What tracing evolutionary relationships mean
Evolutionary relationships can show common ancestry for populations and species using molecular evidence. This can be in the form of comparing proteins, nuclear DNA or even organelle genetic material
Tracing evolutionary relationships:
In order to find out the evolutionary relationships among organisms, we have to look for their common features. Different organisms would have common features if they are inherited from a common ancestor.
The study of body parts of animals of a particular group shows how apparently dissimilar animals have quite similar anatomical structures. For example, the forelimbs of man, cat, whale and bat are made up of the same skeletal elements. They have been modified to suit the environmental conditions in which these animals live.
A comparative study of the stages of the embryonic development of animals reveals that in their early stages they were very similar. These embryonic stages reflect their ancestry. The embryological stages of an organism give us an idea about the stages of its evolution.
Fossils are the remains or traces of organisms that lived in the past. Usually the hard parts of organisms (e.g., bones, shells and teeth) turn to stone like fossils. Sometimes fossils also include remains like skeletons, the preserved impressions of tracks left by organisms on rocks, and so on. Fossil records are a proof of the changes in and the relationships between various groups of organisms.