Flashcards in Hw 3 Deck (29)
The theory of parasites negatively correlating with IQ is largely ____. Other ideas that cause lower IQs in developing nations?
Transmission cycle of liver fluke
1) Ants consume slime of a passing snail
2) Slime is loaded with the eggs of a parasite called the Liver Fluke (flat worm)
3) Live fluke burrows in an ants brain to carry them to their next host
4) Liver fluke can switch the ants behavior on and off causing the infected ants to place themselves in easy to eat positions
5) Cows ingest fluke larvae
6)worms burrow out of the stomach into the liver where they develop into adults and eat liver tissue
7) Worms then lay eggs that are excreted from the liver into the bile duct and produced in the feces
-produces more offspring over time
-always expected to have the advantage over sexual reproduction if all things are equal
-Asexual reproduction wins when disease or parasite are not of great issue
-allows organisms to reshuffle their genes
-Sexual reproduction has the advantage when disease becomes more prevalent
What advantage did sexual breeding topminnows have?/
lower rate of infection by parasites because they could create new genetic combos through gene reshuffling
Modeling predicts that sexual repro wins under conditions of high _____ and high ____. Why
probably of parasite transmission; effect of parasite on biology or host
sexual reproduction is only worth it when probability of being negatively affected by parasites
It was hypothesized that organisms with more high developed epidemic traits will be exposed to ____. Species with more sexual sexual selection____ at risk for damaging parasites.
more types of parasites; more
How did researchers test the epidemic trait/parasite risk hypothesis with birds?
analyzed blood smears for parasites and rate species on showiness and song. Incidences of disease were compared w/these factors.
What were the results of parasite/showiness study? Why did sexual dimorphism decline on islands?
positive relationships between diseases present and epidemic traits. Female brightness had the lowest coefficient compared to male brightness and song.
not as many parasites on islands
Body weight correlated strongly with _____ . Larger bird were more likely to have _____. Give a reason this might be true?
parasitic protozoan infections
severity of disease
passed from parents to offspring
passed between individuals in the same generation
In the bird study of transmission, what were the vertically and horizontally transmitted parasites?
Vertical- feather feeding lice
Horizontal- blood sucking mites
How did mode of transmission affects birds in the study?
Vertically transmitted lice- no significant effect on bird survival or their offspring
Horizontally transmitted mites: lower hatching success, lower post fledgling survival, fewer surviving offspring. Did not affect adult bird survival or body
Lateral transmission favors ____ virulence.
The parasite is generally _____ virulent in it definitive host than its intermediate hosts.
Sexually transmitted parasites are ____ virulent than parasites not transferred this way.
Parasite effects used to be believed to be due to _____. it is now known they _____.
nutritional demands and drain on potential energy
go beyond this
Parasites induce behavior in their hosts that make them more vulnerable to _____.
Parasitism plays a role in the maintenance of ________.
most modern theories of sexual dimorphism treat flashy non combat displays and morphology of males as advertisements that they are ____.
parasite free or can tolerate parasites so as to grow ornaments. Advertising good genes
A few studies have indicated that strains or dif species of parasites. It is the ____ virulent that achieves the highest transmission or report benefit
Parasites ____ to a host are more virulent than parasite known long associated w/a particular species of host.
How do we know how long a parasite has associated w/host?
Vertical transmission favors ____ virulence. Why?
this way parental generation is alive and healthy enough to produce to infect next gen
In lateral transmission, selection favors parasite that reproduces ____ and whose young are dispersed to _____ despite ____.
new individuals despite its effect on original host
Anything that compromises host survival will lead to _____. Give example. Why?
predation pressure exists on a host, parasite will respond w/more virulence so as to reproduce more in shorter period of time