280 likes | 2.3k Views
Macro-climate. Radiation, wind, precipitation, Coriolis force Effects of latitude, land & water, maritime climate, topography, etc. Rainshadow effect Major biome: desert, grassland, forest, taiga, tundra. What aspect of environmental factors is relevant?.
E N D
Macro-climate • Radiation, wind, precipitation, Coriolis force • Effects of latitude, land & water, maritime climate, topography, etc. • Rainshadow effect • Major biome: desert, grassland, forest, taiga, tundra
What aspect of environmental factors is relevant? • Maximum, minimum, averages, or the level of variability? synergistic effect? Micro-climate • thermal profile Aquatic ecosystem • light, thermocline, salinity, etc.
Physical resources and limiting factors • Range of the optimum • Liebig's law of minimum • Shelford's law of tolerance • Limiting factors
Effects of abiotic factors on distribution and abundance • Temperature - treeline and coral bleaching • Water and salinity - fog belt and tidal flooding • Nutrient - lemming cycle
Phenotypic plasticity-- environmentally induced phenotypic variation • Acclimation (vs. acclimatization) -- physiological adjustment to a changed environment
Principle of allocation: trade-offs in allocating time, energy, and other resources among various conflicting demands • Homeostasis--Maintenance of relative constant internal conditions in the face of a varying external environment • Adaptation to heat, cold, dry, wet, pressure, low oxygen supply, etc.
Principle of heat transfer Hs =Hm± Hcd± Hcv± Hr±He • Hs = heat storage by the organism • Hm = metabolic heat production (always + for a living organism) • Hcd, cv = conductive (and convective) heat exchange • Hr = radiation heat exchange • He = evaporate heat exchange
Temperature regulation in plants • Desert plant – ↓ heating by conduction, ↓ rates of radiative heating, ↑rates of convective cooling Hs =Hcd± Hcv± Hr • Foliage far enough above the ground, small leaves, open growth form, reflective surface or dense hair, changing orientation of leaves and stems
Arctic and alpine plant – ↑ rates of radiative heating, ↓ rates of convective cooling Hs = Hcd± Hcv± Hr Dark pigment, cushion growth form, hug the ground, change orientation • Tropical alpine plant – little annual but much daily temperature fluctuation
Giant rosette growth form retain dead leaves dense and thick pubescence retaining large amount of water to store heat close over the apical buds at night
ectotherm vs. endotherm • poikilotherm vs. homeotherm E = cm0.67 • Body mass ~ metabolic rate ~ food habits ~ foraging behavior ~ home range ~ social organization • morphological, physiological, behavioral specialization
Morphological • Bergman's rule, Allen's rule, pigmentation, fur, blubber, … • Behavioral • Basking, hiding, shivering, huddle, … • Physiological • Hypo-, hyper-thermia, countercurrent heat exchange, torpor…
Other factors • Moisture, nutrient, light, pH, soil, etc. • Tolerance of pollution
Fire • Types of fire: surface, ground, crown • Effect of fire • removal of plant cover • removal of litter • effects on minerals • effects on animals
Effect of typhoon • Responses to climatic changes • Ecological indicators
Distribution of snail and ground temperature
Herbivory and plant defenses • morphological defenses • chemical defenses • associational resistance • enemies hypothesis • resource concentration hypothesis
Effects of herbivory • Individual, population, communities, types of animals, productivity • Direct effect: survival, fecundity, and growth • Indirect effect: changes in competition between species and microclimate
At ecosystem level • Structure and plant composition • Redistribution of nutrient through droppings • erosion
Antipredator • Individual strategies • Hiding • Making prey location more difficult, e.g. freezing, camouflage, mimicry (Batesian vs. Mullerian), removing evidence • Making predator hesitate • Making capture more difficult, e.g. vigilance, stotting, fleeing, misdirecting
Fight back: physical resistance or chemical warfare • Cooperative defense • increase vigilance • selfish herd • dilution effect • group mobbing • Alarm call
Optimal theory • The theory used to generate hypotheses about the adaptive value of characteristics which analyzes the costs and benefits of alternative decisions in terms of their fitness payoffs • Behavioral strategies be analyzed in terms of cost and benefit in affecting Darwinian fitness (survival and reproduction)
Selecting what to eat (optimal diet) • Profitability of prey = E/h • When encounter prey 1, eat prey 1. • When encounter prey 2, eat prey 2 • if gain from eating prey 2 > gain from rejecting prey 2 and searching for another prey 1 E1/ h1 > E2/ h2, eat E2 if E2 / h2 > E1/(S1 + h1) or S1> (E1h2 / E2) - h1
Prediction • Predator should be either a specialist or generalist. • The decision of specializing depends on S1 (or the availability of prey 1) • The switch should be sudden • Examples: bluegill sunfish, great tit, crows, oystercatchers, etc.