EVIDENCES OF EVOLUTION

Gokul Das N N

‘Buddha’ Mannuthy

Thrissur, Kerala

Email: nngdas@rediffmail.com

EVIDENCES FROM

Morphology & Comparative Anatomy Embryology Physiology & Biochemistry Palaeontology Biogeography Taxonomy Genetics & Molecular Biology

EVIDENCES FROM MORPHOLOGY & COMPARATIVE ANATOMY Homologous structures Vestigial Organs Analogous Structures Parallel Evolution Convergent Evolution Adaptive Radiation Atavism Connecting Links

Homologous structures

HOMOLOGOUS STRUCTURES

ALL VERTEBRATE BRAINS SHARE THE SAME BASIC THREE-PART STRUCTURE

DEVELOPMENT OF CONSTITUENT PARTS OF BRAIN VARIES ACROSS THE EVOLUTIONARY SCALE.

In fish, the cerebrum is dwarfed by the rest of the brain and serves mostly to process input from the senses. Cerebellum is well developed

In reptiles and amphibians, the cerebrum is proportionally larger

Birds have well-developed optic lobes, making the cerebrum even larger. Cerebellum is also well developed

Among mammals, the cerebrum dominates the brain. Cerebrum is most developed among primates, in

whom cognitive ability is the highest.

HEART IN VERTEBRATES

HYPOTHETICAL ANCESTRAL HEAT

HEART IN VERTEBRATES

HEART IN VERTEBRATES

CRUSTAEAN APPENDAGES

INSECT MOUTH PARTS

VESTIGIAL ORGANS

CONVERGENT EVOLUTION IN SHAPES

Ichthyosaurs, Dolphins and Sharks Living in the open ocean as a fish

eater requires a streamlined body and the ability to move very quickly when needed. These pressures caused first sharks, then ichthyosaurs and finally dolphins, to all adopt a very similar body shape and method of movement.

In all these animals the tail is the major motor, other flippers and fins are used merely for steering and the body has taken on a shape that has the least resistance to water.

CONVERGENT EVOLUTION

CONVERGENT EVOLUTION IN SYSTEMS FLIGHT

CONVERGENT EVOLUTION THYLACINES AND DINGOES

This is a favorite of most Australians. The Thylacine was a marsupial the same shape and size as the placental dingo. The Thylacine evolved in Australia from the same stock as quolls and native mice. It lived on the mainland as well as the island of Tasmania until the arrival of people. People brought with them dingoes, which are wild dogs.

The dingoes had the same lifestyle and diet as the Thylacines, but they had stronger jaws. Over a long time the dingoes out competed the Thylacines which wiped them out on the mainland.

ADAPTIVE RADIATION

DARWIN’S FINCHES

EVIDENCES FROM EMBRYOLOGY

Vertebrates that evolved from fish pass through similar embryonic stages. As a flexible notochord develops in the back, blocks of tissue called somites form along each side of it. These somites will become major structures, such as muscle, vertebrae, connective tissue, and, later, the larger glands of the body. Just above the notochord lies a hollow nerve cord..

Such similarities formed the basis for German biologist Ernst Haeckel’s biogenetic law, which states that an animal’s embryonic development recapitulates its evolution. Although scientists now know that this law does not hold absolutely, Haeckel’s idea has remained influential

AORTIC ARCHES

EVIDENCES FROM PHYSIOLOGY & BIOCHEMISTRY

Immunology Nucleic acid studies

Protein structure

GENETICS

Down’s Syndrome in Chimpanzees Bleeding Disorders in dogs & horses

Genetic Code is Universal !

ATAVISM

CONNECTING LINKS

NEPHRIDIA IN NEOPILINA ARE A SIGN FOR METAMEROUS ORGANISMS LIKE THE SEGMENTED WORMS (ANNELIDA), THAT IN EACH SEGMENT POSSESS THE SAME NUMBER OF EQUALLY BUILT

ORGANS.

LUNG FISHES

PALAEONTOLOGICAL EVIDENCES

EVOLUTION OF HORSE

EVIDENCES FOR HUMAN EVOLUTION

ARTIFICIAL SELECTION

EXAMPLES OF ADAPTATIONS

ANCESTRAL FOX ADAPTATION

SELECTION PRESSURE