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

Respiration, how energy enters and then flows through a biologial system?

how energy enters and then flows through a biologial system?

Nutrition, list and explain the modes of nutrition

list and explain the modes of nutrition

Agro industrial-copper, Copper Copper is an essential trace element re...

Copper Copper is an essential trace element required for enzyme systems, iron metabolism, connective tissue metabolism, integrity of the central nervous and immune systems. Co

Lungs, LUNG S (PULMONES) - Present in pleural cavity. Covere...

LUNG S (PULMONES) - Present in pleural cavity. Covered by double layered pleura. Outer parietal pleura and inner visceral pleura. Both are continuous, slip on

Explain why methionine is the first amino acid, Explain why methionine is t...

Explain why methionine is the first amino acid in every growing polypeptide. The tRNA that pairs with the start codon on mRNA carries methionine. RNA having ribose; DNA contain

Why could a disease be more serious in a population, Why could a disease be...

Why could a disease be more serious in a population with a low genetic diversity? A population with a low genetic diversity could be more expected to be wiped out by a disease

What is the probability sum of the numbers will be 5, You roll two dice. Wh...

You roll two dice. What is the probability that the sum of the numbers on both dice will be 5?

Protozoan slides, Protozoans are a group of animal protists of more than 50...

Protozoans are a group of animal protists of more than 50,000 species and are found under almost all natural conditions where there is moisture. A protozoa11 is not as simple an or

Types of cell respiration, Q What are the kinds of cell respiration? Th...

Q What are the kinds of cell respiration? There are two types of cell respiration aerobic cell respiration a reaction with participation of molecular oxygen (O2) and anaerobic

Antinutritional factors, Antinutritional factors Unconventional feed resou...

Antinutritional factors Unconventional feed resources including many agriculture by-products are rich in  antinutrients and toxic constituents, and tannins being the most widely o

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