Desert Life

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Desert Life
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Desert ecology
Desert ecology

• Why are deserts dry?
• What adaptations to animals and plants need to
  live there?

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Deserts
Desert ecology

• Definition of a desert less than 10 inches of
  rain per year, more evaporation than
  precipitation
• This is caused either by dry winds (air heating
  up as it gets warmer), a mountain rainshadow,
  or lack of water in the middle of a continent

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Why are deserts dry?
Desert ecology

• Rainshadow of mountain / middle of continent
• Falling air / cool air holds little moisture
• and at this latitude, air often falls from
  having risen at the equator

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Deserts
Desert ecology
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North American Deserts
Desert ecology

• Sonoran Desert
• Mojave Desert
• Chihuahuan Desert
• Great Basin Desert

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North American Deserts
Desert ecology

• Characteristic plants
• Sonoran Desert Saguaro, cacti
• Mojave Desert Joshua tree
• Chihuahuan Desert yuccas
• Great Basin Desert sagebush

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Why does any organism live where it lives?
The abiotic environment

• Usually three kinds of explanations
• Abiotic environment (the right climate, nesting
  sites, etc.)
• Biotic interactions (prey is there)
• History (it evolved there and did not migrate
  somewhere else)

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Why are most cacti only found in the American
deserts?
The abiotic environment

• Abiotic environment (dry with periodic rain not
  too cold)
• Biotic interactions (can defend themselves
  against desert herbivores and compete with other
  desert plants)
• History (evolved in the Americas, and cannot
  migrate to Africa, for example)

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North American Deserts
Desert ecology

• Characteristic plants because of characteristic
  climate
• Sonoran Desert winter and summer rains
  (monsoon), very hot
• Mojave Desert winter rains, hot
• Chihuahuan Desert summer rains, warm
• Great Basin Desert winter rains, high elevation,
  colder (especially in winter)

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Desert adaptations
Desert ecology

• Animals and plants that live in the desert are
  adapted to the hot, dry climate.
• Three basic methods
• Evade
• Endure
• Expire

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Evade Endure Expire
Desert ecology

• Adults may die before it gets too hot
• Durable eggs or seeds survive to next wet season

• Migrate away in summer
• Only be active at night

• Minimize water loss
• Maximize heat loss
• Store water

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Endure ways to cope with hot dry climate
Desert ecology

• Store water
• Conserve water
• Tolerate dehydration
• Reduce heat input
• Dissipate heat
• Tolerate hypothermia

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Endure ways to cope with hot dry climate
Desert ecology

• Store water
• Conserve water
• Tolerate dehydration
• Reduce heat input
• Dissipate heat
• Tolerate hypothermia

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Endure ways to cope with hot dry climate
Desert ecology

• Store water
• Conserve water
• Tolerate dehydration
• Reduce heat input
• Dissipate heat
• Tolerate hypothermia

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Endure ways to cope with hot dry climate
Desert ecology

• Store water
• Conserve water
• Tolerate dehydration
• Reduce heat input
• Dissipate heat
• Tolerate hypothermia

vertical leaves, insulation with hairs
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Endure ways to cope with hot dry climate
Desert ecology

• Store water
• Conserve water
• Tolerate dehydration
• Reduce heat input
• Dissipate heat
• Tolerate hypothermia

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Endure ways to cope with hot dry climate
Desert ecology

• Store water
• Conserve water
• Tolerate dehydration
• Reduce heat input
• Dissipate heat
• Tolerate hypothermia

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Deserts
Summary

• Deserts are drier than other places
• But there are different kinds of deserts
  depending on the temperature, seasons, and when
  how much rain
• Animals and plants are adapted to a particular
  niche, which includes climate and other species
• Where an animal/plant lives also has historic
  reasons