lecture 07 - resource constraints: temperature Flashcards
what is a macroclimate?
large-scale climate patterns that prevail over entire regions
what is a microclimate
small-scale climate patterns that can deviate from macroclimate patterns
how are microclimates determined
landscape, vegetation or small-scale topography features
how does elevation influence microclimate
elevation can cause different plants to grow
how does aspect influence microclimate
depending on north or south facing, each side may or may not receive as much sunlight as the other
north aspect
slopes exposed to the north receive less solar radiation, higher snow loads, and hence more water. water availability is sufficiently high for a forest to grow
south aspect
slopes exposed to the south receive more solar radiation, lower snow loads, and hence less water. water availability is too low for a forest to grow. grasses and shrubs prevail.
how does vegetation influence microclimate
by casting shade, trees and shrubs. in the understory, temperatures are cooler, and evaporation is decreased
how does surface colour influence microclimate
lighter colours reflect light so that the surface and surroundings do not increase in temperature
darker colours absorb light so that the surface and surroundings increase in temperature
what is albedo?
reflectivity of a landscape = how much light is reflected and does not get absorbed
how do boulders and burrows influence microclimate
some organisms have adapted to live under rocks or underground in burrows. burrows and rocks create shade and allow inhabiting animals to avoid heat during the day
why do water temperatures fluctuate less than air temperatures
larger bodies of water tend to be more stable as it has a higher capacity for absorbing heat energy. heat is absorbed by water as it evaporates.
what is the range of tolerance
the range of an environmental condition in which the organism can live. organisms perform best at an optimum performance range of environmental conditions in the absence of interactions with other species.
why do organisms express physiological stress at the niche margins of a limiting factor
they use more energy to sustain their body and health
law of tolerance
the abundance and distribution of an organism can be determined by the deviation between location conditions and the optimum set of conditions for a species.
what is the range of tolerance in plants
temperature is a limiting factor of photosynthesis in plants
principle of allocation
organisms have limited amounts of energy (how much we can take and how much we can use to keep body alive) when an organism allocates energy to one function, it reduces the energy available to other functions
evolutionary tradeoffs
adapting to one set of environmental conditions generally reduces fitness in other environments
what are the things and organism do when they are at the margins of their tolerance?
die
migrate
acclimate
adaptations to extreme temperatures
allocation using death
avoid extreme temperatures giving all energy to reproduction. organism dies but the offspring have a chance to live
allocation using migration
avoid extreme temperatures by migrating to warmer regions, advantages of migration outweigh the costs of migrating (energy wise)
allocation using acclimation
physiological or morphological changes in an organism in response to changes in the environment. NOT adaptation but the ability to acclimate IS and adaptation (phenotypic plasticity)
define acclimation
physiological or morphological changes in response to changes in the environment within an individuals lifetime. generally reversible as conditions change.
define adaptation
an evolutionary process that changes anatomy, physiology, or behaviour across generations and on a genetic level. NOT reversible.
plant adaptations to cold temps
dark coloured leaves
cushion growth form (closer to ground = more heat)
leaf and flower orientation
smaller surface-area ratio
plat adaptations to hot temps
decrease contact with the ground
open growth form (tall + elongated so more air surrounds them and heat gets taken by the wind)
reduced leaves
light surface
poikilotherms
body temperature varies with environment
homeotherms
body temperature relatively constant regardless of environment
ectotherms
control body heat using EXTERNAL energy
endotherms
control body temperature using INTERNAL energy
why be endothermic?
allows organisms to live in environments in which the average temp is lower than their body temp
