate, continental climates are extreme; oceans provide thermal inertia
changes in precipitation within basic latitudinal belts
- evaporation high from warm bodies of water, low from cold
- prevailing winds
- orographic precipitation (air forced up mountainsides undergoes cooling, precipitates on upper windward slopes)
- rain shadows created on leeward slopes of mountain ranges
- seasonality of moisture also important
leeward slope
slopes that are oriented away from the wind
draw diagram of orographic precipitation
latitudinal patterns are complicated by
the distribution of landmasses
how do ocean currents affect precipitation?
driest deserts occur inland of cold-water upwellings as cold water -> dry air
when would animals’ geographical ranges not correspond to biomes (i.e. limited by climate or vegetation)
- transcend biomes (ecological versatility, super generalists)
- not at limits because of recent history (eg limited dispersal)
- limited by other organisms
describe ecological niche modelling
- also called species distribution modelling
- uses data from a species’ present distribution to predict where a species can live
- usually relies on climate data; more rarely on other niche axes, such as resources
what is ecological niche modelling useful for modelling for?
- biological invasions
- how species’ ranges may shift as climate changes
- spread of vector-borne diseases
describe Dengue
a virus vectored by Aedes mosquitoes
observed range shifts
- estimated that species are moving polewards
- although many factors influence a species’ range, there is considerable evidence that numerous species are moving polewards to track recent changes in climate
Scarlet Macaw
temperature (x axis) precipitation (y axis)
