Extremes with lower metabolic rate can live on

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Unformatted text preview: rce scarcity, rather than temp. extremes (with lower metabolic rate, can live on reserves) Performance Different processes have different tolerances Reproduction Growth Survival Low environmental variable High Successful reproduction / population maintenance at narrower ranges than survival & growth Dealing with environmental variability Ex: ways of regulating body temperature not regulate regulate homos (greek) “same” Poikilotherm poikilo (greek) “varying” basking, moving between shade/sun, active at certain times of day environment, behavior, &c. internal metabolism Ectotherm Endotherm ecto (greek) “outside” heat used to elevate body temp comes from outside internal metabolism, ≈ constant temperature Homeotherm Dealing with high temperatures: example of convergence reduce sun exposure, increase cooling Temperature regulation by skunk cabbage, WI starch stores in taproot 20 rate of O2 consumption elevated metabolic rate in spadix, heat melts snow 15 J 10 5 J JJ J J J J J J J J J J J J 0 0 5 10 15 air temperature (C) 20 modulation of metabolic rate according to air temp.? Is this veg an endotherm? Temperature regulation in hawkmoths flight muscles: warm thorax => overheating thermoregulate: transfer heat to abdomen by hemolymph, radiate from abdomen experiment to test hypothesis; data: change in abdomen temperature Apply heat to thorax Live experiment: block hemolymph flow to abdomen Flying thorax stable, abdomen heats up Blocked Dead Control thorax overheats, abdomen stable; moth stops flying Thermoregulation by evaporation experiment: progressively increase air temp. result: increased in rate of water loss experiment: step change in air humidity (5 -> 100 -> 5%) result: increased body temp. Dealing with low temperatures: ice crystals damage cell structure when cells freeze maintain body temp. above freezing use metabolism to generate heat Endotherms, Homeotherms prevent freezing antifreeze-like compounds (e.g. antarctic fish, some insects) tolerate freezing Insulation: Fur, Blubber surviving with 50% or more of total body water frozen e.g., wood frogs http://videos.howstuffworks.com/tlc/28588understanding-frozen-wood-frogs-video.htm...
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