What is Natural selection?
- The process through which populations of living organisms adapt and change is called
Natural selection.
- Whenever there is a slight glitch in the DNA replication process, it may lead to new varieties which are formed accidentally. Thus, all biochemical reactions are not accurate and these variations create new varieties of individuals in an already existing
For example,
When frogs reproduce, there are times when a frog with an unusual body, say yellow skin, is born. As time passes by, the yellow frog too finds favourable conditions for breeding more yellow frogs. In due course of time, there are equal numbers of both yellow and green frogs. Suppose one day, the place where these frogs reside is invaded by eagles and they eat up most of the yellow frogs as they are quite visible among the green foliage. During autumn, the reverse takes place and it is the turn of the green frogs to be eaten up as the camouflage won’t work during autumn. Depending on the ones being preyed upon, the frog population of either the green or the yellow frogs is on the increase. This is the survival mechanism of the frogs. This process is called Natural selection.
What is Accidental survival?
- The survival of some individual of the population under unfavourable conditions, in which all other individuals died, merely by chance or by luck if called Accidental
For example,
Consider a situation in which the green frogs live in a pond while the yellow frogs have their separate pond. Some pollutant has been released in the pond of the yellow frog. The population of the yellow frogs came down in no time even in autumn. The green frogs
now became a majority. Thus, the offspring of the green frogs would increase in number as compared to the yellow frogs. This is called Accidental survival.
What are Inherited traits and Acquired traits?
- Inherited traits – Traits which affect the genes, modify them, and are passed onto their offspring are called Inherited traits.
- Acquired traits – Traits which cannot be passed from one generation to the next, but affect only the physical body of an individual, are called Acquired traits.