Lec 7- temp constraints Flashcards
limiting factors
environmental conditions that limit the growth, abundance and distribution of organisms
- have physiological stress at niche margins along a limiting factor
optimum range
preferred niche
- middle of bell curve
tolerance range
zone of physiological stress
on L and R side of optimum
- marginal niche
stress
zone of intolerance
unavailable niche
too cold or hot
Law of tolerance
Shelford
- species have optimal survival conditions w/in environmental thresholds
- beyond range, rates of survival decreases - bell-shaped
range of tolerance
species general performance along environmental gradient
1. reproduction in center
2. growth but no repro on L and R of 1
3. survival but no growth on L and R of 2
4. mortality on L and R side of 3
range is up to 3
- fundamental niche, any performance
macroclimate
large-scale climate patterns that prevail over entire regions
- determined by atmospheric cells and topography
microclimate
small-scale, localized climate patterns
- can deviate from macroclimate patterns
- determined by landscape, vegetation or small-scale topography
- not daily
landscape influence microclimate- elevation
- timberline reflects shift in microclimate with increasing elevation
- mean annual temp decreases but trees needs minimum temp for minimum number of days per year to grow
landscape influence microclimate-aspect
N
- slopes exposed to north receive less solar radiation, higher snow loads = more water
- water availability sufficient for a forest to grow
S
- slopes exposed to south receive more solar radiation, lower snow loads = less water
- water availability too low for a forest to grow
- grasses and shrubs prevail
landscape influence microclimate-vegetation
by casting shade- trees and shrubs influence microclimate
- understory- cool temps and evaporation decreases
landscape influence microclimate- surface color
light: reflect light so that surface and surrounding do not increase in temp
dark: absorb light so surface and surroundings increase in temp
albedo
reflectivity of landscape
- how much light is reflected and does not get absorbed
high albedo
- more reflected (80%)
- light coloured
low albedo
- less reflected (10%)
- dark coloured
landscape influence microclimate- boulders and burrows
some adapted to live under rocks or underground in burrows
- burrows and rocks create shade and allow inhabiting animals avoids heat during day so hunt at night
temp in aquatic environments
water temp fluctuate much less than air temp on land
- temp fluctuate b/w -4 to 32
why is water temp stable?
- water has high capacity to absorb heat energy w/o changing temp air
- heat absorbed by water as it evaporates
- water gives up heat energy as it freezes
- physical properties
3000x capacity than air w/o changing temp
why so stable?
more heat you supply the higher the water temp
2 step curve
latent heat of fusion
temp remains constant as solids turning to liquid
latent heat of vaporization
temp remains constant as liquid turns to gas
thawing and vaporization
- energy absorbed as heat is supplied
leads to intermittent, stable temps along a heat gradient
range of tolerance and performance
- temp is limiting factor of photosynthesis
- ## diff plants species show diff range of tolerance and optima in photosynthetic rate along temp gradient
principle of allocation
- amount of energy available to each organism is limited
- when energy is allocated to one fxn, it reduces the energy available for other fxn
- allocation is balancing COSTS vs BENEFITS
- growth, reproduction, activity and maintenance
evolutionary tradeoffs
adapting to one set of environmental conditions generally reduce fitness in other environments
- success in reproduction
death
avoid extreme temp by maximizing repro
- annual plants: survive extreme temp by going to seed
- insects: lay eggs to survive the winter
migration
avoiding extreme temp by migrating to distant regions
- strategy of migration was evolutionary successful b/c advantages of migration outweighed the costs of migrating
acclimatization
acclimation
- physiological and morphological changes in response to changes in environment
- adjustment of lowlanders to high altitudes
diff b/w acclimatization and adaptation
acclimatization: physiological and/or morphological changes in response to changes in environment
- reversable as conditions change
adaptation: evolutionary process that changes anatomy, physiology, behavior on a genetic level
- not reversible
- Tibet
adaptations to extreme temp
- prolonged state of metabolic activity
- hibernation vs estivation
- freeze tolerance and thick fur, fat and short body appendages (polar bear(
heat balance eqn
Hs = Hm+/-Hcd+/-Hcv+/-Hr-He
organisms can either gain or lose body heat through 5 processes
stored, metabolic, conduction, convection, radiation, evaporation
heat balance in plants- cold
adapt to cold temps
- dark colored leaves
- cushion growth forms
- leaf and flower orientation
- smaller surface-area ration
- increase heat gain from Hr and Hcd
- decrease heat loss from Hcv
heat balance in plants-hot
- decrease contact w ground
- open growth form
- reduced leaves
- light surfaces
- increase heat loss from Hcv
- decrease heat gain from Hcd and Hr
Poikilotherms
body temp varies w temp
homeotherms
body temp relatively constant regardless of enviro
ectotherms
control body temp using external energy
- plants, fish, amphibians, reptiles and invertebrates
+/-Hcd+/-Hcv+/-Hr
endotherms
control body temp using internal energy
- use energy from metabolism
Hm
- change rate of metabolism based on the changes in temperature
snakes and lizards
dependent on external sources of heat
diversity of ectotherms and endotherms with cold climate is low
why be endothermic?
cold: shivering generate heat
hot: sweating or panting increases convective cooling
- allows organisms to live in environments in which avg temp lower than their body temp
How does temp regulation work in animals?
continuum
