Question

describe any three method of tracing evolutionary relationship among organisms

Answer 1

(1)EVIDENCES FROM PALAEONTOLOGY

1. Fossils : Fossil is an organic relic of a long dead life form.

Or

Fossils are the petrified remains and for impressions of the hard parts of the extinct organism preserved in the
sedimentary rock or other media.

Palaeontology : Study of fossils is known as palaeontology.

(2)HOW DO FOSSILS FORM LAYER BY LAYER

Let us start 100 million years ago. Some invertebrates on the seabed die, and are buried in the sand. More sand accumulates, and sandstone forms under pressure.

Millions of years later, dinosaurs living in the area die, and their bodies, too. are buried in mud. This mud is also compressed into rock, above the rock containing the earlier invertebrate fossils.

Again millions of years later, the bodies of horse-like creatures dying in the area are fossilised in rocks above these earlier rocks.
Much later. erosion by, sun, water flow, wears away some of the rock and exposes the horselike fossils. As
we dig deeper, we will find older and older fossils.

(3)MOLECULAR  PHYLOGENY

Ancestors of different organism including humans can be traced by studying the change in their DNA. 

A change in DNA means a change in its protein sequences. The ancestry or phylogeny determined by comparative study of DNA sequences is called molecular phylogeny.

Studies in molecular phylogeny help in the classification of organisms.