lecture 4 the distribution of life: physical and biologicalsd1229/364/364.lecture4.pdf ·...

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Lecture 4The Distribution of Life: Physical and Biological

Lecture 4The Distribution of Life: Physical and Biological

I. The Physical EnvironmentA. LightB. TemperatureC. MoistureD. Environmental Gradients and Species Niches

II. Biological InteractionsA. PredationB. CompetitionC. SymbiosisD. Physical and Biological Controls at work

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Lecture 4The Distribution of Life

I. The Physical EnvironmentA. Light

Light6CO2 + 12H2O C6H12O6 + 6H2O +6O2Carbon Water Sugar Water OxygenDioxide



(Adiantum aleuticum) (Salvia leucophylla)

HeliophyteSciophyte

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Adaptations for living in high or low light intensities.

1. Physiological



Adaptations for living in high or low light intensities.

2. Morphological

(Arctostaphylos patula)

(Yucca schidigera)

Sciotrophic leaves

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Adaptations for living in high or low light intensities.2. Life history and reproductive behavior

Ex. annuals


Distribution of Earth’s Forests

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I. The Physical EnvironmentB. Temperature

1. Plants (poikilotherms)




Plant adaptations to cold temperatures:a. Deciduous leaves (maple, beech, birch, and ashes)b. Supercooling and extracellular water loss (pine, spruce,

and fir trees)c. Heat re-radiation (saguaro cactus)

(Carnegiea gigantea)Spruce tree(Picea sp.)Big leaf maple

(Acer macrophyllum)

a. b. c.

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Plant adaptations to warm temperatures:a. Dimorphic leaves (sage scrub in southern California)b. Waxy leaves (any cactus)c. Water storage capacity (cactus, baobab tree, etc.)

Sagebrush(Artemesia californica)

Baobab Tree(Adansonia

digitata)



2. Animals

Poikilotherms - a.k.a.ectotherms (fish, reptiles, amphibians)Homeotherms – a.k.a. endotherms (birds and mammals)

Antarctic icefish(Trematomus borchgrevinki)

San Joaquin Kit Fox(Vulpes macrotis)

EurythermicVs.

Stenothermic

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2. Animals

Animal adaptations to warm environments:a. Differences in metabolic rate

b. Release of sweat or panting


a. Use of microclimate (reptiles and insects)

Animal adaptations to warm environments:

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2. AnimalsAnimal adaptations to warm

environments:a. Morphological adaptations

Chameleon(Chamaeleo calyptratus)

African elephant(Loxodonta africana)



2. AnimalsAnimal adaptations to cold environments:a. Hibernation, torpor,

(Ursus arctos)

(Taxidea taxus)

(Chordeilesacutipennis )

(Lasiurus spp.)

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2. AnimalsAnimal adaptations to cold environments:a. Hibernationb. Changes in metabolism with changes in air temperature



2. AnimalsAnimal adaptations to cold environments:c. Morphology

Polar bear(Thalarctos maritimus)

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2. Animals

Allen’s Rule: Animals that live in cold environments have shorter

extremities (relative to body mass) than related forms in warm environments.

Arctic hare(Lepus arcticus)

Jack rabbit(Lepus californicus)


I. The Physical EnvironmentC. Moisture

1. Xerophyte 2. Hydrophyte 3. Mesophyte

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I. The Physical EnvironmentC. Water

Plant adaptations to dry conditions:a. Water stress escapeesb. Water stress avoidersc. Water stress tolerators

Baobab tree (Adensonia digitata)

Poppies(Eschscholzia spp.)

Chamise(Adenostoma fasciulatum)



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The Impact of moisture on terrestrial animals:

• Most mammals can withstand a loss of about 10% of their body water

• Frogs can use as much as 40% of their body water• Water is replenished by drinking from free water such as

lakes, streams, springs, and dew on leaves• Water can be replenished via food for some species

(Kangaroo rate)


I. The Physical EnvironmentD. Environmental Gradients and Species Niches

Fig. 3.12: The range and population density of eastern Bluebird (Sialia sialis)

• Geographic range• Density

• Carrying capacity

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I. The Physical EnvironmentD. Environmental Gradients and Species Niches

Air temperature

Soi

l moi

stur

e

• Niche • Habitat• Generalist• Specialist

Figure 3.14. The niches of hypothetical plant species as defined by two gradients.


I. Biological InteractionsA. Predation

• Stenophagus• Euryphagous

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