PSYO 2160 Lecture Notes - Lecture 12: Evolutionary Arms Race, Red Queen Hypothesis, Parasitic Castration
3 May 2018
School
Department
Course
Professor
Parasitism
October 28-30, 2015
Symbiotic Relationships:
• Parasitism: non mutualistic symbiotic relationship
o Parasite benefits at cost to host
• Mutualism/cooperation: both benefit
• Commensalism: one organism benefits without the other affecting it
Parasitism:
• Reduce host fitness by exploiting hosts’ resources to increase their own fitness
• Parasitoid: sterilizes, kills and consumes the host
Parasites:
• Ectoparasites: live outside host (lice/fleas)
• Endoparasites:
o Intercellular (ex. Intestinal parasites) – within body
o Intracellular (ex. Virus, bacteria) – within cells
• Mesoparasites
• Obligate parasite (holoparasite): requires a host to complete life cycle
o Definitive host – reproduction occurs inside host
o Intermediate host -
• Facultative parasite: does not require host to complete life cycle
• Parasites are incredibly specialized
o E.g. tapeworms obtain resources from absorbing nutrients through small
hairs and live in intestines to move through body and swim
o E.g. hookworms have modified heads to suck blood from intestines by
latching on
How are Parasites so Prolific?
• Parasites evolve to outcompete hosts’ defense
o Evolutionary arms race and Red Queen Hypothesis
• Parasites have much smaller generation times compared to their host to win the
evolutionary arms race
Parasites Can:
• Divert resources
• Parasitic castration
• Manipulate Behaviour
Pork Tapeworm:
• Definitive host: humans
• Intermediate host: pigs
• Infection through contaminated pork
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Symbiotic relationships: parasitism: non mutualistic symbiotic relationship, parasite benefits at cost to host, mutualism/cooperation: both benefit, commensalism: one organism benefits without the other affecting it. Parasitism: reduce host fitness by exploiting hosts" resources to increase their own fitness, parasitoid: sterilizes, kills and consumes the host. Parasites: ectoparasites: live outside host (lice/fleas, endoparasites, intercellular (ex. Intestinal parasites) within body: intracellular (ex. How are parasites so prolific: parasites evolve to outcompete hosts" defense, evolutionary arms race and red queen hypothesis, parasites have much smaller generation times compared to their host to win the evolutionary arms race. Parasites can: divert resources, parasitic castration, manipulate behaviour. Behaviour manipulation: hypothesis: a parasite can alter host behaviour to increase its own transmission efficiency, indirect (ex. Infected men showed lower superego strength, higher vilagence. Infected women showed a higher warmth and higher superego: opposite behaviour in sexes correlation.
