Artificial selection

Artificial Selection: 

Definition:
 "It is the process in which organisms with the best or desired traits/characters are selected and breed with one another, so that the traits/characters would be passed on the offspring.

" Artificial Selection of Darwin: 

One of the Darwin's most difficult task was to convince biologists that selection can produce changes within a species. He supported his argument by pointing out, that farmers and breeders have developed many varieties of animals and plants through artificial selection. 
 In addition, Darwin bred pigeons and got variety in colour, size, form and behaviour through artificial selection which gave him a clue to the concept of artificial selection but he was unable to appreciate how this could operate in nature. 

Pegion

Darwin used this observation to argue that species can change and its characters are not fixed. He said, if a change is possible artificially, a similar process of change of selection can also occur in nature. 

Applications of Artificial selection 

Now a days biologists have produced completely new varieties of animals and plants by artificial selection. Artificial Selection in Animals: Numerous varieties of animals e.g. sheep, goats, etc. have been produced by artificial selection to increase production of meat, milk, wool, etc. 

Analogous Organs: 

The organs that are similar in function but different in structure are called analogous organs. 
Convergent Evolution: 
The evolutionary process producing analogous organs is called convergent evolution. 

Vestigial Organs: 

The parts of body that were presumably functional at an early time in the ancestral form but have since become non functional. The presence of vestigial organs is an evidence in favour of evoiution because it would be much harder to account for non functional vestiges without being inherited from some ancestor where these were functional. 

Artificial Selection of Plants: 

 Many plant varieties, for example, fruits and vegetables are produced for better quality in production and taste by artificial selection. 

Evidences of Evolution: 

There are number of evidences which support the Theory of Evolution. These evidences are based on data obtained from many sources and in all cases interpretation shows that how evolution occur. Evidence for evolution comes from many fields as for example geology, biogeography, comparative anatomy, embryology, artificial selection and molecular biology. 
However, we shall discuss only the evidence from comparative anatomy and artificial selection. 

 Comparative Anatomy As Evidence Supported for Evolution

Evidence from cpmparative anatomy consists of two major types. Similar bones One is the underlying similarity of comparable structures in different species. Arm of a man, the flipper of a whale, the wings of bird and the forelimb of a bat, all contain similar bones and muscles but all have different functions.
 Their structural resemblance indicates that they were modifications over a time of some common ancestral structure. The term homology is applied to this phenomena in which organs are structurally alike but functionally different. 

 Homologous Organs: 

The organs that are same in structure but different in functions are called homologous organs. Divergent Evolution: The evolutionary processproducing homologous' organs is called divergent evolution. Examples: The non-functional bones in snake and whales are thought to be homologous with hipbones and nindlimbs of vertebrates. Basic pattern of Human grasping fore-limb bones.Bat (flying) Describe comparative anatomy supportectfor theory of evolution.