Population

3 Important Characteristics of a Population

1. Geographic Distribution (Range)

- the area inhabited by a population

- example: whales occupy millions of square kilometers in the Pacific Ocean when migrating

2. Population Density

- the number of individuals per unit area

- Example: the population of saquaro cactus have a low density

3. Growth Rate

3 factors:

a. Number of births

- population can grow when its birthrate is greater than its death rate

b. Number of deaths

c. Number that enter or leave

- immigration – movement of individuals into an area

- emigration – movement of individuals out of an area

animals tend to do this in search of mates or food

If a population has abundant space and food, and is protected from predators and disease, then organisms will multiply.

Exponential growth – individuals in a population reproduce at a constant rate; under ideal conditions with unlimited resources, a population will grow exponentially

exponential growth # of bacteria is represented by a J curve

Time(hours)

Carrying capacity – the largest number of individuals that a given environment can support

Things that could limit population size would include: competition, predation, parasitism, disease, climate conditions, and human disturbances