Lecture 3 – Sept 20th – Coping with Environmental Variation.docx

Lecture 3 – Sept 20th – Coping with Environmental Variation.docx

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Lecture 3 – Sept 20 th – Coping with Environmental Variation: Temp & Water Ecological success 1) Availability of energy and resources— impacts growth and reproduction. 2) Extreme conditions can exceed tolerance limits and impact survival. energy supply can influence an organism’s ability to tolerate environmental extremes. Geographic distribution of species related to disturbance & competition (+ env, physiological etc) Stress Response > Acclimatization > Adaptation *understand graph/be able to draw Acclimatization and adaptation require investments of energy and resources, representing possible trade-offs with other functions that can also affect survival and reproduction. Plants = good indicators of physical env Ex – aspen trees low temp, drought Physiological Ecologist = study of interactions bw org & physical env that influence their survival/persistence vs ecologist – doesn’t deal w/ physiology Optimum conditions for physiological processes Stress = environmental change results in decreased rates of physiological processes, lowering the potential for survival, growth, or reproduction. Acclimatization : Adjusting to stress through behavior or physiology. usually a short-term, reversible process happens in individuals Acclimatization to high elevations involves higher breathing rates, greater production of red blood cells, and higher pulmonary blood pressure. Adaptation : Individuals with traits that enable them to cope with stress are favored. Over time, these genetic traits become more frequent in the population. Via natural selection, to best deal w/ stress Happens to population Evolutionary/longterm Ecotypes: Populations with adaptations to unique environments. Locally adapted Can become separate species bc population divergence & reproductive isolation Temp Variations in Biosphere Lower limits – water freezes in cells @ -2, -5 Upper limit – boiling pt (ex some archaea & bacteria @ 90) Enzymes Metabolic rxns catalyzed by enzymes (w/ narrow temp range for optimal fn) High temp = enzyme denaturing Some species produce different forms of enzymes ( isozymes ) with different temperature optima that allow acclimatization to changing conditions ex – crayfish Lipid Bilayer Low temp = lipids solidify = embedded proteins can’t fn = cells leak metabolites. Plants that thrive at low temperatures have higher proportions of unsaturated lipids (with double bonds) in their cell membranes Cryonics = preservation of bodies by freezing, in hope that they can be brought back to life in the future. example o Two frog species live in the Arctic tundra and can survive winter in a semi-frozen state. o They overwinter in shallow burrows, with no heartbeat, no blood circulation, and no breathing.
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