Competition/Predation Flashcards
what are the two definitions for interspecific competition
1) the simultaneous requirements by two or more species for a resource that occurs in limited supply
2) any use or defense of a resource by one species that reduces the availability of that resource to other species
what is a resource
any substance that leads to changes in individual or population growth if the substance is increased or decreased
was nitrogen determined to be a resource
for plants yes, major. For humans no
Liebig’s law of the minimum
growth is not dictated by the total resources available, but the scarcest resource (limiting factor)
What is the competition exclusion principle or ‘gauses’s law of competitive exclusion’
2 species with the same niche cannot coexist
Grain Beetle situation
- 2 degree difference in environment switches competitive ability of 2 beetle species
- habitat diversity
what did the ocean study discover
nitrogen-iron co-limitation
- need to add both things for organisms to grow
Evidence for interspecific competition in nature
- Habitat shifts in allopatry and sympatry
2) Character displacement
3) Habitat differences and resource partitioning
4) Allelopathy
Habitat shifts in allopatry and sympatry
- when species separated do one thing
- when put together, they will change their habitat to stay away from eachother
Character displacement (ecological and reproductive)
tendency for 2 species to diverge in form (beak) or behaviour when in sympatry.
-natural selection will favour one of the birds
habitat differences and resource partitioning (2)
- the ghost of competitions past
2. competition in the present
the ghost of competition’s past
character displacement often is due to the competition between species in the past
competition in the present
- invasive species
- frequently leads to the displacement of native species that occupy similar habitats
- e.g. starling was introduced. very aggressive, space competition
allelopathy
chemical competition in plants and animals
- the release of chemicals by one species in order to reduce growth/survivorship of another species
example of allelopathy
black walnut trees secrete jugalone which is highly toxic and kills/injures other plant species within a 20 m radius
- some species r resistant to jugalone
salvia
produces volatile terpenes. Barren zone around them. With cages seeds germinated even in the presence of terpenes; there is an animal activity sufficient enough to produce this bare zone
niche
how an organism makes its living
elton’s niche
the role of a species in a community
hutchinson’s niche
all biophysical conditions that characterize the life of a species