1. Community Ecology
Chapter 54

2. YOU MUST KNOW
The difference between a fundamental niche and a realized niche
The role of competitive exclusion in interspecific competition
The symbiotic relationships of parasitism, mutualism, and commensalism
The impact of keystone species on community structure
The difference between primary and secondary succession

3. B. Fundamental niche – potential niche
Niches
A. Ecological niche – total of biotic and abiotic resources that a species uses in its environment
B. Fundamental niche – potential niche
C. Realized niche – the portion of the fundamental niche the species actually occupies
Review inter- vs. intra-

4. II. Interspecific interactions
A. Can be positive (+), negative (-), or neutral (0)
Inter = between
Intra = within
Review inter- vs. intra-

5. B. Interspecific competition – for resources, -/-
1. Competitive exclusion– if two species compete for a niche, one wins, other goes extinct
Review inter- vs. intra-

6. Predation – predator & prey, +/- 1. Cryptic coloration – camouflage
2. Aposematic coloration – warning
Review inter- vs. intra-

7. 3. Batesian mimicry – harmless species evolves coloration to
3. Batesian mimicry – harmless species evolves coloration to mimic the coloration of a harmful or unpalatable species
4. Mullerian mimicry – two bad-tasting species resemble each other so predators avoid them equally
Review inter- vs. intra-

8. Herbivory – herbivores & plants, +/-
1. Selective advantage to animals that can recognize toxic plants
2. Selective advantage to plants that have protection like thorns, spines, and toxins
Review inter- vs. intra-

9. Symbiosis – species live in direct contact with each other
1. Parasitism - +/-
2. Mutualism - +/+
3. Commensalism - +/0
Plant roots and fungi

10. 1. Dominant species – species with the highest biomass
Community Structure
A. Species diversity – number of different species (species richness) and relative abundance of each
1. Dominant species – species with the highest biomass
Community with even species distribution is more diverse than one dominated by a couple species

11. Trophic structure – feeding relationships among organisms
1. Trophic levels – levels of organisms based on those relationship
Rule of 10 – only 10% of energy from one level is available to the next level

12. 2. Food chain – transfer of energy from one trophic level to the next

13. 3. Food web – two or more food chains linked together

14. C. Keystone species – species that can impact all of the others in a community
Pisaster –(starfish) keystone predator
Review inter- vs. intra-

15. Review inter- vs. intra-

16. D. Invasive Species - typically introduced to a new environment by humans, often lack predators or disease
Pythons
Review inter- vs. intra-
Zebra Mussels
Cane Toads

17. Foundation Species - cause physical changes in the environment that affect community structure
Beaver dams can transform landscapes on a very large scale
Review inter- vs. intra-
Kelp - provides shelter and suitable habitat for numerous other organisms

18. Succession – transition in species composition in an area over time
A. Disturbances - Storms, fires, flood, drought, human activity
1. May remove organisms or change resource availability
2. Intermediate disturbance hypothesis – moderate levels of disturbances may foster species diversity
Review inter- vs. intra-

19. 1. Ex. colonization of a newly formed volcanic island
Primary succession – living organisms gradually invade a region that was previously lifeless and without soil
1. Ex. colonization of a newly formed volcanic island
Review inter- vs. intra-

20. C. Secondary succession – an existing community is cleared by a disturbance that leaves the soil intact
Review inter- vs. intra-

21. Biogeography & Diversity
A. Latitude – more diversity in tropics than near poles
B. Land area – if all other factors are equal, the greater the area, the more diversity
Review inter- vs. intra-

22. C. Islands – include actual islands and areas like national forests surrounded by development
1. Size of island - larger the island the higher the immigration rates and lower extinction rates
2. Distance to mainland– farther away from mainland, lower immigration rates and higher extinction rates
Review inter- vs. intra-