Bio geographical evidence of evolution, Biology

Assignment Help:

BIO GEOGRAPHICAL EVIDENCE-

  • The patterns of distribution of animals and plants in different parts of the globe are termed as biogeography.
  • It is believed that around carboniferous period or slightly earlier all the present day continents formed a single large, irregular land mass called Pangaea.
  • Pangaea splited up and the smaller masses (continents) lighter than the underlying earth crust material gradually floated over it to their present position.
  • As the continents drifted away, the sea separated them, forming barriers to free intercontinental movements of organisms. Due to different environmental continents, organisms evolved independently in them.
  • Earlier whole land mass of Globe was one piece called Panagea. 200 - 300 million years ago it got divided as follows -

538_bio geographical evidence.png

  • Sclater (1858) first divided globe in six zoogeographical regions on the basis of avian fauna.
  • A.R.Wallace (1876) divided more scientifically on the basis of entire flora and fauna as:

(i) Oriental region

-

Asia (lower China, West Asia, Malaysia, Indonesia, India, Ceylon)

(ii) Australian region

-

Australia, New Zealand, New Guinea, Tasmania, Hawaiian Island.

(iii) Ethiopian region

-

Africa continent, Madagascar, Egypt, Sahara

(iv) Palaearctic region

-

Europe, Most part of China, Japan, USSR, Siberia, N. Sahara

(v) Nearctic region

-

North America continent (USA, Canada, Alaska, Greenland)

(v) Neotropical region

-

South America continent (Mexico, Galapagos island)

  • Wallace's Line divides Oriental and Australian region.
  • Darwin (1831) during his expedition on H.M.S. Beagle visited Galapagos Islands (900 Km off West coast of South America) and found many endemic (restricted) species.
  • He studied 13 different subspecies of finches (Darwin's finches by David Lack 1947) with different eating habits (originally seed-eating).
  • He reasoned it as suitable adaptation brought by environmental conditions and called the islands as " living laboratory of evolution "
  • Discontinuous (Allopatric) distribution: When closely related genera are found in different regions.
  • This indicated that after arising from common stock they were geographically separated and evolved differently.
  • Due to the geographical barrier they remained isolated and evolved as genera, examples - 2101_bio geographical evidence1.png
  • Continuous (Sympatric) distribution: When closely related genera are found in the same or connected region. e.g. Prototheria and Metatheria are found only in Australian region.
  • Sometimes referred as restricted distribution. endemic fauna.

Related Discussions:- Bio geographical evidence of evolution

What are the tissues that form the skin in vertebrates, Q. What are the tis...

Q. What are the tissues that form the skin in vertebrates? The skin of vertebrates is made of epidermis is an external layer of epithelial tissue and dermis a layer of connecti

The cell cycle, what happens to the liver cell during the cell cycle

what happens to the liver cell during the cell cycle

Pleuritis, P l e u r iti s It is the acute or chronic inflammatio...

P l e u r iti s It is the acute or chronic inflammation of the pleural membranes. It is characterized by pain during respiration, pleural effusion, and shallow rapid resp

Periphyton - aquatic ecosystem, Periphyton - Aquatic Ecosystem These a...

Periphyton - Aquatic Ecosystem These are organisms which remain attached or clinging to stems and leaves of rooted plants or substances emerging above the bottom mud. Usually

Explain the interaction of vitamin a with vitamin e, Explain the Interactio...

Explain the Interaction of Vitamin A with Vitamin E? Of the various nutrients, the interaction of vitamin E, proteins, zinc and iron with vitamin A is of significance. Know? Le

Interpretation of blood or serum nutrient value in pregnancy, Define Interp...

Define Interpretation of blood or serum nutrient values in pregnancy? Interpretation of blood/serum nutrient values in pregnancy is therefore complex compared to the non-pregn

Explain the nutritional and functional role of potassium, Minerals :- Potas...

Minerals :- Potassium Food Source      Fruits, vegetables, meats Nutritional Functional role Essential nutrient: Deficiency is rare. Salt substitute: KCl may be

Nature and distribution of viruses, Nature and Distribution of Viruses ...

Nature and Distribution of Viruses Although several infectious diseases of animals and plants had been found to be caused by viruses during early 20 th century, the true natur

Define clinical feature and medical complication for bulimia, Define Clinic...

Define Clinical Features and Medical Complications for bulimia? Unlike, anorexia nervosa, in bulimia you will find that symptoms are more difficult to detect because patients a

What do numeric pyramids represent, What do numeric pyramids represent? ...

What do numeric pyramids represent? Numeric pyramids show the number of individuals in each trophic level of a food chain.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd