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

Find the equilibrium molality of solute species, Find the equilibrium molal...

Find the equilibrium molality of solute species? Consider a hypothetical system in which two aqueous solutions are separated by a semipermeable membrane. Solution α is prepared

Topic test, In what way do investigations build scientific knowledge?

In what way do investigations build scientific knowledge?

Define aids, Which one of the following statements is correct with respect ...

Which one of the following statements is correct with respect to AIDS? 1. The HIV can be transmitted through eating food together with an infected person 2. Drug addicts are

State the term - functional neuroanatomy, State the term - Functional neuro...

State the term - Functional neuroanatomy Functional neuroanatomy focuses on the study of anatomy using psychological measures. One application of this kind of research is to he

How do contraceptive pills generally work, How do contraceptive pills gener...

How do contraceptive pills generally work? Contraceptive pills generally have the hormones estrogen and progesterone. If taken daily from the 4th day after menses the abnormal

Define about the anthropometry method, Define about the Anthropometry Metho...

Define about the Anthropometry Method? Anthropometry refers to the measurement of the size and proportions of' the human body. Anthropometric prediction equations estimate body

Define mineral trioxide aggregate - root end filling, Define Mineral Trioxi...

Define Mineral Trioxide Aggregate - Materials for Root End Filling Widely used Favorable biocompatibility Superior sealing qualities when compared to S-EBA and am

What is the curvature of the lens, What is the curvature of the lens I...

What is the curvature of the lens In a human being and most other mammals, the first three mechanisms are not possible and accommodation occurs by the fourth mechanism only. T

Genetically modified foods-vaccines, Normal 0 false false f...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

How thirst and satiety influence water intake, How Thirst and satiety influ...

How Thirst and satiety influence water intake? Thirst and satiety influence water intake, apparently in response to changes sensed by the mouth, hypothalamus and nerves. When t

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