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9 Cards in this Set
- Front
- Back
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Thermoregulation in artic plants adaptations |
Arctic Strategy • Short dense - cushion • Dark pigment • Perpendicular leaves
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Thermoregulation in desert plants adaptations |
Desert Strategy • Tall and branchy – hairy/pubescent • Light pigment • Parallel leaves |
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Thermal Neutral Zone (TNZ) |
Temp. range where metabolic rate is constant (homeotherms) |
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Strategies for coping with temps outside tolerance range? |
1) Death 2) Migration 3) Resistance |
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Strategies for coping with temps outside tolerance range? Death |
Invest minimal energy in maintenance and maximal energy in reproduction – Complete life cycle prior to severe temperature of winters – Overwinter as seeds or eggs – E.g., plants, insects |
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Strategies for coping with temps outside tolerance range? Migration |
Often between breeding and wintering grounds • Costs – predation, energy • Often along specific pathways between sites • E.g., Birds, reptiles, mammals, insects, fish |
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Strategies for coping with temps outside tolerance range? Resistance |
• Use specialized traits to survive extremes– Fur, fat, feathers • Insulation – reduces heat loss – Acclimation: seasonal tolerance of cold temperatures– Inactivity/Avoidance • Burrows/cavities • Acquire freeze tolerance Reduce metabolic rate– Food availability decline – less energy available for processes Reduce maintenance costs by reducing metabolic rate…but expensive to come out of!– Hypothermia: • Torpor = <1 day (“daily hibernation”) • Hibernation (winter; estivation in summer) = multiday torpor |
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Cold temperature tree adaptations |
• Ice crystals forming in cytoplasm is fatal • Freezing avoidance mechanisms: 1. Antifreeze 2. Insulation 3. Extracellular freezing 4. Supercooling• Usually several of these in combination provide freezing tolerance |
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What Limits Northern Limit of Trees? |
1) Excessively cold winter temperatures (cell sap freezes if above the snow) 2) Growing season too short for trees to produce mature seed 3) Permafrost – roots cannot reach deep enough to support the tree 4) Abrasion by wind-driven ice and snow – removes cuticle and bark, desiccates leaves |
