Science Starter: How do Fossil Records show evidence for Evolution?

Bad Germs – Good evidence of Natural Selection pneumoniaStaph infection TB-tuberculosis

Antibiotics – The Biggest Advance in Medicine of the 20 th Century or is it?

Streptococcus pneumoniaeis Bacteria and Antibiotic Resistance Streptococcus pneumoniaeis a leading cause of serious illness among young children worldwide and is the most frequent cause of pneumonia, bacteremia, sinusitis, and acute otitis media (AOM). Widespread overuse of antibiotics contributes to emerging drug resistance.

Bacillus anthracis Mycobacterium tuberculosis Salmonella Typhi. Some Other Bad Germs Methicillin-resistant Staphylococcus aureus

How is that an example of Natural Selection?

Natural Selection in Action ① Microbes – bacteria, some fungi, viruses – have a short generation time: bacteria 20 min ② Mutation Rates are much higher ③ 1+2 = greater genetic variation upon which natural selection can act ④ Selective pressure or survival of the fittest – use of drugs or vaccines to kill the microbes

Those that adapt will survive and become resistant to the drugs we use The adapted microbes will reproduce, the others will be dead – so adapted ones (drug- resistant ones) are the only ones left standing

Flu Virus – a special Challenge Viruses adapt to US – to our defenses Its genes mutate often – produce different proteins When two different viruses infect he same cell, they can swap genes Our Immune system recognizes proteins on the surface of the virus – so viruses change these surface protein constantly to escape detection

Flu Vaccines Made each year differently to match a few different strains of flu virus (usually last years strains) How effective the vaccine is depends on how well it matches this years flu virus strains – how similar the vaccine is to the current virus

During years when it is not well matched to circulating viruses, it’s possible that no benefit from flu vaccination may be observed. During years when there is a good match, it’s possible to measure substantial benefits from vaccination in terms of preventing flu illness. A good match is difficult to achieve, because the virus changes so frequently How effective is the flu vaccine?