Flashcards in F215:03:08 Competition Deck (18):
When does competition occur?
When resources are not present in adequate amounts to satisfy the needs of all the individuals who depend on them
What is the correlation between the intensity of competition with the rate of reproduction and mortality and why?
As intensity of competition increases, rate of reproduction decreases because fewer organisms have enough resources to reproduce
And Death rate increases, as fewer organisms have enough resources to survive
What are the two types of competition?
Who does intraspecific competition occur between?
individuals of the same species
What phase does intraspecific competition lead to and why?
Stationary phase, as it slows down the population growth as the individuals are competing against each other, and those most well adapted will survive
Explain how the stationary phase remains relatively stable
- If the population size drops, competition reduces as resources are more available, so the population then increases
- If the population increases, competition increases as there are less resources, so population reduces
Who does interspecific competition occur between?
individuals of different species
What can interspecific competition affect?
the population size and the distribution of species in an ecosystem
What did Gause conclude when he placed two species of Paramecium both separately and together
That the more overlap between the niches of two species, the more intense the competition
What is the competitive exclusion principle?
The idea that if two species have exactly the same niche then one will be out competed by the other and die out
What can the competitive exclusion principle be used to explain?
why particular species only grow in particular places
Explain why the competition exclusion principle is not always accurate?
As some observations and experiments have shown its not that simple:
e.g. Sometimes interspecific competition could simply result in one population being much smaller than the other, and the population sizes remain fairly constant
- Other variables may be included
What is allelopathy?
where plants can interfere with neighbouring plants' physiology by releasing chemicals into their habitat which inhibit growth, germination or nutrient uptake
Its a form of competition
Where are allelopathic chemicals released ?
From almost anywhere
Could be released for the roots directly into the soil, or they may leach out of leaves/fruit when the plant sheds them
Give two examples of allelopathy
- Black walnut trees release a chemical (juglone) that inhibits respiration in neighbouring plants. This allows the young walnut tree better access to light by preventing other plants from overcrowding
- Sorghum (a cereal plant) releases a chemical (sorgolene) through its roots which disrupts photosynthesis and respiration of neighbouring plants, giving it greater access to resources
Explain how a species' population size can be affected by intraspecific competition
-As limiting factors appear, individuals compete. Those well adapted will survive and reproduce, and those who aren't will die. It slows the population growth, so entering the stationary phase
- If the population size drops, competition reduces as resources are more available, so the population then increases but If the population increases, competition increases as there are less resources, so population reduces
Explain how a species' population size can be affected by interspecific competition
If individuals of 2 species compete each other, one species tends to out compete the other
Its population size stays high while the other species' decreases or it may even die out