Topic 19: Population in ecosystems Flashcards
What is an ecosystem?
An ecosystem is any group of living organisms and non-living things occurring together, and the interrelationship between them.
What is a community
All the populations of different species who live in the same place at the same time and can interact with each other.
What is a population
All of the organisms of one species who live in the same place at the same time and can breed together
What is a niche
The role that each species plays in an ecosystem
What do u call a specoes with a narrow niche
specialists
What do u call a species with a broad niche
Generalists
What kind of biodiversity do specialists have
High biodiversity
What kind of biodiversity do generalists have
Low biodiversity
Why are ecosystems dynamic (in terms of population)
- In most ecosystems population sizes rise and fall.
- This is due to the community of living organisms interacting with each other.
Explain how u get the distribution of the sigmoid growth curve
A population tends to increase until it reaches the maximum number of organism that can live in the habitat.
Explain the Lag phase on the sigmoid growth curve
Population growth begins slowly from a few individuals.
Explain the log phase on the sigmoid growth curve
Exponential growth occurs, the conditions are ideal and maximum growth rate is reached.
Explain the S- phase on the sigmoid growth curve
Growth rate begins to slow down as factors such as food, water and space become limiting.
Explain the stable phase on the sigmoid growth curve
Carrying capacity for the population has been reached and the population number becomes stable.
Explain the decline phase on the sigmoid growth curve
If there is a sudden change in the environment meaning that the environment can no longer support the population, such as a drought causing food shortage, the population will crash
What is carrying capacity
The carrying capacity is the population size that can be supported by a particular environment.
Where do you often see the decline phase
In artificial closed environments e.g growing bacteria on a petri dish
Name 5 limting factors of population size
- Fod
- Water
- Space
- Predaotrs
- Parasites (disease)
Why is the carrying capacity dynamic (give examples)
- new technology, increased food etc, can increase the carrying capacity
- limited food, drought, etc, will decrease the carrying capacity
What is the most important biotic factor controlling population
Competition
Name a few factors that organisms compete for
- food
- light
- territory
- reproductive partners
What is intraspecific competition
Intraspecific competition occurs between members of the same species.
What is interspecific competition
Interspecific competition only occurs when the niches of two species overlaps.
What happens when two species have similar / overlapping niches
They will outcompete each other
What is the competitive exclusion principle
When two species are competing for limited resources the one using the resources most effectively will eliminate the other. Thus two species cannot occupy the same niche indefinitely when the resources are limiting
Is population size often limited to one or several factors
Several factors
What will happen in an ecosystem where the prey population grows and why
to the predator population
- Prey population grows
- Predator population grows because more food is available
- This will eventually decrease the prey population due to the overwhelming number of predators
- The decrease in food supply will then decrease the predator population
