ADAPTATION FOR SURVIVAL

Adaptation is defined as the possession of special features or structure which improves the changes of an organism to survive in its environment. In other words, adaptation is the ability of an organism to live successfully in a particular habitat as a result of its structure, appearance and behaviour.

It is expected that every organism must adapt to its environment in order to survive. Organisms generally have features – structural (morphological) and behavioural features which enable them to live successfully in a given habitat. Such features which enable organisms to live well in a habitat are called adaptive features.

 

COMPETITION

Competition is defined as the interaction between members of the same population or species, occupying the same trophic level, to obtain mutually needed resources that are short in supply in their environment. In other words, it refers to the process by which living organisms in a habitat struggle or compete with one another for such limited essential needs in the environment, e.g. food, light, nutrients, mates, shelter and space.

 

Factors Responsible for Competition

The major factors or reasons for competitions is the need for organisms to share favourable conditions and scarce resources in their environment.

The reasons for competition among plants include:

1. inadequate light,
2. inadequate space,
3. inadequate nutrients,
4. insufficient water.

 

The reasons for competition among animals are:

1. inadequate food,
2. inadequate space.
3. inadequate mates.

 

Competition is much pronounced when environmental resources needed for the organism’s survival are very limited. During competition, few organisms which are well adapted control the scarce resources which enable them to grow and survive while the others neither grow nor survive, leading to their elimination.

 

Types of Competition

There are two main types of competition. These are intra-specific and inter-species competitions.

 

Intra-specific Competition

Intra-specific competition is also called intra-species competition. This is the type of competition between individuals of the same species or kind. In other words, when competition is between members of the same species, it is called intra-species competition.

Examples of intra -species competition are:

1. maize seedlings in a nursery,
2. a population of laboratory rats in a cage,
3. a flock of domestic fowls in a deep litter house.

 

Inter-specific Competition

Inter-specific competition is also called inter-species competition. This is the type of competition which exists between individuals of different species. Examples are:

1. Mango plants and grasses: The mango plants due to their large size and numerous branches and leaves are capable of eliminating the grasses by depriving them of nutrients, space and light.
2. Iroko tree and terminalia in a forest competing for light.
3. Competition between a herd of cattle and a herd of antelopes on a grazing land.

 

RELATIONSHIP BETWEEN COMPETITION AND SUCCESSION

In a succession, habitats which are newly formed are gradually colonized by different plant species step by step until a relatively stable community is established and later the habitat will be inhabited by animals. The change in a population caused by the replacement of the old members or the addition of the new ones as result a of competition is called succession.

As soon as a habitat is established, competition sets in. Be it intra-species competition or inter-species competition, members of the more successful species grow bigger and occupy more space or obtain more resources than members of the less-successful species. With time, the less-successful species become eliminated as a result of competition. In a habitat, plants and animals which make up the community undergo a series of changes with time. This process of change can be seen if an abandoned farmland is observed for several years. The species which first colonized the habitat would normally give way to other species. These species in turn give way to other species as result of competition. The process continues until a stable community is established.

Competition plays a part in determining the pattern in which species succeed one another in a habitat. The early inhabitants modify the habitat by their activities, and the later arrivals appear to be better able to compete and outgrow the previous inhabitants which gradually lose out, get reduced in number and finally become eliminated.