Abiotic Factors and Limits

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Abiotic Factors and Limits

• Part II

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Plant adaptations

• Leaf size
• Leaf shape
• Leaf thickness
• Dropping leaves
• Parabolic flower shape
• Flower orientation
• Water loss because of temperature (CAM)
• Switching life-history habits

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Adaptations for Water Balance
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Physiological Ecology of Water

• Water is polar (cohesion, adhesion)
• High heat capacity and heat of vaporization
• Medium for compounds in solution and reactions to
  occur
• Osmosis (hypertonic, hypotonic)
• Osmoconformers, osmoregulators (starfish,
  oysters, crabs, annelids)
• Euryhaline tolerate wide variation in salt
  concentration
• Stenohaline require narrow range of salt
  concentration in environment

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Animal adaptations

• In marine environments
• Maintain high internal solute concentrations
• or, Drink lots of seawater, urinate like crazy
• In freshwater environments
• Urinate like crazy, active ion-exchange

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The move to land

• Predator-free environment
• Higher oxygen availability
• But water at a premium!
• Greatest water-loss avenue Evaporation (sweating
  and breathing, some excretion)
• Adaptations include
• Behavioral staying in moist environments, being
  nocturnal, living underground
• Structural Integument (keratinized, chitin, wax)

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The move to land

• Water lost through waste (urine, feces)
• Digestive tract reclaims water (length)
• Urine form (ammonia, urea, uric acid)
• Metabolic water (fats and carbs) (kangaroo rat)

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Plant Adaptation

• Water absorbed through roots
• Single large taproot, branched shallow roots
• Soil type affects water availability (particle
  size, water potential)
• Waxy cuticle, stomata, cacti no leaves (reduce
  surface area spines for still air)
• C3, C4, CAM metabolism
• 6CO2 12H2O light energy ---gt C6H12O6 6O2
  6H2O

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Adaptations to Light Stimuli
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Animals

• Phototaxis (microorganisms, maggots)
• Timing for life-history events (reproduction,
  molting, etc)
• Otherwise, most animals do not have a strict
  requirement for light. Some live in complete
  darkness.

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Plants

• Extremely important
• Various photosynthetic pigments
• Leaf orientation
• Leaf shape (curling)

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Adaptations to Nutrient Availability
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Animals

• Over 90 oxygen, carbon, hydrogen, nitrogen
• 7 elements needed in fairly high amounts
  Calcium, Phosphorus, Potassium, Sulfur, Sodium,
  Chlorine, Magnesium

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Plants

• Macronutrients, micronutrients
• Extensive root systems for uptake
• Symbiotic associations to increase nutrient
  uptake (mycorrhizae) with fungi

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Other abiotic factors

• Oxygen
• Rarely limiting for plants (except those living
  in water-saturated soilsspecialized structures)
• Animalsusually have ample amounts
• Some microbes cannot tolerate oxygen
• pH
• Becoming an increasing problem with acid rains