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Flashcards in Hw 3 Deck (29)
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1

The theory of parasites negatively correlating with IQ is largely ____. Other ideas that cause lower IQs in developing nations?

Unproven

substandard diets

2

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

3

Asexual reproduction

-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

4

Sexual Reproduction

-allows organisms to reshuffle their genes
-Sexual reproduction has the advantage when disease becomes more prevalent

5

What advantage did sexual breeding topminnows have?/

lower rate of infection by parasites because they could create new genetic combos through gene reshuffling

6

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

7

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

8

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.

9

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

10

Body weight correlated strongly with _____ . Larger bird were more likely to have _____. Give a reason this might be true?

disease susceptibility

parasitic protozoan infections

bigger targets

11

Virulence

severity of disease

12

Vertical transmission

passed from parents to offspring

13

Horizontal transmission

passed between individuals in the same generation

14

In the bird study of transmission, what were the vertically and horizontally transmitted parasites?

Vertical- feather feeding lice
Horizontal- blood sucking mites

15

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

16

Lateral transmission favors ____ virulence.

high

17

The parasite is generally _____ virulent in it definitive host than its intermediate hosts.

less

18

Sexually transmitted parasites are ____ virulent than parasites not transferred this way.

less

19

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

20

Parasites induce behavior in their hosts that make them more vulnerable to _____.

predation

21

Parasitism plays a role in the maintenance of ________.

sexual reproduction

22

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

23

A few studies have indicated that strains or dif species of parasites. It is the ____ virulent that achieves the highest transmission or report benefit

most

24

Parasites ____ to a host are more virulent than parasite known long associated w/a particular species of host.

new

25

How do we know how long a parasite has associated w/host?

phylogenetic trees

26

Vertical transmission favors ____ virulence. Why?

low

this way parental generation is alive and healthy enough to produce to infect next gen

27

In lateral transmission, selection favors parasite that reproduces ____ and whose young are dispersed to _____ despite ____.

quickly

new individuals despite its effect on original host

28

Anything that compromises host survival will lead to _____. Give example. Why?

more virulence

predation pressure exists on a host, parasite will respond w/more virulence so as to reproduce more in shorter period of time

29

Why are sexually transmitted parasites less virulent than others?

1. types of parasites are more host specific
2. essentially directed all of hosts energy into production of more parasites and little to gain from hosts demise.