NEET BIOLOGY

Detailed explanation-1: -1: Darwin’s Finches: Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources.

Detailed explanation-2: -Later, Darwin concluded that several birds from one species of finch had probably been blown by storm or otherwise separated to each of the islands from one island or from the mainland. The finches had to adapt to their new environments and food sources. They gradually evolved into different species.

Detailed explanation-3: -Darwin’s finches are a classical example of an adaptive radiation. Their common ancestor arrived on the Galapagos about two million years ago. During the time that has passed the Darwin’s finches have evolved into 15 recognized species differing in body size, beak shape, song and feeding behaviour.

Detailed explanation-4: -The avian palaeontologist David Steadman argued, based on morphological and behavioural similarities (1982), that the blue-back grassquit Volatinia jacarina, a small tropical bird common throughout much of Central and South America, was the most likely direct ancestor of the Galápagos finches.

Detailed explanation-5: -The most studied animals on the Galápagos are finches, a type of bird (Figure below). When Darwin first observed finches on the islands, he did not even realize they were all finches. But when he studied them further, he realized they were related to each other. Each island had its own distinct species of finch.