2. Variation In Population Size Flashcards
Define population
Is all organisms of one species in a habitat.
Populations of different species in habitat make up a community
What is population size?
Total number of organisms of one species in a habitat.
This number changes over time becuase of The effect of various factors .
What is carrying capacity ?
Maximum stable population size of a species than an ecosystem can support
Varies as a result of both abiotic and biotic factors
Abiotic factors
Amount of light
Water
Space availability
Temp
When these conditions are ideal for species organisms can grow more quickly and reproduce successfully
Example
Temp of mammals surrounds is ideal
The metabolic reactions taking place means not much energy is used to maintain body temp
More energy used for growth / get food and reproduction so pop size increases
What happens when abiotic conditions aren’t ideal
Organisms can’t grow as fast or reproduce successfully
Biotic factors
Interspecific competition
Instraspecific competition
Predation
What is interspecific completion
Is when organisms of different species compete with eachother for same resources.
So resources could be reduced ie same food source so limited to fewer food
Meaning less energy for growth and reprodtuon so population sizes will be lower for both species
If one species is better adapted dying interspecific competition ?
Than the less adapted speech is likely to be our competed can’t wxita alone side better adapted species
Red and grey squirrels
Compete for same food and habitats - less available for food them both.
So where both red and grey squirrels live there’s small populated of both than if there was just one species
Red disappearing as grey squirrel has better chance of survival as larger so more fat for winter and can eat more types of food
What is intraspecific competition ?
When organisms of the same species compete for with each other for same repaid was
Cyclical change in pop size around ecosystems carry capacity - pop sinks / grows / sinks …
As pop increases when resources are plentiful but this causes pop to increase so more organisms competing for same amount of food/ space so become limited eventually. So this means smaller pop so less competition for space and food so more growth and reproduction - cyclical
What is predation ?
Where an organism kills and eats other organisms they prey on
Pop size of predator and prey are inter linked as the pop of one changes it chases the other pop to change too
As prey population increases…
More
Food for predators So predator pop grows
As pred pop grows more prey is eaten so prey pop deceases
Eventually less food for predators so pop decreases - so on so on
