Evolution-3

Question 1

what observation was made by darwin on galapagos island

Answer 1

Of particular interest, small black birds
later called Darwin’s Finches amazed him. He realised that there were many varieties of finches in the same island. All the varieties, he conjectured,
evolved on the island itself. From the original seed-eating features, many
other forms with altered beaks arose, enabling them to become insectivorous
and vegetarian finches.

Question 2

what is adaptive radiation

Answer 2

This process of evolution of different
species in a given geographical area starting from a point and literally
radiating to other areas of geography (habitats) is called adaptive radiation

Question 3

australian marsupial radiation

Answer 3

Darwin’s finches represent one of the best examples of this phenomenon.
Another example is Australian marsupials. A number of marsupials, each
different from the other (Figure 6.6) evolved from an ancestral stock, but all
within the Australian island continent.

eg: kangaroo, koala, bandicoot, wombat, tiger cat

Question 4

give an example of convergent evolution and adaptive radiation

Answer 4

When more than one adaptive radiation
appeared to have occurred in an isolated geographical area (representingdifferent habitats), one can call this convergent
evolution.

Placental mammals in Australia also
exhibit adaptive radiation in evolving into
varieties of such placental mammals each of
which appears to be ‘similar’ to a corresponding
marsupial (e.g., Placental wolf and Tasmanian
wolf-marsupial)

mole and marsupial mole
anteater and numbat
lemur and spotted cuscus
flying squirrel and flying phalanger