BIOL 208: Lecture 7 - Temperature constraints

Macro Vs. Micro climate definition?

Macro = Large scale climate that prevail over entire regions

Micro = small scale climate patterns (down to cm)

• can deviate from macroclimate patters

What CAUSES macro vs. micro climate?

Macro = Determined by climate CELLS + TOPOGRAPHY

Micro = by landscape, vegetation or small scale topography features

What are some small scale topography features?

Elevation, mountain aspect, vegetation, surface color, depression, ravines etc.

How does ELEVATION influence climate?

Increase in elevation = decrease in mean annual temperature

What reflects a shift in microclimates with increasing elevation?

TIMBERLINE/ tree line

Why is there a timberline with increasing elevation?

Trees need a MINIMUM TEMP (64) for a MIN # of DAYS (94) per year to grow

• Increase in elevation = decrease in mean annual temperature

What is aspect

Direction in which a slope faces

****Specifically in the NORTHERN-HEMISPHERE, how do North and South facing aspects differ?

North facing:

• Receive less radiation = lower temps

South facing:

• Receive more solar radiation

Why do north facing aspects in the N-hemisphere receive less sun?

Tilt of earth

• north aspect = tilted away

****How does North + south aspects differ in landscape in the N-hemisphere? WHY

North = Forest growth

• Less radiation = higher snow load = more water

South = No forest growth

• More radiation = less snow load = less water

What about for the southern hemisphere, how do the aspects differ?

Opposite in the south

• south = less radiation = more water = tree growth

• north = more radiation = less water = no tree growth

How does VEGETATION influence microclimates (2 specific effects on microclimate)

Shade (from trees + shrubs)

In understory:

• Temp = cooler

• Evaporation = decreased

How does surface color influence microclimate?

Lighter colors = reflect sun = no increase in temp

Darker colors = Absorb light = increase in temp

Define ALBEDO

Reflectivity of a landscape

• how much light reflected + does not get absorbed

Contrast between HIGH vs. LOW albedo.

High = reflect more light = light colors

Low = Reflect less light = dark colors

How do Boulders + burrows influence microclimate?

create shade

• allow inhabiting animals to avoid heat during the day

Do water temps fluctuate more or less than air temp?

Less

Why do coastal areas have more mild temp/ How does water maintain a stable temp?

Heat = ABSORBED by water as it EVAPORATES

Heat = EMITTED by water as it FREEZES

• specific heat capacity

Define Range of Tolerance

ENTIRE range of environmental conditions (abiotic factors) in which the organism can survive

****what occurs in the optimal range of conditions?

Grow AND reproduce

• species perform best

What occurs beyond the optimum? What does the organism experience?

survival decreases

• Organism experiences physiological stress at margins of a limiting factor

What zone is beyond the range of tolerance? what occurs there?

Zone of intolerance

• mortality

****How does Range of tolerance differ from Fundamental Niche?

Range of tolerance = in relation to one condition eg. temp (abiotic)

Fundamental niche = all the environmental factors (abiotic + biotic)

Define the Law of Tolerance

The survival and distribution of an organism can be determined by the deviation between location conditions + optimum conditions of the species

• Environmental conditions affect abundance + distribution of organism

Diff plant species show different ranges of tolerance + optima in photosynthetic rate for different climates, Why can’t species have it all and adapt to all different temps?

Evolutionary trade off

Define evolutionary trade off

adapting to one set of environmental conditions reduces fitness in other environments

• adaptations you gain in one environment won’t help you/apply to another

What is the Principle of allocation

Organisms have limited amount of energy

organisms allocate E to one function thus reducing E available to other functions

• Balancing E budget

What do each of the components of the Heat loss equation represent?

Hs = total heat stored

Hm = heat GAINED through metabolism

Hcd = gain/loss Through conduction

Hcv = gain/loss through convection

Hr = heat gain/loss through radiation

He = heat LOSS through evaporation

Define HOW heat is lost for Hcd, Hcv + Hr

Hcd = conduction = in physical contact

Hcv = Convection = through the movement of fluid (water/ wind)

Hr = Radiation = all things release radiating energy regardless of temperature

What variables of the Heat balance equation to do Arctic + alpine plants manipulate to adapt to COLD temperatures?

• Increase heat gain from Hr

• Increase heat gain from Hcd

• Decrease heat loss from Hcv

What 4 adaptions do arctic + alpine plants do to adapt to cold temperatures + which of the heat balance equation variables does it affect.

1. Dark colored leaves = Increase heat from Hr

2. Leaf + Flower orientation = Increase heat from Hr

3. Cushion growth form (low growth form, close too ground) = Increase gain from Hcd + decrease heat loss from Hcv

4. Smaller SA:V ratio = decrease heat loss from Hcv

What is an example of a PLANT that can do thermogenesis? what benefit does it have to the plant?

Skunk Cabbage 

• warmth attracts pollinators

What variables of the Heat balance equation to do Desert plants manipulate to adapt to HOT temperatures?

• Decrease heat gain from Hr

• Decrease heat gain from Hcd

• Increase heat loss from Hcv

What 4 adaptions do desert plants do to adapt to Hot temperatures + which of the heat balance equation variables does it affect.

1. Light colored leaves + reflective surfaces (eg. hairs) = decrease Hr

2. Decreased contact with ground = Decrease heat gain from Hcd + increase heat loss from Hcv

3. Open growth form = Increase heat loss from Hcv

4. Reduce leaves = decrease heat gain from Hr

Why is it always Hr, Hcd + Hcv manipulated for heat balance but never Hm or He?

• Hm is always heat GAIN (always + can never be heat loss)

• He is always heat LOSS (always - can never gain heat from evaporation)

*****What are the 2 classifications of Animals regarding body temp relative to environment?

1. Poikilotherm = body temp VARIES with environment

2. Homeotherms: Body temp = relatively CONSTANT regardless of environmental temp

*****What are the 2 classifications of Animals Based on the organism controls body temp?

1. Ectotherm = control body temp using EXTERNAL energy

2. Endotherms = control body temp using INTERNAL energy

Is the diversity of ectotherms widespread over the globe?

No

• diversity is limited in cold climates due to their reliance on external sources of heat

****What portions of the Heat balance equation do Ectoderms depend on to maintain body temp?

Hr, Hcd + Hcv

****What portions of the Heat balance equation do Endoderm’s depend on to maintain body temp?

Hm

• Use E from METABOLISM

How do endoderm deal with cold? Hot?

Cold: Shivering (contract muscles) = generates heat

Hot: Sweating or Panting = increases CONVECTIVE (Hcv) cooling

Do endoderm’s have a very large range of tolerance for cold temps? What about hot?

Cold temps = yes

Hot temps = no

How does metabolism change with temp?

True or false: in practice organisms form a continuum along the four categories of temp regulation for animals? 

True

***What are the 2 strategies for surviving Extreme temps (at the margins of the range of tolerance)?

1. Avoidance

2. Resistance

****What are the 2 methods for avoiding Extreme temps?

1. Die

2. Migrate

****What are the 2 methods for Resisting Extreme temps?

1. Adaption

2. Acclimate

How does DEATH work to avoid extreme temps?

Funnel all Energy to REPRODUCTION

• adult dies but offspring have a chance

****What are 2 examples of using death to survive extreme temps?

1. Annual plants = SEED before winter

2. Insects = Allocate all resources to offspring which have COLD-TOLERANT life stages

How does migrating help to survive extreme temps?

Costs of staying = greater than costs of migrating to warmer regions

*****What are 3 Categories of ADAPTIONS to extreme weather?

1. Morphological

2. Physiological

3. Behavioral

What are some examples of morphological adaptions to extreme weather

Fur, Fat + feathers

What type of MORPHOLOGICAL adaption are made in terms of appendages. Why?

Short body appendages (eg. ears)

• More volume Less surface area

How do such morphological adaptions help in extreme weather?

• increase insulation

  • Decrease energy lost by Convection (Hcv) or Radiation (Hr)

Hibernation vs. Estivation?

Hibernation = adaptation to COLD temp

Estivation = adaptation to HOT temp

What type of Adaptation to the extremes are hibernation + estivation?

Physiological

What specific physiological adaptation occurs during hibernation/estivation? What occurs in the body?

Prolonged state of REDUCED METABOLIM

Morphological adaptation vs. Physiological adaption. What’s the difference?

Morphological = trait itself (physical structure)

Physiological = seasonal deposition + changes of fur + fat (internal functions)

Freeze avoidance, what CHEMICAL is synthesized in the body during this physiological adaptation?

Antifreeze Glycoproteins

• Manipulate solute concentrations to prevent freezing of cells at cold temps

Freeze Tolerance, what CHEMICAL is synthesized in the body during this physiological adaptation?

Cryoprotectants

• Protect the cells from the freezing that it goes through

*****Freeze tolerance vs. Freeze avoidance. DIFFERENCE in chemical produced, water content in body + rate of activity

Cryoprotectants vs. Antifreeze Proteins:

• Freeze tolerance relies on the presence of cryoprotectants to protect cells from freezing damage,

• Freeze avoidance relies on antifreeze proteins to prevent ice crystals from forming.

Water Content:

• Freeze tolerance often involves dehydration, allowing cells to freeze and thaw without damage,

• Freeze avoidance maintains cell water levels and prevents ice crystal growth.

Metabolic Rate:

• Freeze tolerance slows down metabolic rates to conserve energy = INACTIVE

• Freeze avoidance maintains normal metabolic rates while producing antifreeze molecules (ACTIVE)

What are some examples of Behavioral adaptations to extremes?

Avoidance = seek shelter/ Burrows

Define Acclimation

Physiological changes an organisms goes through in response to changes in the environment

Is acclimation the same as adaptation?

No

Acclimation is a example of what we’ve talked about before in class?

Phenotypic plasticity

*****How can acclimation be considered an adaptation?

The ABILITY TO ACCLIMATE = an adaptation

****Compare the Definitions of Adaptation vs. Acclimation. What is the DIFFERENCE?

Acclimation:

• physiological changes in response to changes in the environment (pH, humidity, temp etc.) Within an individuals life time

• REVERSIBLE CHANGE

Adaptation:

• evolutionary process that changes anatomy, physiology or behavior across generations + on a genetic level

• NOT REVERSIBLE