Presentation 5 3
- 2. This diagram from Click4Biology summarizes definitions well. Immigration is movement of organisms into the population. Emigration is movement of organisms out of the population. Natality is birth of new organisms. Mortality is death of organisms. Decrease Increase
- 3. From Mader, page 849 From Click4Biology
- 4. From Miller, page 122 As resources become less available, the population growth slows or stops. The growth of this population has leveled off at its carrying capacity. The carrying capacity is the largest number of individuals that a given environment can support.
- 5. Exponential growth occurs when the individuals in a population reproduce at a constant rate. At first, the number of individuals in an exponentially growing population increases slowly. Over time , the population becomes larger and larger until it approaches an infinitely large size. As resources become less available, the growth of a population slows or stops. Population growth may slow down when the birth rate decrease, when the death rate increases, or when both events occur. Population growth may slow down when the rate of immigration decreases, the rate of emigration increases, or both.
- 6. Many different factors can limit population growth. These are called limiting factors . Competition (nutrition, space, etc.) Predation Parasitism and disease Drought and other climate extremes Human disturbances The first three of these are density-dependent factors.