RELATIONSHIPS AND POPULATION DYNAMICS Flashcards
what are some of the different ways that populations can be characterised
- abundance
- distribution
- age structure
- rate of growth
what is abundance and how can it be expressed
abundance - also known as density - can be defined as the number of animals of a specific species per unit area
it can be expressed as:
- qualitatively: scarce, frequent, abundant
- quantitatively: 54 Tasmanian Devils living in an area of 80 square kilometres would have an abundance of 0.7 animals per km2
what is distribution
distribution is the spread of animals of a population over a given space. It can be clustered, linear, random ect
what is age structure and what can it be used for?
The age structure of a population identifies the number of its members that are:
at pre-reproductive age (too young to reproduce)
at reproductive age
at post-reproductive age (no longer able to reproduce)
The age structure of a population can be used to predict whether the population will increase in the future
define species richness
the number of different species in a given area
define limiting factors
are factors that stop the population from growing
eg)10 rabbits may live in a habitat that has enough water, cover and space to support 20 rabbits, but if there is only enough food for ten rabbits, the population will not grow any larger.
In this example, food would be the limiting factor
whats the carrying capacity
the maximum population size a habitat can sustain. It can be represented by the letter K
what are population dynamics and what are the different ones
Population dynamics is the study of changes in population size over time. Variables that influence population size include:
birth rate
death rate
migration rate - either into the population from other areas (immigration) or out of the population (emigration)
what’s the difference between density-dependent and density-independent factors
Density Dependent
Factors whose impact is related to population size
e.g. food supply, predation, disease.
Density Independent
Factors affecting population size which are not related to population size
e.g. bushfires, floods, salinity
what are the two types of growth and what are the different shapes
Exponential population growth: When resources are unlimited, populations exhibit exponential growth, resulting in a J-shaped curve.
In logistic growth, population expansion decreases as resources become scarce. It levels off when the carrying capacity of the environment is reached, resulting in an S-shaped curve.
