All the organisms on this planet possess the capability of adapting to dissimilar and various environmental conditions. This happens because of the variation in the genes of the organisms. Due to this, their chances of survival increase. For instance, a polar bear has a body type and character traits that help in surviving in the extremely cold Antarctica. The dense fur coats on the body of a bear protect it from predators as well as the cold at the same time. Their body repels liquid and that keeps them warm in the cold.
An organism functions and survives as an individual entity and is made up of cells. The organisms can be classified through taxonomy into multiple groups like plants, fungi, etc.
Individuals of any species survive and live their life in a group in a geographical area that is well defined. Moreover, they share or fight for some resources that are similar for them and then they create a population.
A population has certain attributes that are absent in individual organisms. Such as an individual may die or take birth. Whereas, a population can have birth or death rates. The birth and death rates are said to be the per capita births or deaths. These rates might get reduced or increased depending upon the members of a population. There is one more attribute of the population that we call the sex ratio. Moreover, an individual can be counted as a male or female depending upon the gender, but a population can have a sex ratio at the same time. A population is composed of different ages of multiple individuals. In case the age distribution is planned for the population, it will result in a structure known as age pyramids. The structure of the pyramid defines the shape of the status of growth of the population, this can be the following:
Population size § or the population density (N) can be measured in numerical values but it may not be appropriate all the time.
The size of the population is not fixed. It keeps on showing variations with time, depending upon the availability of food, predation pressure, and reduces weather. The major and primary aspects that define the growth of the population are as follows:
If ‘N’ is the population density at a given time ‘T’, then its density at time T+1 will be = NT + 1 NT + [(B + I) – (D + E)]
Therefore, the density of the population will rise if the number of births + the number of immigrants i.e. (B + I) is greater than the number of deaths + the number of emigrants i.e. (D + E), else it will get reduced.
There are 2 main types of growth models and these are given below:
dN / dt = (b – d) × N
Let (b – d) = r, then
dN / dt = rN
Therefore, the ‘r’ in this equation will be called the “intrinsic rate of natural increase”.
For instance;
Here, ‘N’ = Population Density at a given time ‘t’
‘R’ = Intrinsic rate of natural increase
‘K’ = Carrying capacity
Since resources for the growth of the populations are limited. However, this model is considered a more genuine growth model.
All the plants, animals, as well as microbes under a biological community, communicate and cooperate with each other. These interactions are sometimes beneficial and sometimes neutral or detrimental to the species, individually or to both the species. The following types of interaction are possible:
The study of organisms and populations makes us understand that ecology is all about the relations among the living organisms and biotic as well as abiotic components of their environment. You can consider it with 4 levels of biological organisation, and these are: organisms, populations, biomes, and communities.
Profile
Settings
Refer your friends
Sign out
