Question

What is the indirect evidence of evolution? What are homologous and analogous structures? What is convergent evolution? How does similarity of proteins between different species support the idea of evolution?

Answer 1

Indirect Evidence for Evolution:

It can provide evidence only on the basis of inference about the fact in dispute.

Ex: Embryology, Vestigial Structures, Analogous Structures, Homologous Structures, Physiological Evidence, Biochemical evidence/ molecular biology.

According to the evolution fossils are only considered as direct evidence for evolution and remaining other evidences are indirect.

Indirect evidences for evolution:

1. Comparative anatomy evidences:

a. Presence of homologous organs.
b. Presence of vestigial organs.
2. Biogeography evidence: Presence of same type of organisms (Ex: fresh water lung fish) in widely separate continents.

3. Developmental biology evidence: Recapitulation of ancestral/evolutionary history during embryogenesis.

Homologous structures: It can explain the body parts similarity in origin and structure among various species. The homologous structures found between the species can clearly indicates that the species can share a common ancestor.

Ex: The skeletal structure of the limbs of a human, dolphin, cat, and bat are all alike, showing that they share a common ancestor

Analogous structures: It can explain the body parts similarity based on the same job evolution. It is not dependent from a common ancestor. Analogous structures can explain how species experience similar during the course of environmental pressures.

Ex: Bat wings and butterfly wings formed because they were both under similar environmental pressures

Convergent evolution: Convergent evolution is the independent evolution of traits which are evolved to serve the same function, but may share the same ancestors. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups. It explains the similar features in species of different lineages.

Proteins in all organisms are invariably composed of the same set of 20 amino acids. The amino acid sequences in 23 universally conserved proteins across the three major divisions of life (eukaryotes, bacteria and archaea) are same.

Ex: Hemoglobin carries oxygen in the blood. Myoglobin receives oxygen from hemoglobin and stores in many species.

So the proteins similarity between different species can support the idea of evolution.