1. SPECIES INTERACTION & COMMUNITY DISTURBANCE
NOTES ECOLOGY
SPECIES INTERACTION & COMMUNITY DISTURBANCE

2. I. Populations in Communities INTERACT
Competition: struggle for resources between living things
1. Example:
a. Interspecific competition: competition
between species that depend on the
same limited resource
2. Competitive exclusion is when 2 species are
so similar in their requirements that the same
resource limits both populations’ growth. One
species may succeed OVER the other one and
take away all the resource.

4. Niche: unique living arrangement of an organism defined by its habitat, food sources, time of day it is most active, and other factors
a. Example: 2 similar lizards, one eats
on tall shrubs, other low shrubs, * if niches
are similar, may see competitive exclusion *

6. B. Predation One organism eats another Predator --> the hunter
a. Fast and strong
b. Good senses- hearing, sight, smell
c. Camouflage
d. Sharp teeth, claws

7. The Prey --> the food
a. Good eyesight,
hearing, smell
b. Camouflage
c. Fast, agile, some are
poisonous or has
spikes

8. Symbiotic Relationships
1. A close interaction between species in which
one of the species lives in or on the other
2. Parasitism: one organism benefits
(parasite) the other is harmed (host)
a. Intestinal worms and animals
3. Mutualism: both organisms benefit from
each other
a. E.coli and people; tube worms and
bacteria
4. Commensalism: + 0 Only one organism benefits
while the other is NOT harmed, or helped- rare
a. Spider crab using seaweed to cover itself to
hide from danger

9. Parasitism

10. Mutualism

11. Commensalism

12. II. Disturbances are Common in Communities
Disturbances to communities
1. Fires, volcanoes, floods, storms, droughts
2. Effects can be positive
i. Shipwreck- can be new habitat

13. ii. Forest fires- some plants sprout

14. Ecological Succession
Primary succession: process by which a community arises in a virtually lifeless area with no soil
ex: bare rock, “start from scratch”
i. bacteria, lichens --> moss --> “pioneer organism”
ii. Grasses --> shrubs --> trees

15. Secondary succession: when disturbance damages existing community but leaves the soil in tact
Ex. When a farmer ploughs down
field to dirt, then abandons it

16. CLIMAX COMMUNITY
When an ecosystem has reached a stage where it doesn’t change very much and the community is fairly stable.
This is the final step in Ecological Succession, although many communities never make it to thi step before another disturbance comes to start the process over.

17. Human Activity and Species Diversity
Human Disturbances can have a negative or positive effect on the community-- in most cases it is negative.
Examples are:
Clearing of land-- this can be done by making farms, clear cutting for lumber, building roads, buildings or parking lots.
Introduced species-- Species that are moved into an area that they do not normally grow either intentionally or unintentionally. Some of these species do not make it in their new environment but others take over the native (indigenous) species and strip the native species of their resources.