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Physiological Adaptations: Life's Survival Strategies

Analysis of how organisms like Drosophila and E. coli adapt to physical variables like temperature, osmotic stress, water availability, and food scarcity through generations. Discover the impact on their survival tactics and niche shifts in different environments.

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Physiological Adaptations: Life's Survival Strategies

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  1. Physiological Adaptation Life in the Lab

  2. Physical Variables • Temperature • Drosophila • The knock-down time increased fourfold after 18 generations • Also saw increases in flight time • There was a shift in the niche • E. coli • It is possible to adapt E.coli to specific temperatures and have them out compete their ancestor • At almost all temperatures, specializing in one temperature did not narrow the range of temperatures at which the bacteria could live

  3. Physical Variables • Osmotic Stress • Marine fish • Originally hypo-osmotic relative to environment and have chloride cells in their gills that excrete Na+ and Cl- • Guppies (a fresh water fish) have been evolved in high saline environments • Show an increase in the number of chloride cells

  4. Physical Variables • Water • Used to define where life can exist • Drosophila • Can be rapidly adapted to survive in dry environments • Surviving lines tend to have increased body mass, carbohydrate levels and water contents • Females are more resistant than males

  5. Resource Variable • Food – Starvation Stress • Drosophila • When selection took place with adults they increased resistance after about 20 generations • When selection took place with larva there it took longer to obtain the same resistance • Adaptations included increased fat storage and lowered metabolism • Flies will die of desiccation before they die of starvation

  6. Resource Variables • Food • E. Coli • When grown in low nutrient media they evolved to deal with the starvation mode • Some evidence shows they developed into cannibals eating their competitors • Some have evolved the ability to come out of the dormant mode quicker beating those that are slower to the food

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