effects of temperature

8/2/2019 Effects of Temperature

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EFFECTS OFEFFECTS OF

TEMPERATURETEMPERATUREByByPritesh KrishnakumarPritesh Krishnakumar


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Nature of TemperatureNature of Temperature

Measure of the intensity of heat in terms ofa standardized unit.

Essential environmental factor whichinfluences all forms of life.

Acts as a limiting factor for the growth anddistribution of plants and animals .

Commonly expressed in the Celsius orFahrenheit scale.


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Modes of Heat TransferModes of Heat Transfer

Conduction: Conduction is the movement of heatthrough a substance by the collision of molecules.

Convection: Convection occurs when warmer areas ofa liquid or gas rise to cooler areas in the liquid or gasthus the cooler fluid comes to fill the void created.

Radiation: Radiation is a method of heat transfer thatdoes not rely upon any contact between the heat sourceand the heated object.


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Radiant energy of the sun is important inthe maintenance of homeothermy and

warmth of the biosphere.

Stefans Boltzmann law states that theamount of radiation emitted from a blackbody is (T)4 .


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Fates of radiant energyFates of radiant energy

Reflected by the surfaceno thermalbenefitfalls in the visible portion of the

electromagnetic spectrum. Transmitted solar energyno thermalbenefit ..

Absorbed energy essential forphysiological processgreatest amount ofenergy absorbed when sunlight falls surface


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Response to TemperatureResponse to TemperatureChange..Change..

Thermal history

Genetic difference

Diet Size

Sex

Hormones Stage in life cycle


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Effects on PlantsEffects on Plants

Photosynthesis: Increases with temperature to apoint. Photosynthesis is slowed down at lowtemperatures. Since photosynthesis is slowed, growth isslowed, and this results in lower yields.

Respiration: Rapidly increases with temperature.

Transpiration: Increases with temperature.

Flowering: May be partially triggered by temperature.Chrysanthemums will flower for a longer period of time ifdaylight temperatures are 50F. The Christmas cactusforms flowers as a result of short days and lowtemperatures.


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Sugar storage: Low temperatures reduce energyuse and increase sugar storage.

Dormancy: Warmth, after a period of lowtemperature, will break dormancy and the plantwill resume active growth.

Plants produce maximum growth when exposedto a day temperature that is about 10 to 15Fhigher than the night temperature.


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Adaptations (Plants)Adaptations (Plants)

Desert plants must cope with extremes intemperature

Most desert plant adaptations seem to be

geared towards minimizing water loss Fuzzy or hairy leaf surface Shiny, reflective leaves Small leaves

Deep tap roots


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Extensive surface roots Thicker leaves

Leaf orientation such that minimizesarea exposed to midday heat Spines instead of leaves

Thicker leaves


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Xerophytes, have adapted their physical structure to suitthe rigors such a harsh environment .

smaller leaves, grow compactly, and a non-porouscovering on their leaves such as wax. Hair on the leaves

of plants helps to reduce the evaporation of moisture.

Some desert plants the cells, can also survive extremedehyration then rehydrate when water is available withlittle or no damage to the cells.

Phreatophytes, have adapted root systems that are longenough to reach underground water


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Other plants cope with the extremes intemperature and rainfall by becomingdormant during the winter or droughts .Eg. genus such as Lomatium, store

energy within their roots when they

bloom in spring and set seed.

This stored energy isenough to survive for most of the

year in a dormant state.


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Trees must have adaptations to survivethe cold and drying conditions of winter.

Broadleaf trees (hardwoods) drop theirleaves during the winter, avoiding theproblems of maintaining foliage in cold anddry conditions

The adaptation from broadleaf to narrowneedle-like structures limits water lossthrough transpiration


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Conifers (softwoods) retain foliage andhave special adaptations in order to do so(better stomate control and a waxy coatingcalled cutin).


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Few important termsFew important terms

Warm blooded homeotherm endotherm

Cold blooded poikilotherm ectotherm

Homeotherm vs. poikilotherm implies an animal that canmaintain a specific body temperature versus an animalthat has a body temperature that varies with the ambienttemperature.

Endotherm vs. ectotherm implies an animal that

produces its own heat from within versus one that doesnot.


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Effects on AnimalsEffects on Animals

Temperatures effect onMetabolism: regulated by enzymes which

are influenced by temperature .So intemperature up to a certain limitenzymatic activity ,metabolism.

Reproduction: Gametogenesis and

liberation of gametes takes place at aspecific temperature .Temperature alsodetermines breeding seasons.


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Sex determination: Temperaturedependent sex determination (TSD) is aphenomenon seen in a number of reptilianspecies . Eg. In Nile crocs temperatures below 31.7degrees Celsius -females.

31.7- 34.5 degrees Celsius- males

34.5 degrees femalesColouration : In warm humid climates animals

bear darker pigmentation than some speciesfound in cool climates. (Glogers rule)


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Morphology: Birds and animals attain agreater body size when they are in coldregions (Bergmann's Rule) . Eg. Polarbears and Black bears.


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The extremities of mammals like tail, snout andears are relatively shorter in colder parts than inwarmer climates. (Allens rule) Eg. The ears of the

arctic fox is smaller than the red fox


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Cyclomorphosis : Relation betweenseasonal changes of temperature andbody form is termed as cyclomorphosis.Eg. Daphnia during the warm months develops a headplate in summer which is greatly reduced in the winter.


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Animal behaviour : Animals sense heatand prey on mammals and birds whosebody heat is higher than the enviromentaltemperature. Eg the pit viper can locate its preydue to the heat radiating from it .


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AdaptationsAdaptations Migration and Movement. Many species migrate

between seasons. Some, such as the arctic tern, travel10,000 miles between winter and summer habitats.

Torpidity is a controlled reduction of body metabolism,

evidenced by low oxygen consumption rates and lowerbody temperatures. A key part of the definition isaccurate metabolic control. In the north, hibernation isthe most dramatic form. Torpidity is not restricted tonorthern species and can be found in the tropics,

too. Estivation is a kind of torpidity in very hot and dryconditions.


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Acclimatization:Regulation in Endotherms

1. 38-42 C is the ideal and most efficient temperature

for biological reactions. All endotherms regulate at thesetemperatures. 2. The mammalian "thermostat" is located in the

hypothalmus of the brain - the 'master endocrine gland'. 3. Temperature sensors in the skin elicit behavioral

temperature adaptations. 4. The largest amount of endotherm heat comes from

the thoracic cavity and much of that heat is produced bythe smooth muscles.


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Decreasing the surface area of blood exposureto the environment

Insulation - fur, hair, blubber, feathers, insectscales, coats.

Counter-current heat exchange can be usedto prevent heat loss to extremities and is verycommonly used

Evaporative cooling.

pantinglickingurination onto the legs


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Ectotherm body temperature regulation.Ectotherms are often found to regulate their bodytemperature well by behavioral mechanisms.

Move to warmer or cooler areas (rocks, water, burrows,etc.)

Change coloration (darker colors absorb more heat) Change surface area (larger surface area will lead to

more heat exchange either in or out depending upon the

differential of temperature between the animal and theenvironment) evaporative cooling (e.g. panting)


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Thank you for your undivided attention!!!

effects of temperature

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