TOPIC 22: SYMBIOSIS Flashcards
What is important in community ecology?
Understanding interactions between organisms is important in Community Ecology
- interactions influence the presence, and abundance of species
What is symbiosis?
is an intimate relationship between two organisms. (“together living”); interaction between 2 species where one species benefits and one species does not survive without the other species, other species either benefits, detrimental or no effect
- One or both species depends on the other for survival
- This relationship can either be positive, negative or neutral for those involved.; ALWAYS POSITIVE FOR ONE SPECIES
What are the 3 types of symbiosis?
o Parasitic= parasite (+), host (-)
o Mutualism= = +/+= BOTH species have a positive interaction
o Commensalism = commensal (+); depends on host for its survival , host(0); unaffected by interaction
PATTERN IS THAT ONE IS ALWAYS POSITIVE
Parasitism
is a relationship between organisms of different species
* One species benefits from the close association
* The other is harmed
How do parasites increase their fitness?
by exploiting a host organism
- Food, habitat (safe), dispersal
- Both the parasite and host can regulate each other’s population growth (LotkaVolterra)
- parasite= pseudopredator; more parasites means host pop. decreases less pop for parasites means parasite pop decreases gives host chance to grow
give 2 examples of a parasitic relationship
a. fleas are parasites that live on the host
ex- witches broom plant that grows into bark outcompetes plant drains resources
Do parasites kill their hosts why or why not?
Parasites tend to not kill their hosts
1. no advantage to killing its host because host provides habitat and food source
(dead host → dead parasite); viruses like ebola can kill
- Host uses energy to defend against the parasite – redirects energy from growth and reproduction
What is the result of parasites not killing their host? (EXAM)
- Decreased reproductive success
* Redirect energy to growth and survival to fight off parasite
* Reduced expression of 2º sexual characteristics (attractiveness); something that has parasites appears unattractive so female wont choose it affects its fitness - Increased mortality due to secondary infections; parasite infects host without thinking of what other parasite is infecting it
- Increased mortality due to increased susceptibility to predation
* Decreased ability to escape predators; parasite might make prey less healthy less able to escape predator
- More conspicuous to predators via abnormal behaviour; make host obvious so predator can consume it
ex- guppie has translucent skin but parasite makes it more visible; parasite wants to be eaten so it can enter host it wants to enter which is predator
What can parasites be classified as?
Microparasites; need microscope to see them
* Includes viruses, bacteria and fungi
* Small size and develop rapidly
- MORE LIKELY TO KILL HOST; better dispersal get into another host and multiply
Macroparasites
* Flatworms, roundworms, lice, fleas, ticks, rusts and smuts
* Large size and develop slowly;
do not want to kill host b/c need it to complete life cycle
Ectoparasites
live on the skin, within the hair, or feathers of their host
Endoparasites
live within the host’s body, in the heart, brain, spinal cord, nasal
tracts, lungs, digestive tract or circulatory system
ex- tapeworm attaches in tract and grows
plasmodium is a microparasite; intracellular blood parasite, goes into RBC and bursts out and infects more RBC
What is Direct Transmission?
Parasite is transferred from one host to another directly
* Influenza, smallpox, sexually transmitted diseases
* Fleas, ticks, lice, mites, round worms
* Direct physical contact, water or air
(* just means from same host to to same host)
What is Indirect Transmission?
Parasite is transferred from one host to an intermediate (vector) and then to another
host
* Malaria, protozoan parasite
* Can result in some very complex life cycles
Mutualism
a relationship between two species where both species benefit (+/+)
* Individuals of both species enhance their survival, growth, and/or
reproduction
* Reciprocal exploitation vs Cooperative effort
Eg. Corals – mutualism between cnidarian polyp and photosynthetic algae
Explain the difference between Reciprocal exploitation vs Cooperative effort? (EXAM)
Reciprocal; bee might’ve been exploiting flower for food and then the flowers exploits bee for pollination services ( both exploiting each other)
cooperation; both original species (lichen; algae and fungus) thru combined efforts are able to exploit environments they previously were not able to-> algae produces food thru photosynthesis and fungus provides moist environment both benefit and allows both of them to exist in an area they weren’t able to before
