Question

Read the following statement having two blanks A and B.

Branching descent is a concept given by _____A____ and it supports _____B____.

The correct option for the two blanks is:

Answer 1

Branching descent and natural selection are the two key concepts of the theory of natural selection which was proposed by Charles Darwin. According to him, organisms better suited for the environment with characters will be selected by nature and they will reproduce more offspring.

He believed in the origin of new species from a common ancestor due to natural selection. Like branches originating from a trunk in a tree, from a common ancestor many species will be formed. It is called branching descent.


The process of evolution of different species in a given geographical area starting from a point and radiating to other areas of geography (habitats) is called adaptive radiation. Adaptive radiation gives rise to a variety of species from an original ancestral stock. Branching descent also tells about the formation of new species from a common ancestor. So, branching descent supports adaptive radiation. One of the examples of adaptive radiation is of Australian marsupials. A number of marsupials like marsupial mole, sugar glider, koala, bandicoot, etc. are different from each other and have evolved from a common ancestral stock, but all within the Australian continent.

Convergent evolution is the evolution of similar features in different organisms because they live in similar environments. For example, a shark is a fish whereas a whale is a mammal. Both are of different origins, but have similar streamlined bodies for swimming.

Mutation theory is proposed by Hugo de Vries. Mutation is the sudden, random, heritable changes in DNA. According to him, new species originate as a result of large, sudden, heritable changes. But Darwin never believed in mutations.