Lecture 17 Flashcards
Tolerance Range
Range of variation in abiotic factors within which a species can grow, live, and reproduce
What factors determine where a species is found?
1) Abiotic: Chemical and physical factors
- Nutrients, temperature, pH, sunlight
2) Biotic: Living Factors
- Species interactions
- All the organisms that are part of an individual’s environment
3) Dispersal
- Has the species ever been there?
Competition
Two or more individual organisms attempting to use the same scarce resource (-/-)
Intraspecific Competition
Competition between individuals of the same species
Interspecific Competition
Competition between individuals of different species
-Occurs when the niches of two species overlap
Ecological Niche
The range of resources that the species is able to use or the range of conditions it can tolerate
Competitive exclusion principle
The inferior competitor will be competitively excluded locally
Fundamental Niche
The total theoretical range of environmental conditions that a species can tolerate
-If the fundamental niche of two populations overlap, they might compete in nature
Realized Niche
The portion of the fundamental niche that a species actually occupies, given limiting factors such as competition with other species
-Because of interspecific interactions, the realized niche of a species is often smaller than its fundamental niche
If niches of two species do not completely overlap:
Niche differentiation may occur
-Change in resource use caused by competition; also called resource partitioning
Chickadee’s example
- Both species forage in tress for insects and seeds
- When found together (sympatric), chestnut-backed tends to forage in higher branches than black-capped
Take Home Messages
- Competition between species can lead to various outcomes (competitive exclusion, resource partitioning)
- Resource partitioning allows two species that use the same resource to coexist
- Competitive interactions among competing species shape communities
