How are evolutionary relations between organisms traced? - Vidyadip

Question

How are evolutionary relations between organisms traced?

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Answer

Evolutionary relationships can be traced by following methods:

Fossils: Fossils are the preserved traces of the organisms which lived in the past. They are a connecting link between two classes. They provide evidence for evolution. Analysing the organ structure in fossils helps us to judge how far the evolutionary relationship goes. For example: Presence of feathers in some fossils of dinosaurs indicate the birds are closely related to reptiles.
Homologous and analogous organs: Homologous and analogous organs provide evidences for single ancestral linkage e.g. forelimbs of a man, a lizard, a frog, etc. seem to be built from the same basic design of bones, but they perform different functions. Similarly, the wings of an insect, and a bird, have different structures, but they perform the same function of flying. Analogous organs actually provide mechanism and evolution.
Embryological evidences: Development stages of embryos help to understand the common ancestry. For example, similarity in the embryos of vertebrates indicate that they have evolved from a common ancestor.

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