Mutualism and Paracitism Flashcards
exploitation, and what constitutes as it
predation, herbivory, paracitism
one benefits one is harmed
Mutualism
a mutually beneficial interaction between individuals of two or more species
Commensalism
an interaction in which individuals of one species benefit while individuals of the other species do not benefit nor are harmed (i.e., neutral)
facilitation
a positive interaction
Symbiosis
a relationship where individuals live in close physical contact
* Importantly, this can be: +/+, +/0, or +/-
Symbiotic relationships are not always
mutualistic (vice versa)
Symbiosis is characterized as
a close physical, interdependent association between >two organisms
Non-symbiotic mutualisms
- Pollination
- Birds cleaning ungulates
- Cleaner fish
Interactions between species may fall somewhere on the continuum of:
++, +0, +-
meaning Biology/evolution/etc. is rarely black and white
what percent of land plants rely on mycorrhizal relationships
what do relationships do
about 80% of land plants rely on mycorrhizal relationships with fungi to provide inorganic compounds
the evolution of the eukaryotic cell is called
what type of interaction?
symbiogenesis theory
mutualism
barnacles and whales are an example of
commensalism
tick and host example of
parasitism
Obligate mutualism
Not optional
occurring by necessity
Dependance on specific partners
Facultative Mutualism
occurring optionally
No dependance on specific partners
(low risk of extinction if a partner
goes extinct)
Fig-wasp what obligate or facultive
- Neither species can exist
without the other
–> obligate
Nurse plant in the desert facultative or obligative
Nurse plants in the desert
* Soil beneath an adult is cool and
moist – good for seedlings
-Facultative
beacuse mfs can live w/o
Anemones Clownfish type mutualism
Anemones provide fish with
protection from predators
* Due to the presence of stinging cells
* Clownfish defends anemones from
butterfly fish
Service-service relationships–> rarest form
Acacia trees and ants what type of mutualistic relationshoip
Ants protect acacias from herbivores
* Ants also trim back other vegetation
that would otherwise shade the
acacias
* Acacias provide shelter; ants nest
inside the thorns
* Ants also eat on food-bodies produced by the
plant, introducing a service-resource component
to the interaction
-service service relationship
Mycorrhiza is what type of mutualist relationship?
resource - resource
Service-resource relationships and examples
-pollination
-cleaning symbiosis
-Zoochory
most common form
Plant species that rely on animals for pollen dispersal often have
very specific pollinators that they have co-evolved with.
Ophrys apifera
A flower that resembles a female bee
Sexually deceptive pollination
Plant also emits chemicals that mimic females bees.
* Males are attracted and attempt to copulate with it
Pollinators provide
ecosystem services
Zooxanthellae
Single-celled dinoflagellate / algae that photosynthesize inside of coral tissue
Zooxanthellae relationship w coral
- Provide glucose, glycerol, and amino acids to the coral in exchange for protection
- Help remove coral’s waste (Ammonia)
- They also give coral their coloration
Lichen fungal symbiosis w cyanobac/ algae
The body of a lichen consists of fungal filaments (hyphae) surrounding cells of
green algae and/or blue-green cyanobacteria.
* Fungus receive nutrients obtained via photosynthesis
* Algae receive food/protection/stability from the fungus
Trophic mutualisms
mutualist receives energy/nutrients
from its partner
* Leaf-cutter ants and fungus
* Mycorrhizae
* Coral/alga
Habitat mutualisms
One partner provides the other with
shelter, living space, or favorable habitat
* Pistol shrimp dig burrows that that they share with goby fish - goby gets a refuge and in turn serves as a “seeing eye fish” for the nearly blind shrimp
Many mutualisms are thought to have evolved from
antagonistic interactions
virulence theory
a model which predicts reduces antagonism, perhaps in the direction of mutualism, in parasitism interactions were host fidelity is high and alterative hosts are not an abundant option
E.g., Wolbachia (bacteria) which are vertically transmitted with Drosophila simulans what happened
Basic idea is that because they are maternally transmitted, parasites may evolve towards a more mutualistic relationship with their host
Each partner should act in such a manner that
serves its own ecological and evolutionary interests
Although both partners in a mutualism benefit
there are also costs
sometimes the cost is a reward for the service
Cheaters
individuals who does not cooperate (or cooperates less than their fair share) and/or exploit their partners while gaining a benefit at their expense
what are the risks to cheating
may be penalties imposed by exploited individual
why does mutualism evolve?
what happens if it goes too far?
net effect is advantageous to both partners
disadvantageous it would probably break
down or become parasitism
Mutualisms are not
friendly interactions among species
reciproical parasitism
RECIPROICAL PARASITISM
Arbuscular mycorrhizal (AM) fungi
Penetrate the cortical cells of plant roots,
forming a branched network called an
arbuscule
* in 80% of plant species
Ectomycorrhizal (EM) fungi
do not penetrate cortical cells
Mycorrhizal fungi relationships exist when
associations are mutualistic when Net Costs < Net Benefits
AMF are more mutualistic
when grown in nutrient poor soil
plant- AMF relationships form a continuum
from mutualistic to parasitic interactions.
Parasitism is a form of
exploitation
what is different between predator prey and parasite host
a parasite forms an intricate and long-term
relationship with the host – something that
herbivores & predators do not do.
like mutualism, parasitism
may either be Obligate (Not optional) or Facultative (optional)
Endoparasites
(living inside the host
Ectoparasites
living outside the host (e.g., skin))
Mesoparasite
enter through an opening of a host’s body and
remain partly embedded
Brood parasites
lay egg in other species nest for example
cuck them
Kleptoparasites
stealing food gathered from a host
Sexual parasites
anglerfish males are tiny compared to
the size of females
Vector-transmitted parasites vs Directly-transmitted parasites
requiring a third party, a vector
not requiring a vector(lice)
Parasitoids
insects that eventually kill their hosts (wasps, flies, etc.)
Trophically-transmitted
requiring the host to consume them (e.g., roundworms,
liver fluke)
* These parasites often alter the behaviour of their hosts
Red-Queen Hypothesis
-A hypothesis describing how reciprocal evolutionary effects among species leads to coevolution\
-Species (or populations) must continually evolve new adaptations in response to evolutionary changes in other organisms to avoid extinction
Has been adapted to explain the evolution of
many phenomena (Sex, Mating systems ,Pathogen virulence Maintenance of genetic diversity)
