Biology 1001A Lecture 22: LEC 22 - Arms Race.pdf
11 Feb 2014
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Document Summary
Factors influencing why some pathogens (disease-causing organisms) evolve towards greater virulence (harmfulness) If a pathogen relies on a healthy, mobile host for its spread, natural selection will favour the pathogens that do not harm their host as much. If a pathogen does not require a host to be healthy in order to spread, the pathogens that are the most exploitative for their own reproductive gains will be favoured. Mode of pathogen transmission is a factor influencing virulence. How reducing a pathogen"s opportunity for water-borne and vector- borne transmission is predicted to affect its virulence. Virus will need to rely more on direct-contact transmission. This forces the virus to evolve to become less virulent, so the host can stay alive for longer to pass on. A virulent organism causes a high proportion of people to be symptomatic and get antibiotics, which creates a high selection pressure favouring antibiotic resistance.
