1. Ecological Relationships and Succession

2. Predator/Prey
A relationship between individuals of different species in which one individual captures and eats another individual from a different species.
Hawk fish
Spider grasshopper dragonfly

3. Predator–Prey Relationships
Discuss the relationship between the hare and the lynx population size.
What does this information tell you about …….
A. the effect of size of prey populations on the number of predators?
B. the effect of predators on the populations of their prey?
What other factor would influence the size of the hare population in addition to the size of the population of lynx?

4. Mutualism Symbiotic Relationships:
close, long-term interaction between two different species
Mutualism
A symbiotic relationship between individuals of different species in which both individuals benefit from the association.
Example: Cleaner shrimp on sharks (both benefit)
Shark- cleaner fish
Bee flower pollinator

5. Commensalism
A symbiotic relationship between individuals of different species in which one individual benefits, while the other is unaffected by the association.
Example: Barnacles on whales (barnacles benefit, whales are unaffected)
Whale barnacles
Squirrel tree

6. Parasitism
A symbiotic relationship between individuals of different species in which one individual benefits, while the other is
harmed by the association.
Example: Ticks on dogs (ticks benefit, dogs are harmed)
Catepillar and wasp larvae –when larvae hatch, they eat the catapillar
Ivy on a tree (steals nutrients)

7. Niche The role or function of an organism or species in an
ecosystem, and its interrelationships with all of the abiotic and biotic factors affecting it.
Example: swamp grass is a shelter for some organisms and food for other organisms, it relies on water, soil, and sunlight to survive
Fundamental niche: the set of resources a population is theoretically capable of using under ideal conditions
Fundamental niche: the set of resources a population is theoretically capable of using under ideal conditions
Realized niche: the resources a population actually uses
The realized niche may be smaller than the fundamental niche because of interspecific interactions such as:
Competition
Predation

8. Joseph Connell's Famous Experiments
Two species of barnacles live in a stratified distribution in the intertidal region along the Scottish coast.
Observations:
Balanus is most concentrated in the lower intertidal area.
Chthamalus is most concentrated in the upper intertidal area.
The free-swimming larvae of each species can settle anywhere on the rocky shoreline, and presumably be able to grow to be an adult.
Question: why don't we see Balanus and Chthamalus growing together?
Experiment 1:
Connell removed Chthamalus from the upper area, and no Balanus replaced it.
Inference: Balanus could not survive in an area that experienced so much desiccation (due to low tides).
Conclusion: Balanus's realized niche was the same as its fundamental niche.
Experiment 2:
Connell removed Balanus from the lower area and Chthamalus replaced it.
Inference: Balanus was a more successful competitor in the lower intertidal zone.
Conclusion: the fundamental niche and realized niche for Chthamalus were not the same—its realized niche was smaller due to interspecific competition.
Conclusion: competition occurs in nature and can explain the distinction between a fundamental niche and a realized niche.

9. Inter-specific Competition
P. caudatum and P. aurelia are both species of Paramecium, a microscopic protozoan. P. caudatum is the larger of the two species.
Considering that P. caudatum is 50% larger in size than P. aurelia, develop a hypothesis to explain why interspecific competition has an effect on the relative population size of P. caudatum.

10. Intra-specific Competition
These tadpoles are confined to a limited environment. What are they all competing for in that environment?
Propose an explanation for why the population size affects the number of weeks before metamorphosis of the tadpoles occurs.
What is different about this compared to the competition seen in graph B on the previous slide?

11. Ecological Succession
The observed process of change in the species structure of an ecological community over time.

12. Primary Succession
1. On what type of land does primary succession first begin to occur?
2. Why would most plants such as shrubs and trees find it difficult to grow here?
3. Suggest the mechanisms by which the first colonizers arrived on the land.
On what type of land does primary succession first begin to occur?
Why would most plants such as shrubs and trees find it difficult to grow here?
Suggest the mechanisms by which the first colonizers arrived on the land.

13. The first colonizers are referred to as the pioneer community
The first colonizers are referred to as the pioneer community. These can include lichens, mosses, ferns, and bacteria—all organisms with low nutrient requirements.
As they colonize, they break the weathered rock surface, which helps to create the first thin layer of soil.
Without soil other plant life cannot be sustained and without plants no animal life can exist.

14. Notice the colonizers in diagrams C and D are taller and require more nutrients than those in the pioneer community.
Considering what you already know about plants and photosynthesis, why might it be a competitive advantage for a plant to be taller?
2. What happens to the pioneer organisms once the new colonizers become established?

15. As soil quality and quantity improves, the life forms present in the area undergo a series of changes, each referred to as a seral stage. Eventually a stable climax community is formed.
Most climax communities are mature forests. What features of mature forest species, such as oak trees, make them able to dominate and compete in the ecosystem?
What environmental factors may affect the type of climax community that develops in an ecosystem?

16. As the newer colonizers begin to take over, animals will also begin to appear so they can feed on the more diverse food source. The pioneer plants die and decompose and the animals leave behind manure. Both add to the thin soil layer.
1. What effect will the addition of animal waste and decayed plant matter have on the soil and land?
2. How will grazing animals help plants to become established?
3. How will the grazing animals prevent or control further colonization by other plants?

17. Develop a definition for the term
primary succession, as it relates to the colonizing of barren land.

18. Secondary Succession

19. Secondary Succession
What stage of development does diagram A represent?
What appears to have happened in diagram B?
What process will begin again after this event has occurred?

20. What effect does an existing soil presence have on the seral stages of secondary succession and the time it takes to return to the climax community compared to primary succession?

21. What is the MAIN difference between Primary and Secondary succession?
Consider each event below and determine if the recovery process for the environment will happen by primary succession or secondary succession.
Melting, receding glaciers.
b Logging a wooded area.
c. Major flooding of a creek bed.
d. Volcanic eruption with lava flow.