1. Biological Interactions
Ecology Unit

2. Niche
Defined: how an organism lives, the job it performs in the ecosystem
How the organism affects the energy flow within the ecosystem
A niche includes an organism’s:
- Physical home Temperature/Moisture Range
- Interactions with others Behavior

3. Difference Between Habitat and Niche
Habitat – where it lives
Niche – an organism’s pattern of use of a habitat
(when, where, how interacts with habitat)

4. Ways in which Populations Interact
Categories are based on whether one species benefits or harms another species
5 Major Categories of Interactions:
1. Competition 4. Mutualism
2. Predation 5. Commensalism
3. Parasitism

6. COMPETITION
Competition: happens when two species use the same resource and the resource is in short supply
Might compete for food, nesting sites, living space, light, mineral nutrients, water, mates
Each organism has less access to the resource so they are both harmed by the competition.

7. Types of Competition
1. Interspecific competition: 2 different species compete for the same resource ex. lawn: grass, dandelions compete for nutrients and water 2. Intraspecific competition: members of the same species compete

8. Competition can cause:
Niche Restriction
- The competitors will each only use part of their potential niche. They divide it up in space or time. That way they can coexist in the same area.
Competitive Exclusion
- One species out competes and eliminates the other species (will leave the area or die off)

9. Species are not competing
Species are not competing. Natural selection has favored a range of preferences and behaviors that carve up the available resources.

10. Chthamalus can survive long periods of exposure to air
Chthamalus can survive long periods of exposure to air. Semibalanus cannot.
Below the tide line, Semibalanus is fast growing and will crowd out the Chthamalus.

11. PREDATION
Predation: process by which one organism captures and feeds upon another
Predator benefits and prey is harmed
Both evolve adaptations to help them survive

12. Examples of predator and prey adaptations
Prey: defensive chemicals, camouflage
Predators: keen eyesight, traps, pack hunting,
resistant to defensive chemicals
Trap door spider African wild dogs Stone flounder
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13. Plant defenses against herbivores
Thorns, spines, prickles
Secondary compounds – defensive
chemicals that are toxic
Herbivores overcome plant defenses
Larvae may not be affected by toxic defensive chemicals
Bull Thistle
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14. Predation and Competition
Predators help to keep the population of prey species under control. Without predators, one prey species may out compete other prey species and reduce the biodiversity of an area.
So by reducing competition, predation can promote biodiversity.
Ecosystems with a greater biodiversity are more productive and more stable.

15. SYMBIOTIC SPECIES
Symbiosis: two or more species live together in a close, long-term association
May have coevolved together
Three types of Symbiosis:
Parasitism
Mutualism
Commensalism

16. PARASITISM Parasitism: parasite benefits, host is harmed
One organism lives in or on another organism
Host provides food, place to live, spreads the parasite’s offspring
Tick in dog fur Caterpillar covered with wasp pupae aphids on a plant
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17. MUTUALISM Mutualism: both participating species benefit
Example: aphids and ants
Aphids extract fluids from sugar conducting vessels of plants, make honeydew
Ants get honeydew from the aphids that they use as food. In turn, they protect the aphids.
animals.y2u.co.uk
ecolibrary.org

18. COMMENSALISM
Commensalism: one species benefits and the other is neither harmed nor helped
Example: clown fish and anemones
Anemones have stinging tentacles that can paralyze other fish. Clown fish live in the tentacles of anemones and are protected from predators. Clown fish benefit, and the anemone is neither helped nor harmed.

19. Which type of symbiotic relationship is each of the following an example of?
1. The barnacles are filter feeders and get food as the whale moves through the water. The whale is not impacted by the barnacles.

20. 2. The bee gathers pollen from the flowers to make honey
2. The bee gathers pollen from the flowers to make honey. The flowers get pollinated.

21. 3. Spanish moss is an epiphyte
3. Spanish moss is an epiphyte. It gets the water and nutrients right out of the air and from the rainfall.

22. 4. Head lice live among human hairs and feed on blood drawn from the scalp.

23. 5. The ants eat the bud leaves off of the flower and the flower is then able to open.

24. 6. Female mosquitoes eat blood for the proteins.

25. 7. This bird eats the ticks and parasites that live on the skin of the rhino.