Population rely on density
Density is the number of individuals per unit area or volume. Counting the number of organisms inhabiting
a certain area is often very difficult, if not impossible. Dispersion is the pattern of spacing of individuals within the area the
population inhabits.
A population is a group of individuals of a single species living in the same general area. Members of a population rely on the same resources, are influenced by similar environmental factors, and have a high likelihood of interaction with and breeding with one another.
Here are 5 properties of populations we should know.
- Size
- Density
- Dispersion
- Survivorship Curves
Density : Density is the number of individuals per unit area or volume. Counting the number of organisms inhabiting a certain area is often very difficult, if not impossible. For example, imagine trying to count the number of ants in 1 acre (0.5 ha) of land. Instead, scientists use sampling techniques to estimate the number of organisms living in one area. One sampling technique commonly used to estimate the size of a population is called mark and recapture. In this technique, organisms are captured, tagged, and then released.
Population ecology
Population dispersion is the observation of where individuals are found in a habitat. How individuals
“disperse” themselves. There are three main types of dispersion: clumped, uniform and random.
Dispersion : Dispersion is the pattern of spacing of individuals within the area the population inhabits. The most common pattern of dispersion is clumped. Fish travel this way in schools because there is safety in numbers. Some populations are spread in a uniform pattern. For example, certain plants may secrete toxins that keep away other plants that would compete for limited resources. Random spacing occurs in the absence of any special attractions or repulsions. Trees can be spaced randomly in a forest.
Survivorship Curves : A survivorship curve is a graph showing the number or proportion of individuals surviving at each age for a given species or group (e.g. males/females). Survivorship curves can be constructed for a given cohort (a group of individuals of roughly the same age) based on a life table. Survivorship or mortality curves show the size and composition of a population. There are three types of survivorship curves.