KEY CONCEPTEach population has a density, a dispersion, and a reproductive strategy. Population density - number of individuals that live in a defined area. Dispersion shows how individuals in a population are spaced.
Clumped dispersion Uniform Random There are three types of dispersion.
Clumped Individuals clustered together Occur when resources such as food or living space are clumped Or because of social behavior There are three types of dispersion.
Uniform (Even) Individuals are separated by a fairly consistent distance Result from social interactions resulting in individuals getting as far away from each other as possible Ex:establishing territories x There are three types of dispersion.
Random Individuals location is independent of the locations of other individuals Usually results from seed dispersal by the wind or by birds A survivorship curve is a diagram showing the number of surviving members over time from a measured set of births. Survivorship curves can be type I, II or III.
Type I low level of infant mortality and an older population common to large mammals and humans Type II survivorship rate is equal at all stages of life common to birds and reptiles Type III very high birth rate, very high infant mortality common to invertebrates and plants 14.4Population Growth Patterns
KEY CONCEPTPopulations grow in predictable patterns. The size of a population is always changing.
14.4Population Growth Patterns The size of a population is always changing. Four factors affect the size of a population. Immigration Emigration Births Deaths Population growth is based on available resources.
14.4Population Growth Patterns Population growth is based on available resources. Exponential growth is a rapid population increase due to an abundance of resources. 14.4Population Growth Patterns
Logistic growth is due to a population facing limited resources. 14.4Population Growth Patterns
Carrying capacity- maximum number of individuals in a population that the environment can support. A population crash is a dramatic decline in the size of a population over a short period of time. Ecological factors limit population growth.
14.4Population Growth Patterns Ecological factors limit population growth. A limiting factor is something that keeps the size of a population down. 14.4Population Growth Patterns
Density-dependent limiting factors are affected by the number of individuals in a given area. Predation Competition Resources (food) 14.4Population Growth Patterns
Density-independent limiting factors limit a populations growth regardless of the density. Unusual weather Natural disasters Human activities 14.5Ecological Succession
KEY CONCEPTEcological succession is a process of change in the species that make up a community. Succession regenerates or creates a community after a disturbance.
14.5Ecological Succession Succession regenerates or creates a community after a disturbance. 14.5Ecological Succession
There are two types of succession. primary succession started by pioneer species 14.5Ecological Succession
There are two types of succession. 2.secondary succession started by remaining species