Morphological and anatomical evidences of evolution, Biology

Assignment Help:

MORPHOLOGICAL AND ANATOMICAL EVIDENCES -

(i) HOMOLOGOUS ORGANS -

  • The organs apparently similar or dissimilar in structure and function, but of similar embryonic origin. Term homology used by Richard Owen 1804 - 1892.
  • A detailed and extensive study showes that all of them have following characteristics.
  • A fundamental similar plan
  • Contain approximately the same 'number of bones

1056_homologous organs.png

  • e.g. Fore limbs of whale, birds, bat, horse & man.
  • Mouth parts of insect is mode up of Maxilla, mandible, Labium, Labrum and hypopharynx but are adopted for different mode of feeding.
  • When function are different then it is called divergent evolution.

(ii) ANALOGOUS ORGANS -

  • The organs that have the same function and have superficial resemblance to one another but are dissimilar structure details and origin.
  • The phenomena among widely different groups is called convergent evolution.
  • e.g. Wings in insects, birds and bats are dissimilar in structure but similar in function i.e. flying.

(iii) VESTIGIAL ORGANS -

  • The organs that are present in reduced form and are useless to the possessor but correspond to the functional organs of related past animals.
  • e.g. Appendix, muscles of pinnae, nictitating membrane, coccyx, canine teeth and third molar in man, the rudimentary pelvic girdle in python.
  • In human beings total 180 vestigial organs are known.

382_vestigial rgans.png

(iv) ATAVISM (Reversal) -

  • It is the reappearance of certain ancestral characters that had either disappeared or reduced.
  • Example. Power of moving pinna in some person, greatly developed canine teeth, exceptionally long dense hairs (Lionboy of Russia), short tail in some babies, presence of additional mammae in some individuals.

Related Discussions:- Morphological and anatomical evidences of evolution

Botany, subject for botany assignment

subject for botany assignment

What is eutrophication in ecology explain briefly, What is Eutrophication i...

What is Eutrophication in ecology explain briefly? Freshwater ecosystems demonstrate the close relationship between aquatic and terrestrial ecosystems. Until recently, most peo

Functions of gluconeogenesis, Functions of Gluconeogenesis The signifi...

Functions of Gluconeogenesis The significance of gluconeogenesis include: 1)  During starvation or during periods of  limited  carbohydrate intake, when  the levels of liv

What do you mean by polyester, Q. What do you mean by Polyester? Polyes...

Q. What do you mean by Polyester? Polyester (ES) or polyethylene terephthalate (PET): PET is a very strong transparent glossy film, which has good moisture and gas barrier p

Organs in animal - excretion, Normal 0 false false false ...

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

Enzymes, what is rennin? how does it work? and what is its optimum pH level...

what is rennin? how does it work? and what is its optimum pH level and activity temperature?

History of psychiatric nursing, History of Psychiatric Nursing: In 187...

History of Psychiatric Nursing: In 1873, Linda Richards, developed better nursing care in psychiatric hospitals, and organized nursing services and educational programmes  in

Determine the nature and degree of abnormality, Determine the Nature and De...

Determine the Nature and Degree of Abnormality The nature and degree of abnormality will effect normal neural growth and maturational outcome. For example, in an adult damage t

How is genetic engineering used to create bacteria, How is genetic engineer...

How is genetic engineering used to create bacteria capable of producing human insulin? In a production of human insulin by bacteria the human insulin gene is incorporated into

Physiology, Slacklining is the act of walking across a suspended nylon stra...

Slacklining is the act of walking across a suspended nylon strap tied between two vertical anchor points. List the senses used to maintain an upright position while slacklining an

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