hilalsultanpara

A weathering

B high pressures

C high temperatures

1. E. coli O157:H7 and E. coli O26:H11 are two different serotypes of EHEC. Although they share the characteristic of being able to cause hemorrhagic colitis and HUS, they are otherwise only distantly related to one another (no more closely related on average than to any other E. coli strain) (10 pts.).

a. What genetic information have each of these serotypes acquired that make them EHEC?

b. What is the main evidence supporting the hypothesis that each of these serotypes evolved from a distinct progenitor that belonged to the EPEC group of diarrheagenic E. coli?

c. Is your answer to B an example of parallel, convergent, or divergent evolution? Please explain your answer.