1. Paleontological evidence such as fossils provide evidence of evolution over long periods of time as life forms change. 2. Comparative anatomy shows that organisms have homologous organs with the same structure but different functions, indicating common ancestry, as well as analogous organs with different structures but similar functions due to convergent evolution. 3. Biochemical evidence such as similarities in proteins and genes performing the same functions across diverse species also points to common ancestry through evolution.

1. Evidences for Evolution
1. Paleontological evidences
• Fossil are remains of hard parts of life-forms found in rocks.
2. Morphology and comparative anatomy
Homologous & Analogous organs
• Palaeontology Fossil

2. Homologous Organs
• Organs having the same structure
but different functions.
Humerus
Radius
Ulna
• Result of Divergent Evolution
• Indicates common ancestry

3. Analogous organs
• Organs having different structure
but have similar appearance and
perform similar functions.
• Result of Convergent Evolution
• Do not indicate common ancestry

4. • These are anatomically similar but
perform different functions.
• These are not anatomically not similar but
perform similar functions.
Homologous Organs Analogous organs
• They are result of divergent evolution. • They are result of convergent evolution.
• Indicates common ancestry • Doesn’t indicate common ancestry
• E.g.-
o Forelimbs of whale, bat, cheetah and
human
o Thorns of Bougainvillea and tendrils
of Cucurbita
• E.g.-
o Wings of butterfly and birds
o Sweet potato and potato

5. 3. Biochemical Evidence
• The similarities in proteins and genes performing a common given
function among diverse organisms give clues to common ancestry.
UUU
Phenylalanine
Bacteria Human

6. Adaptive Radiation
Common
Ancestor
Different species

7. 1. Darwin’s Finches
• Darwin travelled to Galapagos
islands and observed many varieties
of finches on the same island.
• All varieties had evolved from
original seed-eating finches.
• With alteration in beaks some
became insectivorous and some
herbivorous.
Common
Ancestor

8. 2. Marsupials of Australia
Marsupials Marsupial Pouch
Placental
mammals
• Placenta
• Mammary
glands

9. 3. Placental animals in Australia
When more than one adaptive radiation
appear to have occurred in an isolated
geographical area, and two or more
groups of unrelated animals come to
resemble each other for similar mode of
life or habitat, it is called convergent
evolution.