Population Biology Class Notes 6

I. Graphs of population growth Populations do not show linear growth, but exponential growth. 1. Exponential growth means that as a population gets larger, it grows faster. 2. This graph looks like a letter ‘j’.

B. The population cannot grow forever because of limiting factors Ex: food, water, space C. Eventually the ecosystem will reach its carrying capacity: NO MORE ROOM!

When the population falls below carrying capacity, the population will increase again, when it goes above the capacity, the population will decrease. This graph looks like an ‘S’

II. Patterns of population growth *Some organisms show patterns of slow growth, others show patterns of fast growth A. Rapid growth patterns are shown by organisms like insects who live in an unstable environment. They must reproduce before they die!

B. Slow growth patterns are shown by bigger organisms that live in a more stable environment, such as elephants or bears. They live in a climax community. There is plenty of time to reproduce.

Summary How is exponential growth different from linear growth? Why do populations that are growing exponentially stop? What factors are fast or slow growth patterns based upon?