Question

all of the following are required for natural selectional to give rise to evolution expect

a)traits must be variable

b)trait must affect fitness

c)trait must be heritable

Answer 1

Ans.

• Natural selection forms one of the fundamental aspect of theory of evolution along with genetic drift, mutation and migration.
• Sucessful occurance of natural selection to give rise to evolution depends upon fulfillment of following 4 cconditions ;

1). Reproduction -

• A population must create a new organization by reproduction in order for natural selection to show effect on a given population.
• Individuals having traits which are most suitable for their given environment reproduce more then those lacking such traits.
• The higher the rate of reproduction of a given population, the higher the competitive pressure an individual faces to survive.
• Such type of competition ensures the survival of most suitable members and extinction of weaker members.

2). Heredity -

• It works simultaneously with reproduction.
• Advantageous traits from parents must be transfered to their offsprings in order for natural selection to show it's effects.
• If such advantageous genes are not passed from parents to their offsprings then those traits may die with the parents without being passed on to the upcoming generations.

3). Variation in characteristics -

• Populations, where members have a variation in individual traits, are more liely to be affected by the natural selection.
• Nature can not select one trait over others without a variation in characteristics.

4). Variation in fitness -

• With regards to the evolution, the ability of an organism to survive and reproduce as much as possible is known as fitness.
• A prerequisite for natural selection to work over a population is varying level of fitness of individual members.
• This will ensure the survival of fittest traits.

• So, as mentioned above, conditions required for natural selection to give rise to evolution expect are -

1. Trait must be variable.
2. Trait must affect fitness.
3. Trait must be heritable.