Evolution - Evolutionary Arms Race

- garter snake eats rough skin newt - snake must evolve resistance, newt must evolve better toxin

- snakes more resistant to toxin are slower when not poisoned, therefore, comes at a cost

- possible that carnivores once pushed our own evolution making us stronger, faster, smarter

- when antibiotics stop, resistant bacteria remain and multiply. Low quality drugs and incomplete treatment courses contribute to increased resistance

- should people infected with transmissible non-curable diseases be allowed to be in the general population?

- because of global travel - all resistant bacteria will eventually reach other areas. Already showing up in North American populations

- 2-3 million die each year from TB

- dozens of other bacteria are evolving resistance

- over of all prescriptions are unnecessary or inappropriate



- if close contact is required for transmission then an organism usually is not very harmful because it needs healthy hosts to move around so it can reach its next host. If too dangerous, people are immobile and bacteria must be transmitted some other way (water, insects, food).

- poor water supply favored increased toxin in cholera because didn't need healthy hosts. Improved water quality forced the bacteria to evolve less potent cholera toxin because if people were too sick, wouldn't be transmitted. Was observed in Latin America cholera outbreaks



- wild cats seem resistant to FIV.

- 1M YA the cats were decimated by FIV but survivors were resistant. Now, have evolved to one another. The cats carry the virus but aren't affected by it.

- found a mutation which eliminated a receptor on cells found in 10% of European Caucasians but absent in Africans and Asians. Survivors of the Black Death may have passed on mutations giving resistance to HIV

- cooperation also plays a powerful force in evolution especially mutualistic symbiosis.

- 50-60 M YA leaf cutter ants ate fungus because toxins in plants so couldn't eat them. The ants carry mats of bacteria which produce antibiotics that kill mold which destroys fungus in the garden. Bacteria evolved along with the mold.



- microbes in the environment teach the immune system how to deal with harmless antigens.

- removal of these microbes has increased rates of allergies and asthma - strong links have been demonstrated

- we evolved in a world surrounded by microbes and have developed immunity

- most are neutral or even beneficial - few are dangerous

- can probably use evolution to shape the future.