homeostasis in animals temperature. how do physiological adaptations alter the organism’s...

Homeostasis in AnimalsHomeostasis in AnimalsTemperatureTemperature

How Do Physiological Adaptations How Do Physiological Adaptations Alter the Organism’s Tolerance Alter the Organism’s Tolerance

Limits? Limits? Species’ tolerance Species’ tolerance limit is determined by limit is determined by its biochemical, its biochemical, physiological, and physiological, and morphological morphological characteristics.characteristics.

Environmental Environmental changes may cause changes may cause detrimental impacts detrimental impacts on the organism’s on the organism’s internal conditions if internal conditions if they exceed the they exceed the tolerance limits.tolerance limits.

Two possibilities for physiological adaptations:•Tolerance to a wide range of internal conditions•Mechanisms that counteract the external challenge so that internal homeostasis is maintained (often comes at a energetic cost)

Ecology: Evolution, Application, Integration David T. Krohne Copyright © 2015 Oxford University PressEcology: Evolution, Application, Integration David T. Krohne Copyright © 2015 Oxford University Press

Temperature and Water Availability Are Temperature and Water Availability Are Universally ImportantUniversally Important

TemperatureTemperatureDirectly affects the Directly affects the rates of all physiological rates of all physiological and biochemical and biochemical reactionsreactionsAffects conformation of Affects conformation of biological moleculesbiological molecules

WaterWaterThe basis of lifeThe basis of lifeAll biochemical All biochemical reactions occur in reactions occur in aqueous phaseaqueous phaseOptimal cellular water Optimal cellular water and solute and solute concentrations are concentrations are maintained within maintained within narrow limitsnarrow limits

Will be used to illustrate the fundamental principles of adaptations


Temperature AdaptationsTemperature AdaptationsWhat are the main selective pressures and respective What are the main selective pressures and respective

adaptations?adaptations?

High temperatureHigh temperatureDenaturation of Denaturation of proteins and DNAproteins and DNA

Heat shock proteins Heat shock proteins (HSPs)(HSPs)

Expression of more Expression of more heat-stable proteinsheat-stable proteins

Increase in G-C Increase in G-C content of DNAcontent of DNA

Low temperatureLow temperatureFreezing of Freezing of intracellular waterintracellular water

Low molecular weight Low molecular weight cryoprotectants (e.g. cryoprotectants (e.g. sugars, polyols, amino sugars, polyols, amino acids) acids)

Antifreeze Antifreeze glycoproteinsglycoproteins


Processes of Heat TransferProcesses of Heat Transfer

Radiation = heat transfer through waves of energyRadiation = heat transfer through waves of energy Conduction = direct transfer of heat from one object to Conduction = direct transfer of heat from one object to

anotheranother Convection = heat transfer by circulation of a fluid (gas Convection = heat transfer by circulation of a fluid (gas

or liquid)or liquid) Evaporation = heat loss as water changes from liquid to Evaporation = heat loss as water changes from liquid to

vaporvapor MetabolismMetabolism

Morphological, physiological, or behavioral Morphological, physiological, or behavioral adaptations to thermal stress are limited to these adaptations to thermal stress are limited to these

five mechanismsfive mechanisms..

Physical Mechanisms of Heat Transfer Physical Mechanisms of Heat Transfer Determine Temperature AdaptationsDetermine Temperature Adaptations

Heat can be gained or lost by:Heat can be gained or lost by: ConductionConduction RadiationRadiation ConvectionConvection Evaporation of waterEvaporation of water MetabolismMetabolism• The morphological, physiological, or The morphological, physiological, or

behavioral adaptations to thermal stress are behavioral adaptations to thermal stress are limited to these five mechanisms.limited to these five mechanisms.


RadiationRadiation

Animals gain radiant heat directly from the Animals gain radiant heat directly from the sun and reflected from the atmosphere sun and reflected from the atmosphere and objects in the environmentand objects in the environment

Animals also lose heat as they radiate it to Animals also lose heat as they radiate it to their environmenttheir environment

Net gain during daytime, net loss at nightNet gain during daytime, net loss at night

ConductionConduction

Animals can either gain or lose heat to the Animals can either gain or lose heat to the ground or other objects depending on their ground or other objects depending on their relative temperaturesrelative temperatures

lizardlizard

rockrock

30°C30°C

20°C20°C

30°C30°C

40°C40°C

Animal loses heat when it’sAnimal loses heat when it’swarmer than contacted objectwarmer than contacted object

Animal gains heat when it’sAnimal gains heat when it’scooler than contacted objectcooler than contacted object

ConvectionConvection

Animals can gain or lose heat depending Animals can gain or lose heat depending on relative temperature of animal and fluidon relative temperature of animal and fluid

Typically animals lose heat through Typically animals lose heat through convection because their body convection because their body temperature is higher than air temperaturetemperature is higher than air temperature

Insulation of fur or feathers reduces Insulation of fur or feathers reduces convective heat lossconvective heat loss

brr!

EvaporationEvaporation

Always results in heat loss from the animalAlways results in heat loss from the animal Sweating, panting, and bathing are Sweating, panting, and bathing are

adaptations to increase evaporative heat adaptations to increase evaporative heat loss to prevent overheatingloss to prevent overheating

Physical Mechanisms of Heat Transfer Physical Mechanisms of Heat Transfer Determine Temperature AdaptationsDetermine Temperature Adaptations


Thermoregulation of HomeothermsThermoregulation of Homeotherms

Homeotherms maintain Homeotherms maintain constant Tconstant Tbb in a broad range of in a broad range of

TTenvenv

Metabolic rate increases Metabolic rate increases outside thermal neutral zoneoutside thermal neutral zone

Mechanisms of Mechanisms of thermoregulation: thermoregulation: Shivering thermogenesisShivering thermogenesis Non-shivering thermogenesisNon-shivering thermogenesis SweatingSweating PantingPanting

Bergmann’s RuleBergmann’s Rule

Individuals of a given species are larger in Individuals of a given species are larger in cold climates than in warm climates cold climates than in warm climates

(generally speaking)(generally speaking)

White-tailed deer skulls

Source: http://www.mun.ca/biology/scarr/Source: http://www.mun.ca/biology/scarr/Bergmann's_rule_in_Odocoileus.htmBergmann's_rule_in_Odocoileus.htm

Allen’s RuleAllen’s Rule

Individuals of a given species have shorter Individuals of a given species have shorter extremities in cold climates than in warm climatesextremities in cold climates than in warm climates

Arctic hareArctic hare- Arctic - Arctic tundratundra

Snowshoe hareSnowshoe hare- boreal forest- boreal forest

Black-tailedBlack-tailedjackrabbitjackrabbit- prairies- prairies

AntelopeAntelopejackrabbitjackrabbit- deserts- deserts

Source: http://www.mun.ca/biology/scarr/Lepus_variation.htmSource: http://www.mun.ca/biology/scarr/Lepus_variation.htm

(generally speaking)(generally speaking)

HOW SIZE MATTERS IN HOW SIZE MATTERS IN REGULATING BODY REGULATING BODY

TEMPERATURETEMPERATURE

ConceptConcept

Small-bodied animals or plant parts (e.g., Small-bodied animals or plant parts (e.g., leaves) heat up and cool down faster; leaves) heat up and cool down faster; bigger and/or thicker bodies heat up and bigger and/or thicker bodies heat up and cool down slower.cool down slower.

ExplanationExplanation

Smaller/thinner bodies have a larger Smaller/thinner bodies have a larger surface area to volume ratio. surface area to volume ratio. Bodies gain and lose heat out of the surface Bodies gain and lose heat out of the surface

of their body; more surface area means of their body; more surface area means greater gains and losses. greater gains and losses.

Bodies retain heat within their bodies; more Bodies retain heat within their bodies; more volume means more heat retention. When the volume means more heat retention. When the surface area is large compared to the volume surface area is large compared to the volume (small/thin things), heat is gained and lost (small/thin things), heat is gained and lost quickly.quickly.

Example: compare 1 cm x 1 cm x 1 cm Example: compare 1 cm x 1 cm x 1 cm cube with 10 cm x 10 cm x 10 cm cubecube with 10 cm x 10 cm x 10 cm cube

11

11

11

Surface area = 1x1x6 = 6 cmSurface area = 1x1x6 = 6 cm22

Volume = 1x1x1 = 1 cmVolume = 1x1x1 = 1 cm33

SA:V ratio = 6:1 = 6.0SA:V ratio = 6:1 = 6.0

10

1010

1010

Surface area = 10x10x6 = 600 cmSurface area = 10x10x6 = 600 cm22

Volume = 10x10x10 = 1000 cmVolume = 10x10x10 = 1000 cm33

SA:V ratio = 600:1000 = 0.6SA:V ratio = 600:1000 = 0.6

Small animalSmall animal

LargeLargeanimalanimal

SIZE MATTERSSIZE MATTERS

Small cookies cool down faster than larger Small cookies cool down faster than larger cookies after coming out of the oven. Also small cookies after coming out of the oven. Also small cookies burn faster. cookies burn faster.

Your hand has the same volume whether it is Your hand has the same volume whether it is balled up (fat) or spread out (thin). On a cold balled up (fat) or spread out (thin). On a cold day, your hand will get cold faster when spread day, your hand will get cold faster when spread out because balling up you hand into a fist out because balling up you hand into a fist effectively reduces surface area because now effectively reduces surface area because now the part of your hand within your fist is no longer the part of your hand within your fist is no longer "surface". "surface".

Advantages and Disadvantages to Advantages and Disadvantages to Being Large:Being Large:

Heat is gained and lost more slowly so, for Heat is gained and lost more slowly so, for example, on a hot summer day, the a large example, on a hot summer day, the a large animal may never reach lethal temperatures by animal may never reach lethal temperatures by the time the sun sets. the time the sun sets.

Because heat is lost more slowly, the animal Because heat is lost more slowly, the animal doesn't have to replace lost heat as quicklydoesn't have to replace lost heat as quickly Therefore, the animal doesn't have to eat as much Therefore, the animal doesn't have to eat as much

compared to its body weight (compared to its body weight (e.ge.g., only has to eat 1/4 ., only has to eat 1/4 its body weight). its body weight).

However, it usually does have to eat more total food However, it usually does have to eat more total food than a smaller animal. than a smaller animal.

Advantages and Disadvantages to Advantages and Disadvantages to Being Small:Being Small:

Heat is gained and lost faster so, for example, Heat is gained and lost faster so, for example, on a hot summer day, a small leaf (less than on a hot summer day, a small leaf (less than about 1 square centimeter) will shed heat as fast about 1 square centimeter) will shed heat as fast as it acquires heat as it acquires heat Therefore the leaf will never reach temperatures Therefore the leaf will never reach temperatures

higher than air temperature (compared to a large, higher than air temperature (compared to a large, thick leaf that acquires a heat load and can reach thick leaf that acquires a heat load and can reach very high, lethal temperatures). very high, lethal temperatures).

Because heat is lost faster, the animal has to eat Because heat is lost faster, the animal has to eat faster to replace the lost energy (e.g., very small faster to replace the lost energy (e.g., very small mammals may eat up to 4 times their body mammals may eat up to 4 times their body weight each day). weight each day).

Summary ExampleSummary Example

A plant can either have very small leaves A plant can either have very small leaves that never heat up higher than air that never heat up higher than air temperature or very large leaves that heat temperature or very large leaves that heat up so slowly that they never reach lethal up so slowly that they never reach lethal temperatures, but a plant doesn't want to temperatures, but a plant doesn't want to have leaves in the middle sizes if the have leaves in the middle sizes if the temperatures are going to be extremely temperatures are going to be extremely hot or cold.hot or cold.

Concepts Concepts Van't Hoff's RuleVan't Hoff's Rule: for every temperature rise of 10 degrees : for every temperature rise of 10 degrees

C, rate of biochemical reactions (most body functions) C, rate of biochemical reactions (most body functions) doubles, up to a point (when proteins break down). What is doubles, up to a point (when proteins break down). What is the other name of this law?the other name of this law?

Energy AllocationEnergy Allocation: all energy taken in by plants and animals : all energy taken in by plants and animals is portioned out (is portioned out (allocatedallocated) to the following areas) to the following areas GrowthGrowth ReproductionReproduction ActivityActivity MaintenanceMaintenance Storage.Storage.

Savings in one area (e.g., maintenance which includes Savings in one area (e.g., maintenance which includes thermoregulation) means more energy can be diverted to thermoregulation) means more energy can be diverted to other areas (e.g., storage for hard times later). other areas (e.g., storage for hard times later).

Types of Animals Based on Means Types of Animals Based on Means of Thermoregulation: of Thermoregulation:

EctothermsEctotherms: animals whose principal : animals whose principal source of body heat is the environment. source of body heat is the environment. Includes essentially all animals except Includes essentially all animals except birds and mammals. birds and mammals.

EndothermsEndotherms: animals whose principal : animals whose principal source of body heat is from their own body source of body heat is from their own body generating heat metabolically. Birds and generating heat metabolically. Birds and mammals are endotherms. mammals are endotherms.

Types of ThermoregulationTypes of Thermoregulation

Behavioral ThermoregulationBehavioral Thermoregulation: using posture, : using posture, orientation, and microclimate selection to orientation, and microclimate selection to regulate body temperature. For example, a regulate body temperature. For example, a lizard that wants to heat up will spread eagle lizard that wants to heat up will spread eagle (posture) on the top of a hot rock (microclimate) (posture) on the top of a hot rock (microclimate) and turn its entire back to the sun (orientation). and turn its entire back to the sun (orientation).

Physiological ThermoregulationPhysiological Thermoregulation: altering : altering metabolic generation of heat to regulate body metabolic generation of heat to regulate body temperature. temperature.

Poikilotherms (ectotherms)Poikilotherms (ectotherms)

No internal physiological mechanism for keeping No internal physiological mechanism for keeping body temp constantbody temp constant

Body temp matches environmental tempBody temp matches environmental temp As temp drops body processes slow downAs temp drops body processes slow down

Source of body heat is the environmentSource of body heat is the environment

PlantsPlants

ReptilesReptiles

AmphibiansAmphibians

MostMost fish fish

Most Most invertebratesinvertebrates

Coping with Temperature VariationCoping with Temperature VariationPoikilothermsPoikilotherms

BehaviorBehavior

When temp is low lizard sits broadside to sun and When temp is low lizard sits broadside to sun and presses belly against warm rockspresses belly against warm rocks

When temp is high lizard moves to shade, burrow, When temp is high lizard moves to shade, burrow, walks on tiptoewalks on tiptoe

When temp is too low lizard seeks protected habitat When temp is too low lizard seeks protected habitat and becomes inactive; outcome depends on how and becomes inactive; outcome depends on how cold it getscold it gets

ExampleExample

Desert IguanaDesert Iguana ( (Dipsosaurus dorsalisDipsosaurus dorsalis)) in the in the southwestern US desert. southwestern US desert.

In summer temperatures can exceed 45In summer temperatures can exceed 45ooC, and in C, and in winter temperatures are often below 0winter temperatures are often below 0oo

During mid-July the thermal environment changes During mid-July the thermal environment changes so rapidly that activity is limited to 45 minutes in so rapidly that activity is limited to 45 minutes in the morning, and 45 minutes in the afternoon. the morning, and 45 minutes in the afternoon.

Figure describes the diurnal and seasonal Figure describes the diurnal and seasonal pattern of behavior: pattern of behavior:


PhysiologyPhysiology

Produce chemicals that lower the freezing point Produce chemicals that lower the freezing point of cytoplasmof cytoplasm

Freeze-tolerant speciesFreeze-tolerant species - have ice-nucleating - have ice-nucleating agents (ECF freezes at lower temp than cytoplasm; agents (ECF freezes at lower temp than cytoplasm; prevents ice crystals)prevents ice crystals)

Freeze-tolerant insects do not really freeze, at least Freeze-tolerant insects do not really freeze, at least not totally. Just the fluid, which bathes their living not totally. Just the fluid, which bathes their living cells, freezes. This freezing process forces water out cells, freezes. This freezing process forces water out of the living cells thus lowering the freezing point of the living cells thus lowering the freezing point even further. (Smaller amounts of water freeze at even further. (Smaller amounts of water freeze at lower temperatures than larger amounts of water.)lower temperatures than larger amounts of water.)


Many plants; sessile marine organisms like barnacles; Many plants; sessile marine organisms like barnacles; orgs that overwinter in exposed places - insects; wood orgs that overwinter in exposed places - insects; wood frogsfrogs

Freeze-tolerant insects aren't necessarily more cold Freeze-tolerant insects aren't necessarily more cold tolerant than freeze-susceptible insects. Each class of tolerant than freeze-susceptible insects. Each class of insects just has its own unique survival strategy.insects just has its own unique survival strategy.


Freeze-susceptibleFreeze-susceptible - produce glycerol etc; facilitate - produce glycerol etc; facilitate supercooling; lower freezing point to avoid ice crystalssupercooling; lower freezing point to avoid ice crystals tropical and temperate plants and animals tropical and temperate plants and animals e.g. e.g. basilbasil

A freeze-susceptible insect avoids freezing altogether by A freeze-susceptible insect avoids freezing altogether by depending heavily on antifreeze compounds, called depending heavily on antifreeze compounds, called cryoprotectants, to supercool body fluids and tissues cryoprotectants, to supercool body fluids and tissues above their freezing point. above their freezing point. Ethylene glycol, the same compound found in Ethylene glycol, the same compound found in

antifreeze for cars, is the most common antifreeze for cars, is the most common cryoprotectant. cryoprotectant.

Antarctic icefishes, as they are now known, are the Antarctic icefishes, as they are now known, are the only vertebrates that lack red blood cells.only vertebrates that lack red blood cells.

Advantages of being an Advantages of being an EctothermEctotherm

Greater efficiency: allocate 30%-90% of Greater efficiency: allocate 30%-90% of ingested energy towards growth (<5% in ingested energy towards growth (<5% in most endotherms)most endotherms)

Lower energy demands: can tolerate long Lower energy demands: can tolerate long periods with low food availabilityperiods with low food availability

Less energetic cost for small body size: Less energetic cost for small body size: able to occupy more niches for small-able to occupy more niches for small-bodied animalsbodied animals

Large Ectotherms?Large Ectotherms?

As body size increases, As body size increases, surface area-to-volume ratio surface area-to-volume ratio decreases, and large decreases, and large ectotherms are thus ectotherms are thus improbable.improbable.

This had led to speculation This had led to speculation that large dinosaurs may that large dinosaurs may have had some degree of have had some degree of endothermy.endothermy.

Homeotherms (endotherms)Homeotherms (endotherms) Physiological mechanisms for controlling body tempPhysiological mechanisms for controlling body temp

Keeping warmKeeping warm Metabolic heat: increased metabolism, shiveringMetabolic heat: increased metabolism, shivering Insulation (fat, fluffed fur or feathers) e.g. Birds, mammalsInsulation (fat, fluffed fur or feathers) e.g. Birds, mammals Body size and shapeBody size and shape

Keeping coolKeeping cool Lower metabolic heat productionLower metabolic heat production Evaporation: panting, sweatEvaporation: panting, sweat Body size and shapeBody size and shape

BirdsBirds MammalsMammals

Range and limits of homeothermyRange and limits of homeothermy

Thermoneutral zone = range of environmental Thermoneutral zone = range of environmental temperatures over which an animal can maintain temperatures over which an animal can maintain a constant body temperature without raising its a constant body temperature without raising its metabolic ratemetabolic rate

Lower and upper critical temperatures = Lower and upper critical temperatures = environmental temperatures at which animal environmental temperatures at which animal must raise its metabolic rate to maintain must raise its metabolic rate to maintain homeothermyhomeothermy

Lower and upper lethal temperatures = Lower and upper lethal temperatures = environmental temperatures at which animal can environmental temperatures at which animal can no longer raise its metabolic rate and diesno longer raise its metabolic rate and dies

BehaviorBehavior Burrows, dens, Burrows, dens,

shade during shade during hottest part of dayhottest part of day

Sled dog, arctic fox Sled dog, arctic fox wrap tail around wrap tail around faceface

Grouse burrows Grouse burrows under snowunder snow

Gular flutteringGular fluttering UrohydrosisUrohydrosis

Coping with Temperature Coping with Temperature Variation Variation HomoiothermsHomoiotherms

UrohydrosisUrohydrosis Excretion on the feet or legs Excretion on the feet or legs

which evaporates and then which evaporates and then cools the organism as the cools the organism as the excretion evaporates excretion evaporates

This is a common This is a common adaptation in birds such as adaptation in birds such as turkey vultures. turkey vultures.

A similar adaptation is seen A similar adaptation is seen in Kangaroos which lick their in Kangaroos which lick their forearms to wet them with forearms to wet them with saliva. saliva.

Cactus Wren: Daily behavior reflects the temperature of the microhabitats used. The orientation of the nest changes during the breeding season in order to maximize cooling in this desert environment.

Coping with Temperature VariationCoping with Temperature VariationHomoiothermsHomoiotherms

MorphologyMorphology Coloration is thought to be an important factor in the Coloration is thought to be an important factor in the

reduction of heat absorption. reduction of heat absorption. A lighter colored coat will reflect more light relative to A lighter colored coat will reflect more light relative to

a darker coat which will absorb more light. The result a darker coat which will absorb more light. The result is reduced body temperatures and more water is reduced body temperatures and more water conservation. conservation.

Insulation in the form of feathers, hair, or even body fat Insulation in the form of feathers, hair, or even body fat which protects tissues beneath by insulation.which protects tissues beneath by insulation.

Enlarged appendages (desert Jackrabbit’s ears) in Enlarged appendages (desert Jackrabbit’s ears) in order to increase surface area and hence promote heat order to increase surface area and hence promote heat loss. loss.

Desert Jackrabbit

Arabian oryx

Coping with Temperature VariationCoping with Temperature VariationHomoiothermsHomoiotherms

Physiology – keeping warm Physiology – keeping warm requires lots requires lots of foodof food Increased body fat for cold weather insulationIncreased body fat for cold weather insulation Increased metabolic rateIncreased metabolic rate Shivering (heat from muscle activity)Shivering (heat from muscle activity) Increase air spaces by fluffing feathers, furIncrease air spaces by fluffing feathers, fur Counter current mechanismsCounter current mechanisms

During the winter, the Willow Ptarmigan produces a denser coat of feathers and actually down-regulates its basal metabolism, which reduces the gradient between the internal body temperature and the external temperature. This is the same as keeping your house at a cooler temperature in order to reduce your heating bill. Both responses reduce the amount of energy necessary to stay warm.

Metabolic Heat ProductionMetabolic Heat Production

Endotherms produce heat by oxidizing energy-Endotherms produce heat by oxidizing energy-rich carbohydrate moleculesrich carbohydrate molecules

Some of the energy is stored but much is Some of the energy is stored but much is dissipated as heatdissipated as heat

Metabolic rate = rate at which energy-releasing Metabolic rate = rate at which energy-releasing chemical reactions occurchemical reactions occur

Basal (standard) metabolic rate = lowest rate of Basal (standard) metabolic rate = lowest rate of energy expenditure of resting, fasting animal in energy expenditure of resting, fasting animal in its comfortable temperature rangeits comfortable temperature range

CC66HH1212OO66 + 6 O + 6 O22 → 6 CO → 6 CO22 + 6 H + 6 H22O + energyO + energy

Counter current heat exchange

Mammalian Counter Current Example

Thermoregulation in HomeothermsThermoregulation in HomeothermsCountercurrent heat exchangersCountercurrent heat exchangers

36°C

28°C


Reduce Heat InputReduce Heat Input

Staying out of the sunStaying out of the sun Shading (e.g., spines/fur)Shading (e.g., spines/fur) Posture and orientation (e.g., orienting Posture and orientation (e.g., orienting

leaves vertically to minimize surface area leaves vertically to minimize surface area directly hit by sun)directly hit by sun)

InsulationInsulation Shiny surfaces that reflect sun, etc. Shiny surfaces that reflect sun, etc.

Dissipating HeatDissipating Heat

If heat reduction wasn't If heat reduction wasn't enough, then it is time to enough, then it is time to get rid of body heat byget rid of body heat by evaporation (costs water evaporation (costs water

though), though), long appendages (legs, long appendages (legs,

ears, etc.), or ears, etc.), or small "bodies" (e.g., small "bodies" (e.g.,

whole body, leaves, etc.) whole body, leaves, etc.) that radiate heat. that radiate heat.

Tolerate HyperthermiaTolerate Hyperthermia

Some plants and animals Some plants and animals can survive body can survive body temperatures that would temperatures that would be dangerous to humans be dangerous to humans (e.g., this antelope (e.g., this antelope ground squirrel tolerates ground squirrel tolerates body temperatures over body temperatures over 104 degrees F!). 104 degrees F!).

Advantages of being an endothermAdvantages of being an endotherm

Tolerate a wider range of Tolerate a wider range of environmental conditionsenvironmental conditions

Can be active day or night, Can be active day or night, year roundyear round

Can sustain high levels of Can sustain high levels of activity for longer periods activity for longer periods because rely more on because rely more on aerobic metabolism aerobic metabolism (anaerabic in ectotherms)(anaerabic in ectotherms)

Disadvantages of HomeothermyDisadvantages of Homeothermy

Homoiotherms can’t shut down completely if food, Homoiotherms can’t shut down completely if food, water, or oxygen disappearwater, or oxygen disappear

Homeotherms can’t be as small as poikilotherms. Homeotherms can’t be as small as poikilotherms. Lose too much heat as SA/V increases and can’t eat enough Lose too much heat as SA/V increases and can’t eat enough

to keep warm. to keep warm.

Homeotherms can't be wormlike or snakelike in shape. Homeotherms can't be wormlike or snakelike in shape. High SA/V - lose too much heat.High SA/V - lose too much heat.

Aquatic env favors poikilotherms because of high rate Aquatic env favors poikilotherms because of high rate of convection.of convection.

Other AdaptationsOther Adaptations Partial homeothermyPartial homeothermy - - Swordfish, Tuna, GW SharksSwordfish, Tuna, GW Sharks

Hunts near surface during the day; goes deep at nightHunts near surface during the day; goes deep at night T may be as much as 19T may be as much as 19oocc Has brain-eye heater to keep these organs at stable temp Has brain-eye heater to keep these organs at stable temp

(needed for hunting)(needed for hunting) Tissue rich in mitochondria; countercurrent blood supply; Tissue rich in mitochondria; countercurrent blood supply;

thick layer of fat around brain and eyesthick layer of fat around brain and eyes

HeterothermsHeterotherms - - warm-blooded species that warm-blooded species that hibernate (temporary poikilothermy)hibernate (temporary poikilothermy)

Temporary homeothermyTemporary homeothermy during egg incubation by during egg incubation by some snakessome snakes

Heat stable enzymesHeat stable enzymes in thermophilic bacteria in thermophilic bacteria

Endothermy in insectsEndothermy in insects: : sphinx mothssphinx moths

active moths maintain active moths maintain constant metabolic rateconstant metabolic rate

regulate body temp by regulate body temp by modifying cooling ratemodifying cooling rate

heat produced by flight heat produced by flight muscles in thorax is muscles in thorax is transported via transported via circulatory system to circulatory system to abdomenabdomen

Ecology of BumblebeesEcology of Bumblebees

Bumblebees live in many cool Bumblebees live in many cool regions.regions. Bernd HeinrichBernd Heinrich estimated the estimated the

energy budgetenergy budget of individuals of individuals foraging on different flowers foraging on different flowers and under different and under different temperatures.temperatures.

Energy Gain / LossEnergy Gain / Loss

Energy Intake - Energy Energy Intake - Energy ExpenditureExpenditure..

How to Keep WarmHow to Keep WarmMore ExamplesMore Examples

BaskBask

Compact BodyCompact Body

ShiverShiver

HibernateHibernate

HibernateHibernate

The Grizzled Checkerspot butterfly also is The Grizzled Checkerspot butterfly also is very short lived as an adult. As a very short lived as an adult. As a caterpillar, it takes two summers of eating caterpillar, it takes two summers of eating before it is ready to pupate and before it is ready to pupate and metamorphose into an adult butterfly, so it metamorphose into an adult butterfly, so it has to hibernate twice. Since most of this has to hibernate twice. Since most of this species is on the same two-year cycle, species is on the same two-year cycle, you are only likely to see these butterflies you are only likely to see these butterflies in odd years!in odd years!

Burrow Below GroundBurrow Below Ground

"Gopher Eskers" "Gopher Eskers"

Burrow Below GroundBurrow Below Ground

Pocket GopherPocket Gopher

Stay Awake and Hoard FoodStay Awake and Hoard Food

MigrateMigrate

homeostasis in animals temperature. how do physiological adaptations alter the organism’s...

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