EEB214H1 Lecture 21: Human Evolution
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Department
Ecology & Evolutionary Biology
Course
EEB214H1
Professor
Jennifer Carpenter
Semester
Winter

Description
EEB214 Lecture 21 Pathogens have many of the same evolutionary patterns we’ve talked about before If there is heterogeneity in the host it will select for: sex • when the environment varies, sex is selected for because sex helps make new gene environments • snail example: variation with how much infection • these bacteria has to deal with different genotype • organisms that can have sex will have it at higher rate so there is sex for variation • in a population that is mixed heterogeneous we expect diseases to evolve • but similar population can select for increase virulence • If there is a competition within a host it will select for o whichever one that is more effective in exploiting the niche is going to spread o resources in the host are limited o e.g., HIV [affects white blood cells] o but only so many white blood cells so if someone’s infected with 2 strains and one grows faster, it can use up that white blood cells o selection makes it more efficient with the resources they have • If they make more virus particles, they’re more likely to spread and more likely to breathe in the more common one • If there are closely related pathogen strains living together o kin selection o if kin selection is acting and these guys are living in a host with another relative, they won’t use up the host because they want to increase their fitness [grow together] o e.g., Malaria in mice • Hygiene hypothesis states that lack of exposure to pathogens has caused our immune systems to become out of balance, causing autoimmune diseases o we are involve to be sick, now we aren’t which cause parasites • Type I diabetes is caused by destruction of insulin producing cells by the immune system o pancreas being attacked by own body o places where there are other infectious disease, less likely to have type I diabetes • If your immune system gets lower, there’s other things that could infect you • Guys with higher immune activity will do better • When immune system gets bored it will start attacking things o happening because we evolve where we always had tapeworms o we have evolve where our genome expected to have tape worm lowering our immune system but now we don’t have it anymore so the immune system attacks our own body o hence is why people suggest that being too clean is affecting our immune system • Multiple sclerosis is characterized by damage to nerve tissue by the immune system o over 4.5 years patients infected with worms did not get worse while uninfected patients did
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