Endothermy and Ectothermy

Ch. 6.7, Bush

Outline

Effects of temperature on life

Thermoregulation

Ecological aspects of thermoregulation

Outline

Effects of temperature on life

Thermoregulation

Ecological aspects of thermoregulation

Effects of extreme temperatures

Cold -- the effects of freezing– physical damage to structures caused by the formation of

ice; the membrane bound structures are destroyed or damaged.

Heat– inadequate O2 supply for metabolic demands (especially in

areas where O2 is low, such as water)

Heat and Cold– reduced activity or denaturation of proteins -- the

inactivation of certain proteins with the result that metabolic pathways are distorted.

Optimal temperature for enzyme functioning

Body Temperature

Law of Tolerance:– for most requirements of life, there is an

optimal quantity, above and below which the organism performs poorly

There is much variation in the range of temperatures that a species can tolerate

Outline

Effects of temperature on life

Thermoregulation

Ecological aspects of thermoregulation

Thermoregulation

maintenance of internal temperature within a range that allows cells to function efficiently

Two main types– ectothermy – endothermy

Endothermy versus ectothermy

Ectothermy

an animal that relies on external environment for temperature control instead of generating its own body heat

“cold-blooded”

e.g., invertebrates, reptiles, amphibians, and most fish

the majority of animals are ectotherms

Metabolism and temperature

ectotherms cannot move very much unless the ambient temperature allows

roughly, for each 10 degree increase in temperature, there is a 2.5 increase in metabolic activity

Ectothermy

Desert iguanas are active only when ambient temperature is close to optimal for them

Ectothermic animals

Endothermy

a warm-blooded animal that controls its body temperature by producing its own heat through metabolism

evolved approximately 140 mya

E.g., birds, mammals, marsupial, some active fish like the great white shark and swordfish

Endothermic animals

Outline

Endothermy versus ectothermy

Behavioural adaptations to thermoregulation

Physiological adaptations to thermoregulation

Behavioural adaptations for thermoregulation

animals often bathe in water to cool off or bask in the sun to heat up

Shivering, sweating, and panting

honeybees survive harsh winters by clustering together and shivering, which generates metabolic heat

Inefficient – 75% of energy is lost in mechanical movement

Torpor

metabolism decreases heart and respiratory

system slow down body temperature

decreases conserves energy when

food supplies are low and environmental temps are extreme

E.g., hummingbirds on cold nights

Hibernation

Long-term torpor

adaptation for winter cold and food scarcity

E.g., ground squirrels

Aestivation

summer torpor

adaptation for high temperatures and scarce water supplies

E.g., mud turtles, snails

Endothermy and the evolution of sleep?

evolutionary remnant of torpor of our ancestors

the body needs sleep in order to offset the high energy costs of endothermy: – When animals fall asleep their metabolic

rates decrease by approximately ten percent

Colour and Posture

Change coloration (darker colors absorb more heat)– E.g., lizards, butterflies,

crabs

Posture:– Change shape (flatten

out to heat up quickly)– Orientation changes

Chemical adaptations

Many Canadian butterflies overwinter here and hibernate

they produce sugar-like substances as antifreeze

E.g., Mourning Cloak butterfly

Outline

Effects of temperature on life

Thermoregulation

Ecological aspects of thermoregulation

Advantages & Disadvantages of Endothermy

Advantages:– external temperature does not affect their

performance– allows them to live in colder habitats – muscles can provide more sustained power

– e.g., a horse can move for much longer periods than a crocodile can

Disadvantage:– energy expensive

– an endotherm will have to eat much more than an ectotherm of equivalent size

Where can endotherms thrive?

Higher latitudes and deserts

Terrestrial environments have more variation in daily and seasonal temperature which contributes to more endotherms in terrestrial environments

endotherms (mammals and birds) generally outcompete ectotherms if they are after the same food source

Size and thermoregulation

Small mammals (such as mice and shrews) have a greater dependence on internally-generated heat than big mammals (such as elephants and hippos)

leads to:– presence of insulation (fur - large mammals

generally have less hair) – voracious appetites of small mammals (a shrew

eats more per unit body weight than an elephant does)

Surface area to volume ratios

Ectothermy vs. endothermy

Many more ectotherms are small in size versus endotherms

Ectotherms typically have no insulation

Posture is different

Where do ectotherms thrive?

Where food items are:– scarce– small

In environments low in O2

Ecosystem functioning and ectothermy

Production Efficiency:-can be seen as the ratio of assimilation between

trophic levels

= biomass of predator

biomass of food species

Ectotherms are more efficient than endotherms (up to 15% versus 7%)

Thermoregulation and food chains

Endotherms are often the top predator in food chains

Food chains with lots of ectotherms are often longer in length

Summary

Endothermic animals regulate their body heat to stay within the optimal range for performance while the temperature of ectothermic animals fluctuates with that of the surrounding environment

Both endotherms and ectotherms have a variety of behavioural and physiological adaptations to deal with environmental extremes

Climate

Ch. 4, Bush

Outline

Climate and ecology

Solar energy and air circulation

Oceanic influences

Cycles of climate change

Outline

Climate and ecology

Solar energy and air circulation

Oceanic influences

Cycles of climate change

Climate affects ecology

Temperature and precipitation

Outline

Climate and ecology

Solar energy and air circulation

Oceanic influences

Cycles of climate change

Solar energy

Solar energy distribution is not balanced across the globe in– intensity– constancy

Together, these differences explain the distribution of tropical and temperate climates

Intensity of Solar energy

Solar energy is more intense at lower latitudes (that is, closer to the equator) because:

• the “footprint” of the beam of energy is smaller at tropical latitudes

• beams have shorter passage through the atmosphere

Intensity of solar energy

more energy per square meter in the tropics than at the poles

Differences in daylength

Differences in Day Length

caused by the constant tilt of Earth as it orbits around the sun

the reason why temperate environments have four seasons while tropical environments do not

Heat and air circulation

The disparity in energy input across the globe drives all our weather systems

This is because heat energy must flow from warm to cold

Hadley cells – the effect of heat transfer

Hot air rises and, as it rises, it cools

Cool air cannot hold as much moisture as heated air, so it rains

This cool, dry air must go somewhere so it pushes towards the poles, where it slows and descends

As it descends, it is warmed

Hadley cells

Hadley cells and climate

The downdraft of hot dry air causes the formation of the desert regions of Earth:

E.g., SaharaSonoranAustralianGobiAtacama

Equatorial rainforest

Average temp:– 20-34 ° C

Average rainfall:– 124-660 cm

Deserts – caused by downdrafts of hot, dry air

Average temp:– 20 to 25° C

Average rainfall:– under 15 cm a year

Movement of the thermal equator

Hadley cells

Intertropical convergence zone (ITCZ)

Movement of the ITCZ

responsible for wet and dry seasons of the tropics

Seasonality and ITZC

In temperate latitudes, seasonality is closely related to day length

In tropical latitudes, seasonality is closely associated with rainfall.

Tropical rainfall influences:– Germination, flowering, and fruiting in plants– Breeding, feeding, migration, and life history

strategies in animals

Movement of the ITCZ

hurricanes are spawned at the most northerly edge of the ITCZ

Outline

Climate and ecology

Solar energy and air circulation

Oceanic influences

Cycles of climate change

Ocean and heat transfer

water takes more energy to heat than land or air

Water moderates climate

The ocean makes coastal regions havemilder climates

Intertropical convergence zone (ITCZ)

Gulf Stream

Gulf Stream comes up from Gulf of Mexico, across Atlantic Ocean, to moderate climate of Western Europe

Effects of the Gulf Stream

The Gulf Stream makes snow rare in London but common in Toronto:

Altitude Ave. Temp (Jan)

London 51 N 6 C

Toronto 43 N -4 C

Earth’s rotation causes the Coriolis effect

Both objects A and B make one rotation on the Earth’s axis per day

An object located at the equator is rotating faster than an object at the pole

Coriolis Effect

Earth rotates eastward making all object deflect in this direction

http://www.eoascientific.com/campus/earth/multimedia/coriolis/view_interactive

Coriolis Effect and air circulation

Trade winds and the Gulf Stream

Major water currents

Outline

Climate and ecology

Solar energy and air circulation

Oceanic influences

Cycles of climate change

Cycles of Climate Change

There are two main cycles of climate change that are natural:

– El Nino Oscillation

– Glaciation

Gulf Stream

Gulf Stream comes up from Gulf of Mexico, across Atlantic Ocean, to moderate climate of Western Europe

Gulf Stream causes ocean currents

Warm water evaporates Ocean becomes more salty Loses heat as it moves towards pole Water becomes more dense as it becomes

more salty and/or loses heat This dense, cold, salty water sinking off the

coast of Greenland sets in motion an immense flow of water through the oceans

Ocean currents

El Nino Southern Oscillation (ENSO)

A decrease in wind speed of the Trade Winds off Tahiti is observed every 3-7 years

causes less warm surface water being piled up around Indonesia

Instead, warm surface water piles up off Peru in South America

El Nino Southern Oscillation (ENSO)

El Nino Effects

El Nino and Hurricane Pauline

El Nino and ecology

Evidence indicates that Galapagos marine iguanas actually shrink during El Nino events

El Nino reduces food supply (green and red algae)

El Nino and Insect outbreaks

In a dry lowland forest near Panama's Pacific coast, moth larvae devoured 250 percent more leaf material than usual

Bartonellosis, an insect-borne disease highly fatal to humans, are closely related to the climate event El Niño

Glacial and Interglacial periods

In the last 4 million years there have been at least 22 ice ages (= glacial periods)

Warm periods between glacial periods (interglacial) periods have been brief

In general…

Interglacial periods – mild in temperature and with more precipitation--

periods of diversification and range expansion in organisms adapted to warmer conditions

Glacial periods – fragmentation of plant and animal ranges (except

for arctic or cold-desert adapted organisms)

Glaciation and water level changes

About 3 million years ago, a major Ice Age began when the sea level dropped enough to expose the Isthmus of Panama

The Panama land bridge made possible one of the great events in biology-the interchange of species of two continents.

Glaciation and land changes

Moving into South America were:– fox; deer; tapir;

spectacled bear; spotted cat; llama.

Moving into North America were: – parrot; toucan,

armadillo; giant sloth; howler monkey; anteater; and capybara

Last glacial period ended 11,000 years ago

90% of last 2 million years has been glacial

For the last 10,000 years, plants and animals have been living in an unusually warm environment

Summary

Most weather patterns are ultimately caused by the fact that equatorial regions receive more solar energy than polar regions

– Location of tropical, temperate and desert ecosystems

– Wind and water currents– Seasonality of the tropics

Weather and climate fluctuate over relatively short time frames and relatively long ones