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Ecology Lec 5 (coping with temp & water variation) summary.docx

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Biology 2483A
Hugh Henry

Ecology Lec 5: Coping with Temperature & water variation Physical environment impacts organisms success in 2 ways: 1. Availability of energy & resources- growth & reproduction 2. Extreme conditions- may exceed tolerance The actual geographic distribution- also depends on competition, disturbance etc Plants don’t move = good environmental indicators Climate envelope- a range of conditions over which it occurs e.g Aspen tree- predicted vs actual distribution Physiological ecology: study of interactions between organisms & environments that influence their survival & persistence Physiological processes- have an optimal - Stress- deviation from optimum- reduced rate of process Acclimatization- adjusting to stress via behaviour or physiology - short term & reversible (e.g climb Mt. Everest, RBC↑, come down, RBC ↓) Adaptation- long term, natural selection causes adaptation - favourable genetic traits increase in frequency (e.g big ears selected to dissipate heat) Acclimatization & adaptation may require trade offs with other functions Ecotypes - same species but different because had adaptations to different environments - can eventually diverge- speciation Temperature- internal temp. of organism is important for survival o o - high limits (bact, archaea 90 C), lower limits- when water freezes in cells (-2 to -5 C) Endotherms- Rely on internal heat generation (birds, mammals)- more energeticallu expensive - more contrained, smaller internal temp range Ectotherms- regulate body temp through exchange with external environment - larger internal temp range Some use heat generation as a Some are hybrids of ecto & endo therms – NOT clear cut defence: bees swarm hornet, beat wings to heat kill it Enzymes- have narrow range of temp (optimum) - different optimum for different organisms - isozymes: different forms of same enzyme- switch to acclimatize to changes Cell membranes - low temp→ solidify - low temp plants – have high unsaturated lipids (Double bonds, kinks so more fluid) Ectotherms- ↑SA/V ratio = greater heat exchange, but harder to maintain internal temp - small ecto- ↑SA/V- remain at same temp as water - large ecto- ↓SA/V- maintain higher body temp - can’t gain/lose
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