What are the key concepts in the evolution theory of Darwin ?
The essence of Darwinian theory about evolution is Natural selection.
$(i)$ Rapid multiplication : Microbes divide very fast. They multiply and become millions of individuals within hours.
$(ii)$ Limited food and space : $A$ colony of bacteria (say $A$) growing on a given medium has built in variations in terms of ability to utilize a feed component.
$(iii)$ Struggle for existence : $A$ change in the medium composition would bring out only thay part of the population (say $B$) which can survive under the new conditions.
$(iv)$ Variations: In due course of time this variant population outgrows the others and appears as new species.
$(v)$ Survival of the fittest : Here we can say fitness of $B$ is better than $A$ under new conditions.
$(vi)$ Natural selection : Nature selects for fitness. Fitness is based on characteristics which are inherited.
(vii) Speciation : Adaptive ability is inherited. It has genetic basis. Species get selected and evolved. Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution.
Write short note on Lamarckism.
Theory of natural selection was given by
Contribution of scientist :
$(a)$ Charles Darwin
$(b)$ Lamarck
Origin of different types of beaks occur due to
$I.$ Use and disuse of organs
$II.$ Inheritance of acquired characters
$III.$ Branching descent
$IV.$ Natural selection
$V.$ Mutation
$VI.$ Reproductive isolation
The two key concepts of Darwinism from the given options are