17: Parasitism & Mutualism

In what way may a parasitic host’s fitness decrease?

1) malnourished & weak

2) stunted growth

3) sterile (reproduction)

4) die from infection

parasitoidism

parasitic larvae feed on a host, eventually killing it

ex// wasp parasitizing a caterpillar

what is the distinction between an infection & disease?

infection→presence of parasites on or within host

disease→symptoms caused by a heavy load of parasites on or within host

Are all parasites pathogenic(cause disease)?

NO

endoparasite vs. ectoparasite

examples?

endoparasite→living inside host

ex// viruses & bacteria

ectoparasite→living outside host

ex// leeches or mistletoe

part-time parasite vs. full-time parasite

part-time→parasitic only during a portion of its life cycle

full-time→parasitic during entire life cycle

hemiparasite characteristics

parasitic plant obtains some but not all nutrition from its plant host

-capable of photosynthesis so its green

Holoparasite characteristics

obtains ALL nutrition from plant host

-cannot photosynthesize=never green

what is a vector ?

Example?

an organism carrying a pathogen that can be spread to another organism

ex// mosquito carrying malaria

Direct transmission vs. indirect transmission

direct→parasite transferred directly from host to host by direct contact/carrier

indirect→diff stages of life cycle are spent in diff host

-requires 1 or more hosts

ex// brainworm eaten by snails(intermediate host), then deer eats snail(deer is host)

How does a host’s population density affect transmission of parasites?

increased host density= increased transmission

Epidemic

rapid spread of parasites among hosts

Effects of High Virulence?

high mortality of hosts, reducing transmission to other hosts

Effects of Low virulence?

allows host to recover, increasing transmission to other hosts

Define Social parasitism

when one organism takes advantage of another organism’s social behavior, like raising young/building nests

Temporary Facultative Social Parasitism

parasite depends on host for only part of its life, BUT does not need host to survive

Temporary Obligatory Social Parasitism

example?

Parasite depends on host for only part of its life, & needs host to survive

ex// cowbirds lay eggs in another nest for host to raise. Once cowbird hatches, its independent Temporary Facultative Social Parasitism

Permanent Obligatory Social Parasitism

parasite depends on host for ENTIRE LIFE & NEEDS host to survive

What is the distinction between mutualism & protocooperation?

Mutualism is obligatory but protocooperation is facultative(not necessary to survive)

-protocooperation is more common

Trophic mutualism

both species obtain energy from each other

defensive mutualism

Species A provides food/shelter; Species B defends Species A from predators/parasites

Dispersive mutualism

Species A provides food; Species B disperses Species A

What type of mutualism is a lichen an example of?

trophic mutualism

What type of mutualism is zooxanthellae and cnidarian relationship?

trophic mutualism

What type of mutualism is ants & acacias/aphids relationship?

defensive mutualism

What type of mutualism is cleaning symbiosis relationship?

defensive mutualism

define zoophilly (dispersive mutualism)

animals pollinating plant flowers

Define zoochory (dispersive mutualism)

What are the 2 types?

seed dispersal by animals

1) ectozoochory→plant seeds attached externally to animals (e.g. hiking w/ Nathan at Lake Berryessa)

2) endozoochory→seeds are eaten & released in poop

What’s the main difference between commensalism & association?

commensalism is obligatory

association is facultative(not necessary for survival)

Producer-producer example of commensalism?

epiphytic plants like lichens that grow on other plants

-trees unaffected unless TOO MANY EPIPHYTES

producer-consumer example of commensalism

birds nesting in trees

consumer-consumer example of commensalism

remoras & sharks

-remoras hide under the shark for protection & remove parasites