lecture 7 - temperature constraints and adaptations

what is the difference between macroclimate and microclimate

macroclimate = regional climate patterns

microclimate = local conditions affected by vegetation, aspect, or surface features

how does elevation influence microclimate

temperature decreases with altitude

vegetation transitions (eg. timberline)

mark thermal limits for plant growth

what is aspect and how does it affect temperature

aspect = slope direction

south facing slopes get more sun and are warmer/drier

north facing are cooler and moister

how do vegetation and surface color modify microclimate

Vegetation provides shade and cooling; dark surfaces absorb heat, light surfaces reflect it (albedo effect)

why do water bodies stabilize temperature

water has high heat capacity - absorbs heat when evaporating, relaeses it when freezing - reducing fluctuations

what is range of tolerance

the range of environmental conditions where an organism can survive, grow, and reproduce. outside this, stress or death occurs

how does the range of tolerance relate to the fundamental niche

range of tolerance is for one factor (eg. temperature); fundamental niche includes all abiotic + biotic conditions

what is the law of tolerance

the abundance and distribution of species depend on how close conditions are to their optimum; limiting factors control success

what is the principle of allocation

energy used for one function (growth, reproduction) reduces energy available for others - organisms face trade-offs

write the heat balance equation

Hs = Hm +- Hcd +- Hcv +- Hr - He

Hs = stored heat

Hm = metabolic

Hcd = conduction

Hcv = convection

Hr = radiation

He = evaporation

how do plants adapt to cold

increase heat gain (dark color, orientation), reduce heat loss (compact form, low SA:V), and grow close to ground

how do plants adapt to hot environments

reduce heat gain (light color, reflective hairs), increase convective cooling (open form, elevated leaves)

what is the difference between poikilotherms and homeotherms

Poikilotherms = body temp varies with the environment

Homeotherms = maintain a stable internal temperature

ectotherms vs endotherms

ectotherms = regulate via external heat sources

endotherms = generate heat metabolically

why are ectotherms less diverse in cold regions

low external temperatures limit activity and reproduction; few can thermoregulate behaviorally

how do endotherms regulate temperature

cold - shivering = increase Hm

hot - sweating or panting = increase He

define acclimation and adaptation

acclimation = reversible physiological response within an individual

adaptation = long term genetic change across generations

name 3 strategies to survive extreme temperatures

1. avoidance (migration or dormancy)

2. resistance (fur, fat, freeze tolerance)

3. acclimation

what is freeze avoidance vs freeze tolerance

freeze avoidance = antifreeze glycoproteins prevent ice formation

freeze tolerance = cryoprotectants allow freezing and survival

what are hibernation and estivation

hibernation = cold season dormancy

estivation = heat season dormancy

both reduced metabolism and conserve energy