E. INTERACTIONS WITHIN COMMUNITIES

1. Interspecific competition

a. 2 or more species struggling for the same resource

b. both species will lose

c. eg.

2. Predation a. one species kills and eats another

b. the predator gains but the prey loses c. but if the predator eats too many prey, then

the prey runs out & predator also loses

n

u

m

b

e

r time

PREY

PREDATOR

d. note: there is always more of the prey the two cycles are out of synch as there is a delay in the effect

as predator #’s increase, prey #’s fall;

as prey #’s fall, predator #’s fall

3. Defense mechanisms a. camouflage – don’t get seen by predator OR prey

eg. rabbit OR bobcat

b. toxins – produce or accumulated

eg. Monarch butterfly

eg. sea slug

c. mimicry - pretend to be toxic

eg. Viceroy butterflyNot toxic, but appears to be

eg. Monarch butterflyWings are toxic.

d. distractors – trick the predator in some way

large eyespots distract the predator

4. Symbiosis

a. mutualism - both gain

eg. oxpecker & giraffe

Oxpecker gets to eat insects and giraffe gets rid of parasites

b. commensalism - one gains, one unaffected

eg. algae on back of turtle

Algae gets a sunny perch and turtle which is already green, gets no benefit, nor any harm.

c. parasitism - one gains, one loses

eg. mosquito and you

The mosquito gets blood for its eggs and you lose blood and may get a disease.

what type of defense is this?

rattlesnake

hoverfly

The rattlesnake has to warn off animals so it does not have to use its TOXIN.

The bee has warning colours as its sting is ‘toxic’. But the hoverfly has no sting and so it is a MIMIC.

Questions D from pg 8.